Thermodynamics And Thermochemistry Result Question 12
The $\Delta H_f^{\circ}$ for $\mathrm{CO}_2(g), \mathrm{CO}(g)$ and $\mathrm{H}_2 \mathrm{O}(g)$ are $-393.5,-110.5$ and $-241.8 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively. The standard enthalpy change (in $\mathrm{kJ} $ $\mathrm{mol}^{-1}$ ) for the reaction $\mathrm{CO}_2(g)+\mathrm{H}_2(g) \longrightarrow \mathrm{CO}(g)+\mathrm{H}_2 \mathrm{O}(g)$ is
(2000, 1M)
(a) $524.1$
(b) $+41.2$
(c) $-262.5$
(d) $-41.2$
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Answer:
Correct Answer: 12. ( b )
Solution:
- $\mathrm{CO}_2(g)+\mathrm{H}_2(g) \longrightarrow \mathrm{CO}(g)+\mathrm{H}_2 \mathrm{O}(g) $
$\Delta H =\Sigma \Delta_f H^{\circ} \text { (products) }-\Sigma \Delta_f H^{\circ} \text { (reactants) } $
$ =-110.5-241.8-(-393.5)=+41.20 \mathrm{~kJ}$
BETA
