The enthalpies of combustion of carbon and carbon monoxide are `-393.5` and `-283` kJ `mol^(-1)` respectively. The enthaly of formation of carbon monoxide per mole is :

Options

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

Answer

B

Explanation

`(i) C+O_(2)toCO_(2)`, `DeltaH=-393.5 kJ`
`(ii) CO+(1)/(2)O_(2)toCO_(2)`, `DeltaH=-283 kJ`
` C+(1)/(2)O_(2)toCO`, `DeltaH=?`
Solve `(i)-(ii)`
`:. DeltaH=(-393.5)-(-283)kJ`
`=(-393.5+283)kJ=-110.5 kJ`