Temperature dependence of the equilibrium constant for iodine hydrolysis at temperatures between 25 and 120 °C

Abstract

The equilibrium constant for iodine hydrolysis at elevated temperatures has been investigated using absorption spectroscopy and a simulation computer program. The temperature dependence of the aqueous I₂ maximum extinction coefficient for visible light (at 460 nm) was first evaluated in a preliminary experiment using saturated I₂ solution. The time dependence of I₂ concentrations in dilute solution has subsequently been measured using the temperature-dependent extinction coefficient. The results were analysed by the simulation program, in which 11 normally accepted reactions were considered, and the equilibrium constant, K, was estimated. It was concluded that the K value at temperatures ranging between 25 and 120 °C may be expressed by log K(T)= 13880/T– 0.2445T+ 308.4 log T– 749.1, where the units of K and T are mol² dm^–6 and K, respectively.