Energetics of formation of I2– and (CNS)2– in aqueous solution

Abstract

The ΔH of formation of I₂^– and (CNS)₂^– in aqueous solution have been obtained from measurements of the equilibrium constants of the reactions I + I^–→ I₂^– and CNS + CNS^–→(CNS)₂^–. They are 5·6 and 6·4 kcal. (g. ion)^–1 respectively. From the former ΔH_f°(I₂^–)_aq and ΔG_f°(I₂^–)_aq have been calculated to be + 2·5 and + 1·0 kcal. respectively. The electron affinity of I₂ in solution and in the gas phase are estimated to be 4·6 and 2·4 ± 0·5 eV.