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

`C(s)+O_(2)(g)toCO_(2)(g),DeltaH^(0)=-393.5kJ*mol^(-1)` . . . (1)
`CO(g)+(1)/(2)O_(2)(g)toCO_(2)(g),DeltaH^(0)=-283.5kJ*mol^(-1)` . . . (2)
Subtracting equation (2) from equation (1) we get,
`C(s)+(1)/(2)O_(2)(g)toCO(g)`,
`DeltaH^(0)=[-393.5-(-283.5)]kJ*mol^(-1)`
`=-110.0kJ*mol^(-1)`
Therefore, the heat of formation of CO(g)
`=-11.0kJ*mol^(-1)`.