The enthalpy changes for the following processes are listed below:
Cl2(g)→2Cl(g); 242.3kJ mol−1
I2(g)→2I(g); 151.0kJmol −1
ICl(g)→I(g)+Cl(g); 211.3kJ mol−1
I2(s)→I2(g); 62.76kJmol −1
Given that the standard states for iodine and chlorine are I2 (s) and Cl2(g) , the standard enthalpy of formation of ICl (g) is :