• # question_answer 57)   Standard molar enthalpy of formation, ${{\Delta }_{f}}{{H}^{O-}}$ is just a special case of enthalpy of reaction${{\Delta }_{r}}{{H}^{O-}}$. Is the${{\Delta }_{r}}{{H}^{O-}}$for the following reaction same as${{\Delta }_{f}}{{H}^{O-}}$? Give reason for your answer. $CaO(s)+C{{O}_{2}}(g)\to CaC{{O}_{3}}(s);$      ${{\Delta }_{f}}{{H}^{O-}}=-178.3\,kJ\,mo{{l}^{-1}}$

The reaction: $CaO(s)+C{{O}_{2}}(g)\to CaC{{O}_{3}}(s)$ It is not the equation of formation of $CaC{{O}_{3}}(s)$. Formation is the process in which a compound is formed from its constituent elements in their standard state.