Question

$(\Delta H-\Delta U)$ for the formation of carbon monoxide $\left(CO\right)$ from its elements at $298K$ is
$(R=8.314J{K}^{-1}{\text{mol}}^{-1})$

• A. $1238.78J{\text{mol}}^{-1}$
• B. $-2477.57J{\text{mol}}^{-1}$
• C. $2477.57J{\text{mol}}^{-1}$
• D. $-1238.78J{\text{mol}}^{-1}$

Answer 1

The correct option is A $1238.78J{\text{mol}}^{-1}$

$\Delta H-\Delta U=\Delta n_{g}RT$
$C\left(s\right)+\frac{1}{2}{O}_2\left(g\right)\to CO\left(g\right)$
$\Delta n_g=1-\frac{1}{2}=+\frac{1}{2}\Delta H-\Delta U=\frac{1}{2}\times 8.314\times 298=1238.78J{\text{mol}}^{-1}$