37.8 g N 2 O 5 was taken in a 1 L reaction vessel and allowed to undergo the following reaction at 500 K 2 N 2 O 5( g ) rightarrow 2 N 2 O 4( g ) + O 2( g ) The total pressure at equilibrium was found to be 18.65 bar. Then, Kp = × 10 -2 [nearest integer] Assume N 2 O 5 to behave ideally under these conditions Given : R =0.082 bar L mol -1 K -1

Chemistry · Chemical Equilibrium

JEE Main 2025 — 24 January, Morning Shift — Question 42

$\quad 37.8 \mathrm{~g} \mathrm{~N}_{2} \mathrm{O}_{5}$ was taken in a 1 L reaction vessel and allowed to undergo the following reaction

at 500 K $2 \mathrm{~N}_{2} \mathrm{O}_{5(\mathrm{~g})} \rightarrow 2 \mathrm{~N}_{2} \mathrm{O}_{4(\mathrm{~g})}+\mathrm{O}_{2(\mathrm{~g})}$

The total pressure at equilibrium was found to be 18.65 bar.

Then, $\mathrm{Kp}=$ ___ $\times 10^{-2}$ [nearest integer] Assume $\mathrm{N}_{2} \mathrm{O}_{5}$ to behave ideally under these

conditions

Given : $\mathrm{R}=0.082$ bar $\mathrm{L} \mathrm{mol}^{-1} \mathrm{~K}^{-1}$

Numerical answer — enter this value.

Initial pressure of $\mathrm{N}_{2} \mathrm{O}_{5}$

=\frac{\frac{37.8}{108} \times 0.082 \times 500}{1}=14.35 \mathrm{bar}

2 \mathrm{~N}_{2} \mathrm{O}_{5} \rightleftharpoons 2 \mathrm{~N}_{2} \mathrm{O}_{4}+\mathrm{O}_{2}

$\mathrm{t}=0$ 14.35

$\mathrm{t}=\mathrm{eq} \quad 14.35-2 \mathrm{P} \quad 2 \mathrm{P} \quad \mathrm{P}$

$\mathrm{P}_{\text {Total }}$ at $\mathrm{eqb}=14.35+\mathrm{P}=18.65$

$\mathrm{P}=4.3$

$\mathrm{P}_{\mathrm{N}_{2} \mathrm{O}_{5}}=5.75 \mathrm{bar}$

$\mathrm{P}_{\mathrm{N}_{2} \mathrm{O}_{4}}=8.6 \mathrm{bar}$ $\mathrm{P}_{\mathrm{O}_{2}}=4.3 \mathrm{bar}$

$\mathrm{k}_{\mathrm{p}}=\frac{(8.6)^{2} \times(4.3)}{(5.75)^{2}}=9.619=\mathrm{x} \times 10^{-2}$

$\mathrm{x}=961.9 \approx 962$

Answer key and solution verified before publishing.

Start with this question, then two more from the same chapter — with a tutor that explains every step. Free.

Exam: JEE Main 2025
Paper: 24 January, Morning Shift
Subject: Chemistry
Chapter: Chemical Equilibrium
Topic: Analysis of Chemical Equilibrium, Equilibrium Constant and Reaction Quotient