Question

Carbon and carbon monoxide burn in oxygen to form carbon dioxide according to the following reactions
`C+O_(2)rarrCO_(2), DeltaH=-394 " kJ mol"^(-1)`
`2CO+O_(2)rarr2CO_(2),DeltaH=-569 " kJ mol"^(-1)`
The heat of formation of 1 mol of carbon monoxide is thus
A. `-219.0 kJ mol^(-1)`
B. `-109.5 kJ mol^(-1)`
C. `-175.0 kJ mol^(-1)`
D. `-87.5 kJ mol^(-1)`

Answer 1

Correct Answer - B
`C+O_(2)rarrCO_(2)+394 kJ " ….(i)"`
`2C+2O_(2)rarr2CO_(2)+788 kJ " ….(ii)"`
`2CO_(2)+O_(2)rarr2CO_(2)+569 kJ " ….(iii)"`
`2CO_(2)rarr2CO+O_(2)-569 kJ " ….(iv)"`
eq. (ii) +eq. (iv) = - 109.5 kJ `mol^(-1)`.