Question

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 :

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

Answer 1

Answer: (D)

-110.5

Answer 2

$C _{( g )}+ O _{2( g )} \longrightarrow CO _{2( g )} \,\,\,\,\,\,\,\, \Delta H _{1}=-393.5\, kJ /\, mol$ $CO _{( g )}+\frac{1}{2} O _{2( g )} \longrightarrow CO _{2}( g ) \,\,\,\,\,\,\,\, \Delta H _{2}=-283.5\, kJ /\, mol$ $C _{( g )}+\frac{1}{2} O _{2( g )} \longrightarrow CO _{( g )} \,\,\,\,\,\,\,\,\Delta H =\Delta H _{1}-\Delta H _{2}=-110 \,kJ\, / mol$