Q11 / 160 · AP EAMCET 2024 (22 May Shift 1) · Chemistry
At equilibrium for the reaction
$\mathrm{A}_2(g)+\mathrm{B}_2(g) \rightleftharpoons 2 \mathrm{AB}(g)$
the concentrations of $\mathrm{A}_2, \mathrm{~B}_2$ and AB respectively are $1.5 \times 10^{-3} \mathrm{M}, 2.1 \times 10^{-3} \mathrm{M}$ and $1.4 \times 10^{-3} \mathrm{M}$ in a sealed vessel at 800 K . What will be $\mathrm{K}_{\mathrm{p}}$ for the decomposition of AB at same temperature?
- A0.62
- Correct answerB1.6
- C0.44
- D2.27
Solution
$\begin{aligned}
& \text { } \mathrm{A}_2(\mathrm{~g})+\mathrm{B}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{AB}(\mathrm{~g}) \\
& \mathrm{K}_{\mathrm{c}}=\frac{[\mathrm{AB}]^2}{\left[\mathrm{~A}_2\right]\left[\mathrm{B}_2\right]} \\
& \mathrm{K}_{\mathrm{c}}=\frac{1.4 \times 10^{-3} \times 1.4 \times 10^{-3}}{1.5 \times 10^{-3} \times 2.1 \times 10^{-3}} \\
& \mathrm{~K}_{\mathrm{c}}=0.622 \\
& \mathrm{~K}_{\mathrm{p}}=\mathrm{K}_{\mathrm{c}} \mathrm{x}(\mathrm{RT})^{\Delta \mathrm{n}} \\
& \Delta \mathrm{n}=0 \\
& \mathrm{~K}_{\mathrm{p}}=\mathrm{K}_{\mathrm{c}}=0.622
\end{aligned}$
$\begin{aligned}
\mathrm{K}_{\mathrm{p}} \text { for the decomposition of } \mathrm{AB}\left(\mathrm{~K}^{\prime}\right) & =\frac{1}{\mathrm{~K}_{\mathrm{p}}} \\
& =\frac{1}{0.622} \\
\mathrm{~K}^{\prime} & =1.60
\end{aligned}$
Hence, the correct answer is option: 'B'.