Question

$△U^{\theta }$ of combustion of methane is -X kJ ${mol}^{-1}$. The value of $△H^{\theta }$ is:

• A. $=△U^{\theta }$
• B. $<△U^{\theta }$
• C. Zero
• D. $>△U^{\theta }$

Answer 1

The correct option is B $<△U^{\theta }$

Since $△H^{\theta }$ = $△U^{\theta }$ + $\Delta n_{g}RT$ and $△U^{\theta }$ = -X kJ $mo{l}^{-1}$

$△H^{\theta }$ = (-X) + $\Delta n_{g}RT$ $\Rightarrow$ $△H^{\theta }$ > $△U^{\theta }$

So the correct option is:

> $△U^{\theta }$