The enthalpies of combustion of carbon and carbon monoxide are -390 kJ and -278 kJ respectively. The enthalpy of formation of CO in kJ is

Question

The enthalpies of combustion of carbon and carbon monoxide are -390 kJ and -278 kJ respectively. The enthalpy of formation of CO in kJ is (A) 668 (B) 112 (C) -112 (D) -668

Tardigrade Admin · Accepted Answer

C+O2→ CO2; Δ H = -290 kJ ....(1) CO +(1/2)O2→ CO2; Δ H = -278 kJ ...(2) By eq. (1) and eq. (2), we get C+ (1/2)O2→ CO; Δ H = - 112 kJ

Q. The enthalpies of combustion of carbon and carbon monoxide are $- 390 k J$ and $- 278 k J$ respectively. The enthalpy of formation of $CO$ in $k J$ is

$668$

$112$

$- 112$

$- 668$

$C + O_{2} \to C O_{2}; Δ H = - 290 k J .... (1)$
$CO + \frac{1}{2} O_{2} \to C O_{2}; Δ H = - 278 k J ... (2)$
By eq. (1) and eq. (2), we get
$C + \frac{1}{2} O_{2} \to CO; Δ H = - 112 k J$

Q. The enthalpies of combustion of carbon and carbon monoxide are −390kJ and −278kJ respectively. The enthalpy of formation of CO in kJ is

668

112

−112

−668