Standard molar enthalpy of formation, `Delta_(f) H^(Θ)` is just a special case of enthalpy of reaction, `Delta_(r) H^(Θ)`. Is the `Delta_(r) H^(Θ)` for the following reaction same as `Delta_(f) H^(Θ)`? Given reason for your answer.
`CaO (s) + CO_(2) (g) rarr CaCO_(3) (s) , Delta_(f) H^(Θ) = - 178.3 kJ mol^(-1)`

Explanation

No, because enthalpy of formation is the enthalpy change when 1 mole of the compound is formed from the elements , i.e., for the reaction `Ca(s) + C(s) + (3)/(2) O_(2)(g) rarr CaCO_(3)(s)`. Thus, this reaction is different from the givien reaction. Hence, `Delta_(r) H^(@) cancel(=) Delta_(f)H^(@)`.