The heats of combustion of carbon and carbon monoxide are -393.5 and `-283.5 kJ "mol"^(-1)` respectively. The heat of formation (in kJ) of carbon monoxide per mole is

Options

A. `110.5`
B. `676.5`
C. `-676.5`
D. `-110.5`

Answer

D

Explanation

(i) `C(s) +O_(2)(g) to CO_(2)(g) DeltaH = -393.5 kJ "mol"^(-1)`
(ii) `CO(g) + 1/2 O_(2)(g) to CO_(2)(g) DeltaH = -283.5 kJ "mol"^(-1)`
Subtracting equation (ii) from equation (i)
`C(s) + 1/2O_(2)(g) to CO(g) = - 110.0 kJ "mol"^(-1)`.