Find the approximate value of ( ΔH - ΔU ) in J · mol - 1 , for the formation of CO from its…

$\mathrm{C}+\frac{1}{2}{\mathrm{O}}_2\to \mathrm{CO}$

$$\begin{gathered} {\mathrm{\Delta n}}_{\mathrm{g}}=\mathrm{Number} \mathrm{of} \mathrm{gaseous} \mathrm{products}-\mathrm{number} \mathrm{of} \mathrm{gaseous} \mathrm{reactants} \\ {\mathrm{\Delta n}}_{\mathrm{g}}=1-1-\frac{1}{2}=-\frac{1}{2} \end{gathered}$$

$\mathrm{R}=8.314 \mathrm{J}·{\mathrm{K}}^{-1}{ \mathrm{mol}}^{-1}$

Temperature $\mathrm{T}$=$298\mathrm{K}$

$$\begin{gathered} \mathrm{\Delta H}=\mathrm{\Delta U}-{\mathrm{\Delta n}}_{\mathrm{g}}\mathrm{RT} \\ \mathrm{\Delta H}-\mathrm{\Delta U}=-{\mathrm{\Delta n}}_{\mathrm{g}}\mathrm{RT} \\ \mathrm{\Delta H}-\mathrm{\Delta U}=\frac{1}{2}\times 8.314\times 298=1238 \end{gathered}$$

Hence, the value of $\left(\mathrm{\Delta H}-\mathrm{\Delta U}\right)$ is equal to the $1238$ $\mathrm{J}·{\mathrm{mol}}^{-1}$.