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

Options

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

Answer

C

Explanation

Given`: C(s) + O_(2)(g) rarr CO_(2)(g), DeltaH = -393.5 kJ mol^(-1)` …(i)
`CO(g) + (1)/(2) O_(2)(g) rarr CO_(2)(g), DeltaH= - 283.5 kJ mol^(-1)` …(ii)
Aim `: C(s) + (1)/(2)O_(2)(g)rarr CO(g)`
Eqn. (i) -Eqn. (ii) gives required eqn. with `DeltaH =- 393.5 - ( - 283.5) kJ = -110 kJ`