摘要:

Two new methods for measuring the rates of removal of mirrors in a Paneth apparatus have been developed. By measuring the rates of removal of lead and tellurium mirrors it was shown that the same number of radicals react with each atom of both metals. It is suggested that lead dimethyl and tellurium dimethyl are the compounds formed.

ISSN:0008-4042    

DOI:10.1139/v51-062

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

not available

ISSN:0008-4042    

DOI:10.1139/v51-063

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

Mixtures of methanol, ethanol, isopropanol,n-butanol, and isoamyl alcohol were resolved by partition chromatography on Celite–water columns, using carbon tetrachloride and chloroform as developing solvents, each alcohol being determined quantitatively by dichromate oxidation of the fractions thus obtained. Only 0.5 ml. of an aqueous solution containing 1–5 mgm. of each alcohol was required for an analysis. The method was used successfully in the analysis of a mixture of volatile fermentation products containingn-butanol, isopropanol, ethanol, acetoin, diacetyl, and acetone.

ISSN:0008-4042    

DOI:10.1139/v51-064

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

A simple, compact apparatus has been designed for the estimation of carbon in organic materials by a wet combustion procedure employing the Van Slyke–Folch oxidation liquid. Oxidation of the sample and absorption of the resultant carbon dioxide take place under reduced pressure. The carbon dioxide is transferred from the oxidation Mask by diffusion and is absorbed in stirred sodium hydroxide, the excess alkali being determined by titration with hydrochloric acid after addition of barium chloride. Samples containing from 0.3 mgm. to 15 mgm. of carbon may be analyzed with a probable error of 0.35%. Volatile compounds in aqueous solution may also be analyzed. Sulphur, nitrogen, and halogens do not interfere. Determinations were made on the following compounds; sucrose, succinic acid, cysteine hydrochloride, cholesterol, stearic acid, and acetone. An analysis requires from 20 to 25 min.

ISSN:0008-4042    

DOI:10.1139/v51-065

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

The solubility of ethyl ether in aqueous solutions of the nitrates of the alkali metals, the alkaline earths and magnesium, and ammonium, tetramethyl, tetraethyl, and tetra-n-propyl ammonium has been measured with high precision. The salting out at infinite dilution of salt, estimated by extrapolation from data for salt concentrations below 0.1 molal, conforms in a general way to the Debye theory, with some discrepancies. Data for high salt concentrations are also given.

ISSN:0008-4042    

DOI:10.1139/v51-066

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

The kinetics of the reaction of ethylene oxide in dilute aqueous solution at 25°C. with di- and tri-ethylamines, aniline, and pyridine have been investigated over a wide range of hydrogen and hydroxyl ion concentrations. The rates for all four amines were found to be very similar and were accurately expressed by the simple second order equation −doxide/dl = k(oxide)(amine). The results indicate that basic catalysis does not occur and that catalysis by hydrogen or ammonium-type ions, if it occurs at all, is of no significance in the pH range 4–14.

ISSN:0008-4042    

DOI:10.1139/v51-067

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

A kinetic study has been made of the reaction of ethylene oxide in pyridine solution in the presence of strong acids. The rate has been found to be dependent upon the concentration of acid and of oxide over a wide range of concentrations at 25°C. The specific rate constant, however, varies markedly with the nature of the acid anion and appears to decrease with increasing basic strength of the anion. The absence of large salt effects seems to indicate that the anion effect is of a physical rather than chemical nature and the results are therefore tentatively attributed to the nature of solutions of electrolytes in solvents of low dielectric constant.

ISSN:0008-4042    

DOI:10.1139/v51-068

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

In order to evaluate the rate constant for the reaction of atomic sodium with halides using the diffusion flame method, Hartel and Polanyi introduced three simplifying assumptions: that the mass flow of the carrier gas could be neglected, that there was a spherical distribution of sodium vapor in the reaction zone, and that the halide concentration was constant throughout the reaction zone. In an attempt to maintain the validity of the third assumption previous workers limited their experimental determinations to cases in which the collision yield was considerably less than unity. In the present contribution equations arc developed which remove this restriction and permit the evaluation of the rate constant without assuming a constant halide concentration. On carrying out the computation for a relatively slow reaction (Na + C2H5Cl) it was found that the error introduced by the third assumption was only of the order of 20%. The error for fast reactions would be considerably larger but can always be evaluated from the equations given. In some cases an approximate value of the error can be obtained without carrying out the complete computation.

ISSN:0008-4042    

DOI:10.1139/v51-069

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

Following the dehydration of certain hydrated salts in high vacuum, an evolution of energy occurs. X-ray studies have shown that this energy liberation is due to an amorphous to crystalline transition in the products of dehydration. Measurements have been made of the integral heats of solution of the dehydration products of copper sulphate pentahydrate and zinc sulphate hexahydrate formed at a series of low dehydration pressures. From these measurements, the fractional amounts of relatively high energy amorphous products formed at a series of low dehydration pressures have been calculated. It has been found that as the water vapor pressure near the reaction interface is increased, the fractional amount of high energy product decreases to a minimum, then increases, passes through a maximum, followed by a slow decrease. These results are interpreted in terms of a possible dehydration mechanism, and an estimation made of the effect of water vapor pressure on the over-all reaction rate. In the course of this study, the integral heats of solution of the crystalline hydrates involved have been determined. The heats of transition of the amorphous to crystalline forms of copper and zinc sulphate monohydrates are reported.

ISSN:0008-4042    

DOI:10.1139/v51-070

出版商:NRC Research Press    

年代:1951

数据来源: NRC