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)`? 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, the `Delta_(f)H^(Θ)` for the given reaction is not same as `Delta_(f) H^(Θ)`. The standard enthalpy change for the formation of one mole of a compound from its elements in their most stable states (reference states) is called standard molar enthalpy of formation, `Delta(f) H^(Θ)`.
`Ca(s) + C(s) + (3)/(2) O_(2) (g) rarr CaCO_(3) (s) , Delta(f) H^(Θ)`.
This reaction is different from the given reaction.
Hence, `Delta_(f) H^(@) != Delta_(f)H^(@)`