摘要:

The cross section of Ce142has been determined by the activation method and found to be 0.95 ± 0.05 barns relative to a value of σCo59 = 36.3 barns. Disintegration rates were determined by a 4π counter. The value obtained agrees with that of Katcoffetal. (1949) also obtained by the activation method but differs markedly from that of Pomerance (1952).

ISSN:0008-4042    

DOI:10.1139/v56-135

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

A study of the viscosity behavior of the graft copolymers described in Part I has been made with dilute solutions in benzene at 25 °C. Although the slope constants of the Huggins equation increase with the frequency of branching when measurements are made in a capillary viscometer under 'free fall' conditions, this is shown to be attributable to the dependence of viscosity on shear gradient. At a constant shear rate, the Hugginsk′ values approximate to those of linear polymers. It is suggested that the marked increase in viscosity observed with decreasing shear rate for the graft copolymers is due to molecular entanglement.

ISSN:0008-4042    

DOI:10.1139/v56-136

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

The Raman spectra of liquid (CH3)3CH and (CH3)3CD were obtained photo-electrically and intensities and depolarization ratios measured. The infrared spectra of the corresponding gases were obtained from 3 to 35 μ. A vibrational assignment consistent with depolarization ratios and band contours has been made for the molecules on the basis ofC3νsymmetry and their spectra correlated.

ISSN:0008-4042    

DOI:10.1139/v56-137

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

An apparatus is described to measure volumetrically the amount of gas adsorbed by a catalyst at constant pressure and at exposure times as short as 0.1 min. The volumes of oxygen adsorbed by a technical silver catalyst at pressures of 200, 400, and 700 mm. and in the temperature range of 180° to 300°C. have been measured. Surface area determinations of 0.33 to 0.38 sq. meter per gm. of catalyst by physical adsorption and chemisorption methods show that each silver atom of the surface is associated with approximately one oxygen adatom at a monolayer coverage. The initial rate of adsorption of oxygen is directly proportional to its pressure. Observed transitions in the oxygen adsorption rates indicate that more than one type of oxygen complex occurs on the catalyst surface. The Elovich equation provides the best approximation of the adsorption rate data but is of limited applicability in interpretation of the mechanism of adsorption. Values of 22–29 kcal./mole and 17–25 kcal./mole have been calculated for the apparent activation energy and isosteric heat of adsorption respectively.

ISSN:0008-4042    

DOI:10.1139/v56-138

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

Deuterium was dissociated on a hot tungsten filament and the atom concentration measured by isothermal calorimetry. The recombination coefficient of deuterium atoms on a glass surface, coated with metaphosphoric acid, was found to be 3.8 × 10−5, and similar to that found for hydrogen atoms. The reactions of H-atoms and D-atoms with ethylene were found to be very rapid. The effects on the yields of the products and on their isotopic composition of variations of reactant flow rate, atom concentration, pressure, and atom-detector position were studied. The major products were methanes, ethanes, and ethylenes, with minor amounts of propanes and butanes. The methanes were always highly deuterated while the ethanes were slightly deuterated. A mechanism is proposed to explain the observations based on a flow pattern in the reaction zone. The possibility of differences in the reaction rates of variously deuterated intermediates is also discussed.

ISSN:0008-4042    

DOI:10.1139/v56-139

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

The reactions of active nitrogen with methyl, ethyl, vinyl, propyl, and isopropyl chlorides yielded hydrogen cyanide and hydrogen chloride as the main products. Small amounts of cyanogen and a polymer were formed from all the halides, and all except methyl chloride also yielded small amounts of C2and C3hydrocarbons. The observed changes in amounts of products recovered with different reactant flow rates were characteristic of a fast reaction in which complete consumption of either reactant occurs when the other is present in excess. Mechanisms for the reactions are suggested on the basis that relatively long-lived complexes are formed in the initial attack of a nitrogen atom on the alkyl chloride.

ISSN:0008-4042    

DOI:10.1139/v56-140

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

The Raman spectra of liquid CH3CHO and CH3CDO were obtained photo-electrically and depolarization ratios measured. Infrared spectra of the vapors and solids were also obtained. A vibrational assignment is given and the spectra correlated. The vibrational spectra of the acetyl halides reported in the literature are also correlated.

ISSN:0008-4042    

DOI:10.1139/v56-141

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

A method has been developed for the preparation of mercaptans from alkyl and aralkyl chlorides. This consists of the condensation of sodium N,N-dimethyl-dithiocarbamate with halides followed by alkaline hydrolysis or hydrazinolysis of the resulting N,N-dimethyldithiocarbamates (IV). In the hydrazinolysis of IV, an insoluble solid by-product was formed which was identified as 3-hydrazino-4-amino-5-mercapto-4,1,2-triazole. Although this method was found to have wide scope a few failures were encountered. Nitro-derivatives of IV were sensitive to alkali or hydrazine and yielded only tars on attempted degradation. β-Phenoxyethyl N,N-dimethyldithiocarbamates (IX) were found to possess a labile alkyl–oxygen bond so that in the presence of alkali or hydrazine only the corresponding phenols were formed. The labile nature of the alkyl–oxygen bond ceased abruptly when the alkyl chain of IX was increased so that 3-p-chlorophenoxypropyl and 4-p-chlorophenoxybutyl mercaptans could be prepared in high yields.

ISSN:0008-4042    

DOI:10.1139/v56-142

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

The interpolation theory has been applied to data on the adsorption of nitrogen, oxygen, and argon on rutile at 77 °K. It has been demonstrated that the oxygen and argon data cannot be interpreted on the basis of the Langmuir model, modified by the introduction of surface heterogeneity effects. The interpolation theory verifies, however, that the distribution of adsorption energies among surface sites, obtained by inversion of the nitrogen isotherm, is physically significant, and that nitrogen is suitable for BET surface area calculations.

ISSN:0008-4042    

DOI:10.1139/v56-143

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

Empirical equations recently proposed for the entropies of ions in aqueous solution involve a linear dependence on the first power of the valencyzand, in some cases, an inverse dependence on the square of a modified radius. Such relationships have no fundamental validity since the entropies are related arbitrarily to a zero value for the proton. It is shown that the entropy changes for reactions of various ionic types indicate that the entropy must depend onz2, as proposed by Born on the basis of simple electrostatic theory. When the entropies of monatomic ions are related to the absolute scale, in which the proton has a value of −5.5 e.u., they are found to vary linearly withz2/ru, where ruis the univalent radius defined by Pauling. The slope is found to be close to that predicted by the Born equation, and the non-electrostatic part of the entropy is shown to correspond to the movement of the ion in a free volume of 0.73 eu. Å.

ISSN:0008-4042    

DOI:10.1139/v56-144

出版商:NRC Research Press    

年代:1956

数据来源: NRC