Q37 / 120 · VITEEE 2011 · Chemistry
For the reaction,
$$
\mathrm{C}_{3} \mathrm{H}_{8}(\mathrm{~g})+5 \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow 3 \mathrm{CO}_{2}(\mathrm{~g})+4 \mathrm{H}_{2} \mathrm{O}(\mathrm{l})
$$
at constant temperature, $\Delta \mathrm{H}-\Delta \mathrm{E}$ is
- A$\mathrm{RT}$
- Correct answerB$-3 R T$
- C$3 R T$
- D$-\mathrm{RT}$
Solution
$$
\begin{array}{l}
\mathrm{C}_{3} \mathrm{H}_{8}(\mathrm{~g})+5 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow 3 \mathrm{CO}_{2}(\mathrm{~g})+4 \mathrm{H}_{2} \mathrm{O}(l) \\
\begin{array}{l}
\Delta \mathrm{n}_{\mathrm{g}}=\mathrm{n}_{\mathrm{p}}-\mathrm{n}_{\mathrm{r}} \\
=3-6=-3
\end{array} \\
\begin{array}{l}
\Delta \mathrm{H}=\Delta \mathrm{E}+\Delta \mathrm{n}_{\mathrm{g}} \mathrm{RT} \\
\Delta \mathrm{H}=\Delta \mathrm{E}-3 \mathrm{RT} \\
\Delta \mathrm{H}-\Delta \mathrm{E}=-3 \mathrm{RT}
\end{array}
\end{array}
$$
Hence, the correct answer is option: 'B'.