Question

For $N_2\left(g\right)+2H_2\left(g\right)\rightleftharpoons 2N{H}_3\left(g\right)$, $\Delta H$ is equal to:

• A. $\Delta U+2RT$
• B. $\Delta U-2RT$
• C. $\Delta U-RT$
• D. $\Delta U+RT$

Answer 1

The correct option is B $\Delta U-2RT$

We know, $\Delta H=\Delta U+\Delta n_{g}RT$
where $\Delta H$ = change in enthalpy of the reaction
$\Delta U$ = Change in internal energy
$\Delta n_g$ = difference in moles of products and reactants = $2-4=-2$
$\Delta H$ = $\Delta U-2RT$