Question

For the reaction,
$N_2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2N{H}_3\left(g\right),△H$ is equal to :
($△U$ = change in internal energy)

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

Answer 1

The correct option is B $△U-2RT$

We know that,
$△H=△U+△n_{g}RT$
For the reaction:
$N_2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2N{H}_3\left(g\right)$
$△n_g=2-4=-2$
$△H=△U+△n_{g}RT$
$△H=△U+(-2)RT$
$△H=△U-2△RT$