Question

$(\Delta H-\Delta U)$ in J/mol for the formation of carbon monoxide $\left(CO\right)$ from its elements at $300\text{K}$ is:$R=\frac{25}{3}\text{J/Kmol}$

Answer 1

$C\left(s\right)+\frac{1}{2}{O}_2\left(g\right)\to CO\left(g\right)$
$\Delta H=\Delta U+\Delta n_{g}RT$
$\Delta n_g=1-\frac{1}{2}=\frac{1}{2}$
$(\Delta H-\Delta U)=\frac{1}{2}\times \frac{25}{3}\times 300=1250\text{J/mol}$