Sulfur exchange and decomposition kinetics in solid Na 2S 2O 3

Abstract

An intramolecular sulfur exchange in solid Na 2S 2O 3 has been confirmed and improved exchange rate constants measured. The exchange occurs without detectable decomposition at a measurable rate from approx. 290°–350°C. The activation parameters are ΔH ≠ = 58·5 kcal mole −1 and ΔS ≠ = 17·7 cal mole −1 deg −1. At temperatures above 350°C, decomposition to sulfate and polysulfide occurs characterized by activation parameters ΔH ≠ = 74·5 kcal mole −1 and ΔS ≠ = 39·2 cal mole −1 deg −1. Mechanisms are suggested for the two processes.