The enthalpies of combustion of carbon and carbon monoxide are -393.5 and -283 kJ mol−1 respectively. The enthalpy of formation of carbon monoxide per mole is

Question

The enthalpies of combustion of carbon and carbon monoxide are -393.5 and -283 kJ mol−1 respectively. The enthalpy of formation of carbon monoxide per mole is (A)  110.5 kJ  (B)  676.5 kJ  (C)  -676.5 kJ  (D)  -110.5 kJ

Tardigrade Admin · Accepted Answer

I: C(s) +O2(g) -> CO2(g) ;Δ H=-393.5 kJ II: CO(g) +(1/2) +O2(g) -> CO2(g) ; Δ H=-283.0 kJ I and II gives III: C(s) + (1/2) O2(g) -> CO(g) ; Δ H=-110.5 kJ This equation III also represents formation of 1 mole of CO and thus enthalpy change is the heat of formation of CO(g).

Q. The enthalpies of combustion of carbon and carbon monoxide are $- 393.5$ and $- 283 k J m o l^{- 1}$ respectively. The enthalpy of formation of carbon monoxide per mole is

$110.5 k J$

$676.5 k J$

$- 676.5 k J$

$- 110.5 k J$

Q. The enthalpies of combustion of carbon and carbon monoxide are −393.5 and −283kJmol−1 respectively. The enthalpy of formation of carbon monoxide per mole is

110.5kJ

676.5kJ

−676.5kJ

−110.5kJ

I: C(s)+OX2​(g)​COX2​(g) ;ΔH=-393.5kJ II: CO(g)+21​+OX2​(g)​COX2​(g);ΔH=-283.0kJ I and II gives III: C(s)+21​ OX2​(g)​CO(g);ΔH=-110.5kJ This equation III also represents formation of 1mole of CO and thus enthalpy change is the heat of formation of CO(g).

Q. The enthalpies of combustion of carbon and carbon monoxide are $- 393.5$ and $- 283 k J m o l^{- 1}$ respectively. The enthalpy of formation of carbon monoxide per mole is

$110.5 k J$

$676.5 k J$

$- 676.5 k J$

$- 110.5 k J$