Enthaples of formation of `CO(g), CO_(2)(g), N_(2)O (g) and N_(2)O_(4) (g)` are - 110, - 393, 81 and `9.7 kj mol^(-1)` respectively. Find the value of `Delta H` for the reaction:
`N_(2)O_(4) (g) + 3CO(g) to N_(2) O(g) + 3 CO_(2) (g)`

Explanation

We are given that
`H_(f) [CO(g)] = - 110 kj mol^(-1)`
`H_(f) [CO_(2)(g)]=-393 mol^(-1)`
`H_(f) [N_(2)O(g) = 81 kj mol^(-1)`
`H_(f)[N_(2)O_(4)(g)] = 9.7 kJ mol^(-1)`
We are to calculate the value of `Delta_(r)H`.
`N_(2)O_(4)(g) + 3CO(g) to N_(2) (O) (g) +3 CO_(2) (g)`
We know that
`Delta H = H_(f) [N_(2)O(g)]+3H_(f)[CO_(2)(g)]-H_(f)[(N_(2)O_(4)(g)] - 3H_(f) [CO(g)]`
` = 81 - 1179 - 9.7 + 330 = 777.7 kj mol^(-1)`