Radiochemical Investigation of the Kinetics of the Electron Exchange Between the Oxidation States of Tin

The kinetics of the electron exchange between SnII and SnIV in 10.0 f HCl have been investigated by the use of a radio-active tracer. It is found that the rate of exchange is proportional to the product of the SnII and SnIV concentrations. In the HCl concentration range between 9.0 f and 11.0 f, the exchange rate is found to be proportional to the 0.3 power of the HCl activity, giving the empirical rate equation R = k [SnII] [SnIV] (HCl)0.3 Radio-active exchange experiments carried out at 0° C. and at 25.2°C. show this exchange to have an activation energy of 10.7 Kcal. per mole. The exchange is found to be homogeneous. It is found that exposure of the SnII-SnIV solutions to illumination from a capillary Hg arc gives a marked photochemical increase in the rate of electron exchange between the two valence states. Preliminary spectrophotometric investigations of cobalt-glycine systems also have been made.