摘要:

118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure.This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point.These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility.The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.

ISSN:0014-7672    

DOI:10.1039/TF92723FP001

出版商:RSC    

年代:1927

数据来源: RSC

摘要:

118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure.This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point.These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility.The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order.The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order.The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure.This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point.These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility.The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.

ISSN:0014-7672    

DOI:10.1039/TF9272300023

出版商:RSC    

年代:1927

数据来源: RSC

摘要:

118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure.This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point.These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility.The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order.The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order.The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure.This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point.These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility.The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13. THE ACTINIC ABSORPTION OF CHLORINE GAS, WITH RESPECT TO THE HYDROGEN CHLORINE REACTION. BY WILFKID TAYLOR, M.Sc., PEMBERTON FELLOW, UNIVERSITY OF DURHAM. Received, I st October, I 9 2 6. Communicated by Professor G. W. Todd. I. Introduction. I n dealing with the phenomena of photo-chemical reactions and mo- lecular activation by the action of light, a method of investigation which has attracted comparatively little attention is that of subjecting the illuminating radiation to various perturbing influences and observing the resulting change in the reaction initiated.Progress has been made chiefly in the study of the results of changing the frequency and the intensity. The latter has un- fortunately been the subject of much diversity of opinion and the former is bound up with it, inasmuch as experimental work has not yet been carried out with monochromatic light of which the frequency but not the intensity has been varied. I t should however be possible to pursue investigations in a different way by using an intense beam of white light and a filter in which the activated substance itself is the filtering medium.Although we are thus using the integrated effects from a whole wave-band, yet the composition of the emergent light may be varied in a known manner by altering the absorption spectrum ; an analysis of the results might possibly bring fresh evidence to bear upon the problem of molecular activation. The first experiment which suggests itself is to alter the composition of the light simply by increasing the effective thickness of the absorbing medium. For convenience we may employ the old terms “actinic power ” and “ actinic extinction ” for the sake of their descriptive values. I f now a beam of white light be passed through a filter tube containing chlorine gas at a given pressure and, then, allowed to fall upon a reaction vessel so as to induce the photo-chemical union of hydrogen and chlorine, the velocity of that reaction may be taken as a measure of the actinic power of the beam.i t is also a measure of the actinic absorption which has been carried out by the gas in the filter tube. By varying the pressure in the filter, and hence the concentration of the absorbing medium, and observing the correspond- ing changes in the reaction velocity, the actinic extinction curve is obtained. Bunsen and Roscoe gave this idea in 1857, but it would seem that an ex- tension of their work is greatly to be desired in view of the problems now confronting photo-chemistry. The determination of the actinic extinction coefficient has been attempted before, but the literature is again contradictory.Bunsen and 3132 THE ACTINIC ABSORPTION OF CHLORINE GAS Roscoe in their classical researches included the measurement of this quantity and found that when a coal gas flame was used as the illuminant, a column of chlorine 17-17 cm. long reduced the actinic power of the light to 10 per cent. They also varied the partial pressure of the chlorine by diluting it with air, but it must be noted that only four separate readings were taken in the latter case and two when the length of the filter tube was altered. in 1902 found that a depth of chlorine of 10 to 15 cms. completely removed the actinic power from the light. He said, ‘(When a bulb of hydrogen and chlorine gas is placed in a sufficiently large jar of moist chlorine gas and exposed to light, the bulb is perfectly screened from the actinic rays for an indefinite period.” Much, however, would depend upon the intensity of illumination employed.In strange contradiction to this, Mellor 2. Experimental Work. The rate of the combination of hydrogen and chlorine under the in- fluence of light may be determined by several methods, but the actinometer arrangement of Bunsen and Roscoe, subsequently used by Burgess and Chapman3 was considered to be the most suitable since it enables the whole course of the reaction to be followed. In principle, the actinometer consists of a bulb containing a mixture of hydrogen and chlorine together with a little water to absorb the HC1 formed by the reaction. This bulb is connected with a narrow bore index tube so that the contraction of the gas volume may be followed by the movement of an indicator.Side tubes with stop-cocks serve to admit and extract gas at will. In order to obtain the pattern which should combine the best proportions for size of bulb and diameter of index tube, eight different actinometers were constructed and compared in efficiency. It seemed to be of little advantage to increase the size of the bulb beyond certain limits ; the final readings were made with one of 7 cm. diameter and spherical form. The apparatus was repeatedly cleansed internally with a mixture of chromic and nitric acids and, finally, a little distilled water was introduced to lie at the bottom of the bulb. The gas mixture was prepared by electrolysis from pure concentrated hydrochloric acid.The chief drawback is the evolution of oxygen at the anode as the concentration of the acid falls; 4 to overcome this, some workers 5 have used large quantities of acid ; in the present experiments, a glass chamber holding 24 litres was employed. The electrodes together with two glass tubes passed through a stopper, sealed in and protected from the action of chlorine by ‘‘ pizein ” wax. Before commencing opera- tions, a stream of chlorine gas was passed through the whole system for several hours in order to sweep out all traces of air and to saturate all the liquids. The electrolysis was then commenced and the mixed gases were allowed to pass for several more hours, the bulb of the actinometer being strongly illuminated by an arc light meanwhile. The anti-catalysts were thus attacked by the activated chlorine and, in time, were removed from the system.The reaction system was immersed in a large thermostat-bath consist- ing of a tank of 2 0 gallons capacity fitted with a plate-glass port-hole in one Bunsen and Roscoe, Phil. Trans., 1857, 147,601. 2 Mellor, Y . C . S . , 1902, 81, 1280. s Burgess and Chapman, Y.C.S., 1906,8g, 1399. 4 Chapman and MacMahon, Y.C.S., 1gog,95, 135. Coehn and Jung, 2. physikal. Chem., 1924, 110, 720.W. TAYLOR 33 side through which light could be passed. The bulb was only a centimetre from the port-hole so that the light absorbed by the water was negligible. The illumination was provided by a “white” beam from a Pointolite lamp. After being rendered parallel by a lens, the light passed first through a shutter, then through the filter tube and, lastly, through the port- hole in the tank.The filter consisted of a glass tube of 5 cms. diameter, and 45 cm. length, fitted with two glass side-tubes for gas manipulation. The ends were closed with plane pieces of glass, sealed on with “pizein” and the whole was capable of holding a good vacuum. The filter tube was in connection with a pump, a gas supply tube and a manometer in which mercury covered with a long column of paraffin was used. In spite of the paraffin layer, the action of the chlorine on the mercury necessitated a re-cleaning operation every day, the deposits of mercury chlorides being removed with aqua regia. I t is notorious that previous quantitative work with an actinometer of this type has been productive of the most directly conflicting results, particularly in the investigation of a problem very analogous to the present one, namely the influence of light intensity on the reaction.’ Since it was possible, therefore, that some serious source of error might be inherent in the method, the experimental procedure was developed very carefully and a study was made of the degree of accuracy with which results could be repeated.For any one exposure to white light, a satisfactory curve could always be obtained on plotting the index reading with time. The Draper expansion was followed by a steady reaction velocity, the points lying very well on a straight line which could be prolonged for the whole length of the index tube (about 4 feet) without sensible deviation.When however the reaction velocity thus obtained was compared with another value obtained under precisely the same external conditions, it became evident that enormous variations were possible. The velocity was altered whenever fresh bubbles of gas were admitted to the actinometer, or when the reaction was inter- rupted, i.e. when the light was cut off and a dark period interposed between the two parts of an exposure. Over zoo exposures were made to examine this phenomenon, and it was found that the reactivity of the mixture was reduced by (I) admission of new gas, (2) an effect bequeathed from the preceding exposure, which developed during the following dark period. These results were in accordance with the theories of inhibiting agents advanced by previous workers, as may be shown briefly.The reaction velocity may be regarded as the product of three terms, the light intensity, the frequency of the radiation, and a quantity which we may call the ‘( sensitivity factor ” S, depending upon the quantity of anti-catalyst present. Any agency which will alter the concentration of anti-catalyst present will also modify the value of S. We are of course dealing here with an anti- catalyst belonging to the first class of inhibitors as distinguished by Norrish,2 since the reaction is merely diminished in velocity and not totally arrested. Now it is known that oxygen is an anti-catalyst of this type, and this affords an explanation of the observed results, since oxygen may be admitted in two ways : (I) with fresh gas from the generator, due to anodic liberation, and (2) during an exposure, when the light falling on the water in the bulb liberates oxygen as the result of a photo-chemical action between the water and the dissolved chlorine. I t may be added that the illuminated 1 Briers, Chapman and Walters, Y.C.S., 1‘926,129,562 ; also Baly and Barker, Y.C.S., zNorrish, Y.C.S., 1925,127, 2323.1921, 119,653. 334 THE ACTINIC ABSORPTION OF CHLORINE GAS chlorine has itself the power of removing the free oxygen by the Weigerts reacti0n.l These sources of error having been revealed, it was obvious that read- ings under different external conditions were only to be trusted when it was certain that the factor S was constant. Since this would have involved great experimental difficulties, a method wa5 devised whereby the effect of a variation in S was taken into account.I t was based on the observed fact that during the duration of any single uninterrupted exposure, the reaction velocity V and, hence, S also remained constant, presumably owing ‘to the fact that there was a short time lag in the photo-chemical evolution of oxygen from the water. A second source of white illumination, cc By” was provided and used as a standard. The procedure was then to commence an exposure with “ By” exchange for the illumination under examination by the operation 0 I 2 3 4 5 6 7 8 9 Time in Minutes. FIG. 1.-Types of reaction velocity curves obtained. of a switch and, finally, to exchange for “ B ” again. A curve with two dis- continuities was then obtained, the first and last portions of which were found to have the same gradient. The gradient of the middle portion was then calculated relatively to this common standard.This corrected reaction velocity was independent, within limits, of the sensitivity factor S and, in practice, only those values were used which entailed a correction of less than 10 per cent. Specimen curves are shown in Fig. I. In operating the filter tube, the procedure was as follows : An exposure having been given for white light, the filter tube was pumped out and the chlorine was permitted to flow through under pressure from a cylinder for a minute or two. The chlorine was then cut off and the pressure was reduced to a selected value at which it was left while an exposure was given to the Norrish and Rideal, Y.C.S., 1925, 127, 787.W.TAYLOR 35 actinometer. The pressure in the filter was read off on the manometer and tabulated along with the corresponding value of the reaction velocity calculated as described from the time-index curves. A complete series of readings was always taken without interruption and occupied about I 2 hours when all precautions were included. The gas pressures were not taken in ascending order, but were alternated at random. Several complete sets of readings were obtained, one of which is shown in Fig. 2, the values 0 20 40 60 80 Chlorine Pressures in cm. of Mercury. being tabulated below :- FIG. 2. TABLE I. ~ Temperature of Gas 18O C. Pressure of Chlorine in Filter Tube (in Cms. of Hg). 32.0 46 '4 62'4 17.4 53'4 28'0 36.4 12.4 Mean Value of Reaction Velocity with Standard Light.1.32 1-72 1.70 1-51 1-30 1-16 0.96 1-02 Tube 45 Cms. Long. Value of Reaction Velocity with Light through Filter. 4.60 2.r2 1-80 5'32 1-85 1-14 1-90 4-30 Relative Reaction Velocity. 3'56 1 23 1-06 3 '53 I '42 0'99 1.98 4-22 It had been anticipated that the final curve might be of the form of an exponential function, but it was found that the results yielded a curve which, though of somewhat similar shape, differed markedly from a true ex- ponential in that it did not tend asymptotically towards zero. In other words, while the greater part of the activating power of the light was36 THE ACTINIC ABSORPTION OF CHLORINE GAS cut down by a relatively small thickness of chlorine, there appeared to be a residual effect which further concentration of chlorine was able to reduce only slightly.In view of this result, it seemed desirable to obtain some additional confirmation. The possibility of stray light, or of light reflected from, or transmitted through, the tube sides was first investigated. When the light was stopped by placing a screen which just covered the aperture of the filter tube, it was noted that the reaction was completely arrested. Next, a very small aperture was used, so as to limit the beam to a fine pencil of rays along the axis of the tube and, so, to exclude any possibility of effects due to the side walls. The reaction values were thereby reduced greatly, but the ratios for different chlorine pressures were practically the same as before. An attempt was then made to measure the velocity of the reaction by an independent method and, for this purpose, the Draper expansion was con- sidered.This phenomenon, which is also known as the Pringsheim effect, 0 20 40 60 80 Pressures of Chlorine in Filter Tube (Cms. of Mercury). FIG. 3.-Draper expansions plotted against densities of filtering medium [chlorine gas]. is the sudden volume change which the mixed gases undergo at the instant of illumination. I t has often been dealt with in the literature of the subject and it is only necessary to say here that the magnitude of the ex- pansion is proportional to the subsequent steady reaction velocity. Hence a measurement of the Draper effect may be used in place of the latter to determine the rate of activation of the chlorine.To observe the effect, the same actinometer was used and the initial index movements were magnified by a small lens. Since they were often of the order of an inch, a fair degree of accuracy could be obtained. Much greater speed in reading could of course be obtained, but the method had the drawback that between each exposure, the value of S altered slightly. Three exposures were given with each filter charge and the mean was taken. The results are tabulated below and also plotted in Fig. 3. I t will be seen that there is a great similarity between the curves of Fig. 2 and of Fig. 3. Mellor and Anderson, Y.C.S., 1902, 81,414 ; also Norrish, Y.C.S., 1925, 127, 2323.W. TAYLOR 37 TABLE 11. Pressure of Chlorine in Filter Tube (Cms. of Hg). 59 50 39 30 24 19 =4 9 4 o (White Light) I5 9 '5 4 Mean Draper Effect in Inches.'074 -080 '09 1 -124 'I44 -180 '223 '290 '387 '505 -780 -22 (New charge given -31 to actinometer) '41 -60 Conclusion. The result of this work has been to establish the form of the actinic absorption curves obtained by varying the concentration of the absorbing medium. I t is not intended to give any theoretical discussion at present, since further work is in progress upon the " residual effect." Nevertheless, two points may be mentioned here. In the first place, the results seem to indicate a greater ease of trans- mission by the chlorine than has been supposed. So far from 10 cm. of chlorine removing the activating power, even 45 cm. were found to be ineffective, but this of course may be due to the more intense nature of the source employed. Secondly, the shape of the curve is such as to disfavour the idea that only a narrow range of frequencies is effective in promoting activation, since an exponential curve would then have been expected. I t would seem that in addition to those frequencies which chlorine gas is able to absorb readily, the activation may be produced by rays which pass through thicknesses of the order of jo cm. and, then, produce an effect of about 10 per cent. of the full reaction velocity under white light. In connection with this, we may compare the extinction coefficient obtained by Bunsen & Roscoe, namely 17-17, with this value of about 45. The difference is presumably due to the actinic power of the light from a tungsten arc being much richer than that of the coal gas flame employed by the above workers. Further, there seem to be peculiar phenomena con- nected with the influence of intensity upon absorption and Allmandl has quoted some unconfirmed figures from which it appears that a transmission factor may vary from 46 per cent. to 66 per cent. according to the nature of the light source. While closing this paper, the author would like to express his indebted- ness to Professor G. W. Todd for his kindness and help throughout the progress of the research. OpiicaZ Room, Physics Deparfmcn f, Armstrong CoZZege, NewcastZe-upon- Tyne. 1 Allmand, Trans. Faraday SOL., 1926, 21, 521.

ISSN:0014-7672    

DOI:10.1039/TF9272300031

出版商:RSC    

年代:1927

数据来源: RSC

摘要:

118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure.This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point.These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility.The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order.The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13. THE RESIDUAL EFFECT IN THE ACTINIC ABSORPTION OF CHLORINE. BY WILFRID TAYLOR, M.Sc., EARL GREY MEMORIAL FELLOW, AND ARTHUR ELLIOTT, BSc., ARMSTRONG COLLEGE, UNIVERSITY OF DURHAM.(Communicated 6y PROFESSOR G. W. TODD.) Received I 0th Decem Jer, I g 2 6. In the preceding paper (see p. 31) some experiments were described in which white light, after being passed through a filter-tube of chlorine gas, was used to promote the chemical combination of a mixture of hydrogen and chlorine. The results seemed to show that as the chlorine concentra- tion in the filter was increased, the actinic power of the emergent beam ceased to fall off rapidly and tended towards a limiting value which was not zero. I t was felt that this jnstified further work upon the action of the filtering media in removing the activating power from a beam of white light; the present paper deals with some experiments, which have been carried out in continuation of the previous work, having as their object the investigation of the reality of this ‘‘ residual effect.” The tube previously used, which was 45 cm.long, was never filled at pressures greater than atmospheric. Increased concentrations of chlorine could therefore be obtained either by using longer tubes, or by employing greater densities ; both of these methods were adopted. With regard to the latter, it was not convenient to use high gas pressures, but it was thought to be of some interest to obtain an equivalent result by the use of a liquid solvent in which the percentage of dissolved chlorine could be varied. There are, however, several points to take into consideration when using liquid solutions, the most important being the modification of the absorption spectrum.Although the absorption of the activating radiation is the property under investigation, it is obvious that this will depend on the optical absorption; the relationship between the two is in itself worthy of study, but in the present case, it was only desired to examine whether strong solutions of chlorine having very nearly the same absorption spectrum as the gas, give rise to the “residual effect.” The solvent may modify the optical propertieslof the dissolved molecules by submitting them to high molecular fields 1 and a normal spectrum similar to that of a gas is only obtained when the solvent molecules have very low values for their electrostatic moments.The ideal solvent would be hexane, with a zero moment, but it was considered preferable to use a liquid in which there could be no chemical action with the chlorine even under intense illumination. Carbon tetrachloride was therefore selected. In addition to being chemically neutral, its molecular moment is not too high, being as 4-8 to 10 compared with water at 15’ C. and, in addition, it permits of a rapid analysis being made to determine the strength of the solution. 1 Victor Henri, ‘‘ Structure des Molecules,” Chap. 11. 38W. TAYLOR AND A. ELLIOTT 39 Experimental Details. The light system and actinometer were exactly the same as described in the paper referred to above, the light from a “Pointolite” lamp being concentrated by a lens, and relative reaction velocities were obtained in the same manner as before.Instead of a filter tube of chlorine gas, a plane walled glass cell was employed, the light having to pass through a depth of 3 cm. of liquid. This cell was equipped with a closely fitting glass cap to prevent evaporation since the solution was very volatile. We were thus able to pass a strong beam of white light through a known quantity of dissolved chlorine and to measure the actinic power of the emergent light in terms of the velocity of the reaction between hydrogen and chlorine in the bulb of the actinometer. A saturated solution was made by passing a stream of chlorine from a cylinder through a tower of pure carbon tetrachloride. To obtain lower G .- Y 2 & -2 > 2 1’0 2.g 1’2 0 , + 0 , -8 -6 ‘ 4 ‘2 0 0 5 I0 15 20 25 x 1020 molecules per sq.cm. cross-section. FIG. I. [Filter Tube of Chlorine Gas.] concentrations, additional quantities of carbon tetrachloride were added to this stock solution. Unfortunately these solutions, especially those near the saturation point, were very unstable owing to evaporation and it was necessary to estimate the strength immediately after removing the cap of the filter cell at the end of an exposure. For this purpose 5 C.C. were transferred to a beaker and shaken with excess of aqueous solution of potassium iodide. The iodine liberated in the water layer was then titrated with N/IO sodium thiosulphate and the shaking continued until all the chlorine and iodine had passed from the carbon tetrachloride into the water.Another source of trouble lay in the tendency of some of the stronger solutions to become turbid, presumably owing to the internal liberation of chlorine. The turbidity could be removed by filtration and was always looked for carefully. In any case it may be observed that a cloudy liquid would decrease the intensity of the light transmitted and so would operate against the residual effect under investigation.40 RESIDUAL EFFECT IN ABSORPTION OF CHLORINE A whole range of solutions was taken in turn and the reaction induced in the actinometer was determined while each one occupied the cell. The results are set forth in Table I. In column (a) is given the estimated con- centration of the chlorine solution in terms of the amount of N / I O thio- sulphate required to titrate 5 C.C.of chlorine solution; in column (b) is given the number of chlorine molecules actually interposed per square centimeter of cross section of the beam; in column (c) is the corrected reaction velocity produced in the actinometer. TABLE 1. 0'0 78.0 43'1 45'1 40'3 33'4 29'3 24-8 22.7 19'3 15'3 14.1 13'3 7 '3 4 '3 1'5 (4. 3 66 0'39 0'54 0'33 0'39 0.5 I 0'48 0.60 0.68 0'72 0-92 0.86 1-06 1-62 2-38 2.96 Having now completed this series, the effect of large gas concentrations was studied by means of a very long filter tube. In order to carry the ex- periments as far as possible, a glass tube of 159.5 cm. was used, having a diameter of about 5 cm., although the effective diameter of the light beam was cut down by a series of apertures, so that only the axial rays were employed.The ends were closed by plane glass plates sealed on with "picein" wax. The arrangement of gas supply, pump and manometer were the same as in the experiments with the short tube and are described in the previous paper. The effect of the new tube was in fact simply to extend the curve given in this paper to regions of greater chlorine czn- centrations. The results of the experiments are given in Table II., and are illus- trated in Fig. I. CoIumn (a) gives the pressures of the chlorine in the filter tube as read by the manometer, while in (6) these are expressed in terms of the number of chlorine molecules lying in the path of unit area of cross section of the beam, the temperature and barometric pressures being allowed for, and in column (c) are the reaction velocities.I t may be remarked that the readings were not taken in the above order, but always in a random selection of the pressure. I t seemed very important to estimate the error due to the viscous drag of the liquid in the index tube. During the course of a reaction, the index liqdid moved so as to fill an additional length of about 40 cm. of milli- metre bore tubing. Trial runs showed that no deviations from a constant velocity could be detected over this range, so that if the viscosity played any appreciable part, it could only do so by causing a steady rise of pressure in the bulb to compensate for the additional viscous drag.W. TAYLOR AND A. ELLIOTT 41 TABLE 11. I '24 0.05 0'06 0.05 0.06 0.19 0.24 0.28 0'34 0.48 0'12 0'22 Taking the rate of reaction as the time rate of change of gas volume at constant pressure, it is found that the real reaction velocity is given by where u is the observed velocity of the index, V the volume of the bulb, a the radius of the tube andl the other symbols have their usual significance.Now since no reaction velocities had an index speed of more than I cm./sec., the numerical magnitude of B, on putting the values V = 16 C.C. approx. and a = 0.75 mm., is well below 0-001, and hence can be safely neglected. Conclusions. All the curves obtained so far, although exhibiting certain differences as yet unaccounted for, agree in showing a " residual " effect, that is to say, the activating power of the light after passing through large concentrations of chlorine, is greater than would be expected were the light monochromatic and absorbed in accordance with an exponential law. From an inspection of the curves, it appears that certain types of radia- tion present in ordinary white light, are only feebly absorbed by chlorine and, yet, are able to give rise to an appreciable amount of activation. I t is claimed that these results, while at present rather of a qualitative nature, indicate that, by the use of this method, some information may be obtained concerning the specific activating power of the feebly absorbed frequencies. Further work is at present in progress. The authors wish to regard their appreciation of the facilities and assist- ance afforded them by Professor G. W. Todd. Physics Department, Universiiy of Durham, Armstrong CoZZege, Newcastle- upon - Ty ne.

ISSN:0014-7672    

DOI:10.1039/TF9272300038

出版商:RSC    

年代:1927

数据来源: RSC

摘要:

118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure.This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point.These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility.The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order.The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order.The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure.This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point.These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility.The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order.The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order.The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.

ISSN:0014-7672    

DOI:10.1039/TF9272300042

出版商:RSC    

年代:1927

数据来源: RSC

摘要:

118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure.This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point.These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility.The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order.The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.

ISSN:0014-7672    

DOI:10.1039/TF9272300052

出版商:RSC    

年代:1927

数据来源: RSC

摘要:

118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.

ISSN:0014-7672    

DOI:10.1039/TF9272300056

出版商:RSC    

年代:1927

数据来源: RSC

摘要:

118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure.This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point.These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility.The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order.The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13. ON THE VELOCITY OF CHEMICAL REACTION I N T H E SILENT ELECTRIC DISCHARGE.BY G. A. ELLroTr, RAMSAY MEMORIAL FELLOW; S. S. JOSHI and R WINSTANLEY LUNT, 185 I EXHIBITION SENIOR STUDENT. Received 24th November, I 926, and read before the Society ozz 2 6th January, I 9 2 7. (Communicated by PROFESSOR F. G. DONNAN.) Despite the numerous investigations that have been made on chemical changes produced by an electric discharge through a gas, no satisfactory general hypothesis has yet been suggested to describe the mechanism of such changes. In this communication an hypothesis is advanced which leads to an expression relating the velocity of such chemical reactions to. the gaseous pressure and to the electrical factors which determine the discharge. The fundamental idea from which this expression is derived was suggested by Professor F.G. Donnan, F.R.S. It is that the velocity of such chemical reactions might be associated with the number of collisions between ions and gas molecules in which the energy of the ion is equal to, or exceeds, a certain critical value. This value can be regarded as the critical energy of activation associated with the particular reaction concerned. According to the collision theory of chemical reaction, the rate of chemical change in a gas is a function of the kinetic energy of the constituent particles; it is immatertal whether the kinetic energy is of thermal or electrical origin. The concept of critical activation energies may therefore be applied to chemical reactions in which the energy neces- sary to effect chemical change is of electrical origin. I t will be assumed, in order to simplify the discussion, that the radiations arising in the dis- charge produce no chemical changes. Under normal conditions the number of charged particles existing in a gas is known to be very srnalL1 When a gas is subjected to an electric field the energy acquired by the ions during their free paths increases with the field strength.When this energy is equal to, or greater than, a certain critical value, known as the ionisation potential when expressed in volts, new ions are produced by collision and the number of charged particles in the gas increases rapidly. Since the increase in the average kinetic energy of all the particles in the gas depends on the number of ions and on the field strength, no appreciable chemical change may be anticipated until ionisation by collision occurs. This deduction is in agreement with experimental observation.When ionisation by collision takes place the electrical conductivity of the gas increases markedly and the gas is usually seen to glow. 1 Harms., Phyysikal. Zeit., 1902, 4, I, 11. 57 558 CHEMICAL REACTION I N ELECTRIC DISCHARGE Consider I C.C. of gas, at a pressure 9, which is subjected to the discharge for a small time period, T. If N is the number of ion pairs per c.c., and v is their average velocity in the direction of the electric field, then 2NvT is the total ionic path traversed while the gas is subjected to the discharge. An ion which travels a distance x crns., in the direction of the field, E, acquires an energy Eex due to the field, where e is the ionic charge.If the critical activation energy for the reaction concerned is V,e, then x,, the corresponding critical ionic path, is equal to V,E - 1 crns. According to classical kinetic theory, which is assumed valid under the conditions obtaining in the discharge, c, the number of collisions of an ion per centimetre of its path which terminate free paths equal to or greater than x, is given by xc VO C = C . E - t = C . b - E E where C is the total number of collisions per centimetre of ion path, and I is the mean free path of the ion. Therefore the number of molecules of gas chemically changed, per C.C. in time, T, is VO 2NvT. Cc - iii and K, the velocity of reaction or the number of molecules changed per second, is given by v_o K = ~ N z , . C E - ~ E .- (1) Since C, the number of collisions per centimetre of ion path is pro- portional to the pressure, p , it may be expressed by c = kp where k is a constant. Substitution of this expression for C in equation (I) gives In order to apply this equation to experimental results, it is necessary to know the manner in which Nv varies with? and E. Equation (2) may then be used to calculate V,, the critical energy, from values obtained ex- perimentally for K, the initial velocity of reaction at various pressures and in a constant field, E. I t is necessary to identify K with the initial velocity .of reaction, since the nature of the gas will have changed after the com- mencement of the reaction and, therefore, Nv and Z will have different walues. I n many experiments on the chemical change produced in a gas by the action of an electric field sus aining ionisation by collision, it is found con- venient to enclose the gas in an insulating envelope of glass or silica, whereby the gas is separated from contact with the metal electrodes.By this means any possibility of the formation of metallic arcs, or of specific catalytic action by the metal electrodes, is obviated. A typical example of such a device is the familiar Semen’s Ozoniser in which the insulating envelope and the electrodes 41re concentric cylinders. It is now proposed to discuss briefly the application of equation (2) to experiments carried out in this type of discharge vessel. Such a discharge vessel can be considered as a system of three capacities in series, two associated with the dielectric walls and the thirdG.A. ELLIOTT, S. S. JOSHE AND R. W. LUNT 59 with the annular space containing the gas2 A current will flow through the ozoniser if an alternating potential, V, is applied to the electrodes and, if this potential exceeds a certain value, ionisation by collision will occur in the gas. The conductivity due to the ions in the gas may be represented by the inverse of a resistance term shunting the third condenser. From known values of V, of P, the power developed in the gas, of I, the total current and of the frequency of alternation, it is possible by vectorial analysis to evaluate V,, the r.m.s. potential across the gas space, and i, the r.m.s. value of the current carried by the ions2 If d, the width of the annular space, is small compared with the radii of the walls, then E, the field in the gas, is at any instant approximately uniform and its r.m.s.value is given by V,d - l. I t may be mentioned that the ratio VV, - is deter- mined by the dimensions of the ozoniser and by the nature of the gas. The current i per square centimetre carried by the gas can be ex- pressed in the form familiar in electrolysis, i = (U, + U-) Ne where U+ and U- are the velocities of the positive and negative ions re- spectively, in the field E, sustaining the current i. Therefore and i = 2vNe Nu = i/2e where v is the mean velocity of the ions. written ; Hence equation (2) may be I 1 Now I, the mean free path of the ions, ii equal to - =- and substi- C pk' tution in the above equation gives which may be written In this latter form the equation may most readily be tested by experi- ments carried out with a constant field, E.For then -O is constant and the expression on the right, in which all the quantities may be determined, should also be independent of pressure. In some experiments carried out in these laboratories it has been shown that the conduction current, i, measured for a constant value of the field on the gas, does not vary greatly over a limited range of pressures. For this case therefore we may write : KV E k K P where A = log - + log i, and is constant. Log -, and? should therefore a Warburg, Ann. Physik (rgog), 28, 1-17 ; Lunt, Phil. Mug. (1925)~ 49, 1238.60 THE ACTIVATION OF HYDROGEN be linearly related (E constant) ; this conclusion has been experimentally confirmed. It is interesting to consider an alternative expression in which the pro- duct Nv is expressed as a function of P, the power developed per C.C. in the gas, which is equal to the product of the field strength and the ionisation current per square i en ti metre.^ That is P = Ei; consequently, substitu- tion of this expression in equation (3) gives Equations (4) and (6) thus relate in a most general way the velocity of reaction and the critical activation potential to the gas pressure, the mean free path of ions producing activation and the electrical factors determining the discharge. In conclusion the authors desire to express their sincere thanks to Pro- fessor F. G. Donnan, F.R.S., for his active interest and valuable criticism during the development of this theory. The WiZliam Ramsay Laboratories of University College, London. Physical and Inorganic Chmisz'ry, 3An account of the procedure appropriate to the determination of the power de- veloped in the gas is shortly to be published by one of the authors (R. w. L.).

ISSN:0014-7672    

DOI:10.1039/TF9272300057

出版商:RSC    

年代:1927

数据来源: RSC

摘要:

118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure.This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point.These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility.The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order.The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order.The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure.This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point.These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility.The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order.The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order.The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No.13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure.This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility.The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions.Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order.The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.

ISSN:0014-7672    

DOI:10.1039/TF9272300060

出版商:RSC    

年代:1927

数据来源: RSC

摘要:

118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure.This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility. The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point.These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13.118 ELECTRICAL THEORY OF ADBORPTTON The writer considers the double layer as consisting of a swface of rigidly fixed atoms under continuous bombardment of positively and negatively charged ions, any particular point on the rigid surface becoming in turn negative, neutral and positive, these conditions arisdg in any order. The observed contact difference is the average effect of these conditions. Where several kinds of atoms are present in the solution the average number of any one of them at the surface will depend on their concentbration, valency and mobility.The variation of contact Werence from negative to neutral and positive was observed with cotton and aluminium sulphate near the neutral point. These variations occurred during the same experiment, the readings being direct measurements of E.1I.F.s developed by filtration under pressure. This point would be covered by putting n2 = 1 and = 2 or 3 in Mukherjee’s equation No. 13. G. A. ELLIOT?' 73 Dr. H. Borns inquired whether Mr. Elliott had also tried the arc method of Langmuir and experimented with Langmuir's flames of atomic hydrogen. Langmuir seemed to consider that the activation was essentially thermal and set in about 1300' C. Mr.W. Taylor asked whether the theory of activation by ionic impact would not have to face the same problems as had been encountered by the theory of activation by molecular collisions. For example, in applying the general equation (6), the quantity K was really thc: rate of formation of activated molecules, which could be considered as an intermediate product in any chemical action taking place. The observed rate of appearance of end-products would depend upon the nature of the subsequent proceed- ings in which the activated molecules were involved, and might well in- volve a further collision frequency, and therefore another power ofp. In addition, there was the loss of activated molecules due to reversion to the normal state. Professor Allmand asked Dr.Lunt whether any work had been done on more complex reactions in which the critical activation energy might be regarded as being shared between two molecules before collision. I n such 674 DISCUSSION a case, the fundamental equation x , = VoE-l would presumably not hold. With regard to Mr. Elliott’s paper, it was of interest that the life of the activated hydrogen appeared to be of the same order as that of Bornhoeffer’s atomic hydrogen. He suggested that the results of an investigation of the activation of chlorine in the electric discharge would be of considerable interest to the photochemist, as the temporary formation of C1, molecules was now being assumed by several workers in discussing the kinetics of the hydrogen-chlorine reaction. Dr.E. 0. Willey (contributed): I t is noticeable that both in Mr. Elliott’s work and also in the earlier experiments of Wendt and Landauer very small yields ofactive hydrogen have been obtained, these never exceeding 0.01 per cent. by volume when the corona or ozoniser is employed. During the course of some recent work by the writer and IDr. E. K. Rideal upon active nitrogen a few experiments were performed with active hydrogen pre- pared by means of the condensed discharge as used in the production of the nitrogen afterglow, and here hydrogen sulphide was obtained equivalent to 0.5 per cent. active hydrogen and at least 0-7 second after the hydrogen had left the discharge. A similar result was obtained when the extent of activation was measured by admitting nitrogen downstream from the dis- charge, ammonia being formed.I t is curious that when this stream of nitrogen was activated also no perceptible yield of NH, was obtained, all other conditions being the same and so it appears probable that the ammonia first formed was under these conditions of experiment decomposed by the active nitrogen present. The frequency of the discharge appears also to be of fundamental im- portance in the production of active nitrogen; the yield of this from a given discharge tube can often greatly be increased by the addition of a condenser of suitable capacity which is connected across the electrodes and appears to “tune” the circuit, so to speak. I t would be of much interest if Mr. Elliott could extend his restarches still further to a correlation of frequency, wave form and the production of active hydrogen, and the circumstances relative to its formation in the H.T.disruptive discharge. Professor Donnan, in reply to the remarks of Mr. Taylor, pointed out that the theory given in the paper was a first attempt to analyse the mechanism of chemical reactions in the ‘‘ silent ” discharge. I t was assumed that any molecule which received a critical energy increment by collision with an electron or ion of sufficient velocity became chemically active, I t was of course, quite possible that a proportion of these active molecules might afterwards become de-activated by collision or by radiation. In its present form, the theory of chemical activation by ionic or electronic collision was stated in the simplest terms, and would doubtless require ex- tension and elaboration.I t had already led to a relationship which agreed in form with that obtained by Mr. Elliott from his results on the activation of hydrogen. Mr. Elliott said that the active hydrogen obtained differed from the monatomic hydrogen of Langmuir, Wood and Bonhceffer in its behaviour in contact with glass wool and tungsten, and at the temperature of liquid air. I t thus resembled the ‘hyzone ’ studied qualitatively by Wendt and others, although Wendt worked with much smaller concentrations than those obtaining in the experiments just described, in which the greatest amounts of active hydrogen observed were of the order of I per cent. by weight. Probably in both cases the active hydrogen consisted of aggregates each comprising one hydrogen atom linked to one-or more hydrogen molecules ; recombination of the active hydrogen to form ordinary hydrogen might therefore be expected to be bimolecular and largely dependent on theC.C. TANNER 75 concentration of the active form. A study of the influence of both wave form and frequency on the production of chemical change in the silent electric discharge was certainly desirable, and they hoped to carry out experiments of this nature very soon. Dr. Lunt explained that the expression for the velocity constant of a reaction, in which chemical change is caused solely by collisions between reactant molecules and ions, was obtained on the assumption that every encounter in which the ion possesses energy equal to, or greater than, Voe, results in the formation of a chemically changed and stable molecule. No attempt had yet been made to derive an equation for more complex types of reaction. The fact that linear relationships, in the form of equation ( 5 ) , leading to definite values of V, had been obtained in the case of active hydrogen, and in the decomposition of nitrous oxide (to be published shortly by Mr. Joshi) was thought to warrant the presentation of the theory in this simple form. It would be interesting to know if Dr. Willey has measured the current and frequency in his condensed discharge experiments. I t is difficult to see in what way a condenser connected across the electrodes could be said to tune the circuit, for any such circuit has a characteristic natural frequency; without a knowledge of the circuit constants it is impossible to predict what influence the condenser would have on this frequency. Generally, it would have the effect of increasing the current across the electrodes, and this current is undoubtedly an important factor in the production of chemical change by an electric discharge.

ISSN:0014-7672    

DOI:10.1039/TF9272300073

出版商:RSC    

年代:1927

数据来源: RSC