• # question_answer 58) ${{H}_{2}}+C{{l}_{2}}\to 2HCl,\Delta H=-194\,kJ$. In the above reaction the heat formation of HC1 is A)  +97 kJ                      B)  -97 kJC)  +10 kJ                      D)  -10 kJ

Heat of formation is the amount of heat absorbed or liberated when one mole of a substance is formed by its constituent element. When 2 moles of HCl is formed, the heat liberated =194 kJ. As when 1 mol of HC1 is formed the heat liberated $=\frac{194}{2}=97\,kJ$ So, $\Delta {{H}_{f}}=-97\,kJ.$ Hence, the correct option is [b].