From the data at `25^(@)C`:
`Fe_(2)O_(3)(s) +3C_(("graphite")) rarr 2Fe(s) + 3CO(g), DeltaH^(Theta) = 492.0 kJ mol^(-1)`
`FeO(s) +C_(("graphite")) rarr Fe(s) +CO(g), DeltaH^(Theta) = 155.0 kJ mol^(-1)`
`C_(("graphite")) +O_(2)(g) rarr CO_(2)(g), DeltaH^(Theta) =- 393.0 kJ mol^(-1)`
`CO(g)+(1)/(2)O_(2)(g) rarr CO_(2)(g), DeltaH^(Theta) =- 282.0 kJ mol^(-1)`
Calculate the standard heat of formation of `FeO(s)` and `Fe_(2)O_(3)(s)`.

Explanation

`Fe(s)+CO(g)toFeO(s)+C("graphite"),DeltaH^(@)=-155.8kJ//mol`
`C("graphite")+O_(2)(g)toCO_(2)(g),DeltaH^(@)=-393.5kJ//mol`
`CO_(2)(g)toCO(g)+(1)/(2)O_(2)(g),DeltaH^(@)=282.98kJ//mol`
`overline(" On adding "Fe(s)+(1)/(2)O_(2)(g)toFeO(s)," "DeltaH=-266.3kJ//mol)`
Similarly we may calculate heat of formation of `Fe_(2)O_(3)`.