For a gaseous phase reactionWhen equilibrium is set up, K = 0.33Energy involved (in kJ) is

Cis ⇌ Trans Initial 1 0At equilib. (1 - x) xK=x1−x=0.333=13∴ x = 0.25Thus, there is 25% conversion into trans-form.∴ΔrH∘( net )=2.38×0.25=0.595kJ