Consider the following data.
(i) \( 2\mathrm{Al(s)} + 6\mathrm{HCl(aq)} \rightarrow \mathrm{Al_2Cl_6(aq)} + 3\mathrm{H_2(g)} + 1200 \, \text{kJ} / \text{mol} \)
(ii) \( \mathrm{H_2(g)} + \mathrm{Cl_2(g)} \rightarrow 2\mathrm{HCl(g)} + 164 \, \text{kJ} / \text{mol} \)
(iii) \( \mathrm{HCl(g)} + \text{aq} \rightarrow \mathrm{HCl(aq)} + 83 \, \text{kJ} / \text{mol} \)
(iv) \( \mathrm{Al_2Cl_6(s)} + \text{aq} \rightarrow \mathrm{Al_2Cl_6(aq)} + 663 \, \text{kJ} / \text{mol} \)
The enthalpy of formation of anhydrous solid \( \mathrm{Al_2Cl_6} \) is:
