The Autoxidation of Stannous Chloride. II. A Survey of Certain Factors Affecting this Reaction.

Abstract

The autoxidation of stannous chloride has recently been investigated by Filson and Walton (l), who studied the effect of hydrochloric acid on the reaction velocity and showed a linear relation between the velocity and the hydrogen-ion concentration. This paper is a continuation of the above work and is a general survey of certain factors influencing the rate of reaction. APPARATUS AND PROCEDURETwenty-five cc. of an acid solution of stannous chloride were placed in a 150-cc. Pyrex flask of the type used by Filson and Walton. The flask was placed in a thermostated shaking apparatus and connected to a waterjacketed burette containing oxygen gas a t the temperature of the thermostat, 25°C. When the system had come to constant temperature, the shaking apparatus was started and readings were taken on the volume of oxygen absorbed. The speed of shaking was selected as about 1000, since Filson and Walton had shown that higher speeds have no effect on the reaction velocity. REAGENTS AND SOLUTIONSSeveral brands of stannous chloride were used and were found to give varying results. Baker's "purified" salt gave results which were only slightly changed by three recrystallizations under nitrogen from hydrochloric acid solution, consequently this preparation was used in the experimental work. Solutions made from stannous chloride which had been dehydrated by treatment with excess acetic anhydride and washed with anhydrous ether (2) gave results which agreed with those obtained from the recrystallized hydrated salt.The solutions, made in 2-liter batches and stored under nitrogen, contained approximately 32 grams of stannous chloride per liter, and were I

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