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