Bourdon Gauge Determination of Equilibrium in the ZnSe(s)-I₂(g) System

Bourdon gauge measurements of samples of I2(g) plus ZnSe(s) have been made in the temperature range 900° -1200°K and over a fourfold range in pressure. The pressure vs. temperature behavior of the system can be described satisfactorily by the equilibria, (formula omitted) The standard enthalpy and entropy of the first reaction between 900°1200°K were calculated using the second law with the result; ΔH° = 23.1 kcal, ΔS° = 21.1 e.u. The standard heat of formation, ΔH°298f2 and entropy, S°298, of ZnSe (s) were found to be 44.2 kcal and 15.4 e.u., respectively. © 1959, The Electrochemical Society, Inc. All rights reserved.