Answer
(a) $–196.0\text{ kJ·mol}^{-1}$; exothermic
(b)$ –100.7\text{ kJ·mol}^{-1}$; exothermic
(c) $–902.0\text{ kJ·mol}^{-1}$; exothermic
Work Step by Step
The $\Delta H^{\circ}_{f}$ value can be taken by subtracting initial enthalpy from the final using the given values,
$\Delta H^{\circ}_{f} = H^{\circ}_{f} Final-H^{\circ}_{f}Initial$
When the sign of the enthalpy change is negative reaction is exothermic as energy is released, when sign is positive reaction is endothermic as energy is absorbed
(a) $–196.0\text{ kJ·mol}^{-1}$; exothermic
(b)$ –100.7\text{ kJ·mol}^{-1}$; exothermic
(c) $–902.0\text{ kJ·mol}^{-1}$; exothermic
