Question

The heat of formation of $CO(g)$ and $C{{O}_{2}}(g)$ are $\Delta H=-110$ and $\Delta H=-393\,\,kJ\,\,mo{{l}^{-1}}$ respectively. What is the heat of reaction $(\Delta H)$ (in $kJ\,\,mo{{l}^{-1}})$ for the following reaction? $CO(g)+\frac{1}{2}{{O}_{2}}(g)\xrightarrow{{}}C{{O}_{2}}(g)$

• A. $-504$
• B. $-142.5$
• C. $-283$
• D. $504$

Answer 1

Answer: (C)

$-283$

Answer 2

$C+\frac{1}{2}{{O}_{2}}\xrightarrow{{}}CO,\,\,\Delta H=-110\,\,kJ\,\,mo{{l}^{-1}}$ ? (i) $C+{{O}_{2}}\xrightarrow{{}}C{{O}_{2}},\,\,\Delta H=-393\,\,kJ\,\,mo{{l}^{-1}}$ ... (ii) On subtracting Eq (i) from eq (ii), we get $CO+\frac{1}{2}{{O}_{2}}\xrightarrow{{}}C{{O}_{2}}$ $\Delta H=393-(-110)$ $=-283\,\,kJ\,\,mo{{l}^{-1}}$