The heat of formation of hydrogen chloride HCl can be calculated from the given enthalpy change of the reaction. The reaction is:2H2 g + Cl2 g -> 2HCl g The enthalpy change for this reaction is -184.6 kJ/mol. Since 2 moles of HCl are formed in the reaction, we can divide the enthalpy change by 2 to find the heat of formation for 1 mole of HCl:Heat of formation of HCl = -184.6 kJ/mol / 2 = -92.3 kJ/molSo, the heat of formation of hydrogen chloride HCl is -92.3 kJ/mol.