11. What is second-order transition? (4%)

3. Using the following data, calculate the standard heat of formation of the compound ICl in kJ/mol: (4%) \( Cl_2(g) \rightarrow 2Cl(g) \) \( \Delta H^{\circ} = 242.3 \) kJ/mol \( I_2(g) \rightarrow 2I(g) \) \( \Delta H^{\circ} = 151.0 \) kJ/mol \( ICl(g) \rightarrow I(g) + Cl(g) \) \( \Delta H^{\circ} = 211.3 \) kJ/mol \( I_2(s) \rightarrow I_2(g) \) \( \Delta H^{\circ} = 62.8 \) kJ/mol