Chemistry · Thermodynamics & Thermochemistry

JEE Main 2026 — 4 April, Evening Shift — Question 63

For the following reaction at 50∘C50^{\circ} \mathrm{C} and 2 atm pressure, 2 N2O5( g)⇌2 N2O4( g)+O2( g)2 \mathrm{~N}_{2} \mathrm{O}_{5}(\mathrm{~g}) \rightleftharpoons 2 \mathrm{~N}_{2} \mathrm{O}_{4}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g}) N2O5\mathrm{N}_{2} \mathrm{O}_{5} is 50%50 \% dissociated The magnitude of standard free energy change at this temperature is x . x=\mathrm{x}= ____\_\_\_\_ Jmol−1\mathrm{J} \mathrm{mol}^{-1} [Nearest integer] Given : R=8.314 mol−1 K−1,log⁡2=0.30\mathrm{R}=8.314 \mathrm{~mol}^{-1} \mathrm{~K}^{-1}, \log 2=0.30, log⁡3=0.48,ln⁡10=2.303,∘C+273=K\log 3=0.48, \ln 10=2.303,{ }^{\circ} \mathrm{C}+273=\mathrm{K}

Answer: 2474

Numerical answer — enter this value.

Step-by-step solution

2 N2O5(q)⇌2 N2O4( g)+O2( g)\quad 2 \mathrm{~N}_{2} \mathrm{O}_{5}(\mathrm{q}) \rightleftharpoons 2 \mathrm{~N}_{2} \mathrm{O}_{4}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g})

t=0 & 1 & - \\ t_{\text{eqm.}} & 1-2x & 2x & x \\ & 1-0.5 & 0.5 & 0.25 \\ & 0.5 & 0.5 & 0.25 \\ & \dfrac{0.5}{1.25}\times 2 & \dfrac{0.5}{1.25}\times 2 & \dfrac{0.25}{1.25}\times 2 \end{array}$$$ $$ \begin{aligned} \mathrm{K}_{\mathrm{P}} & =\frac{\mathrm{P}_{\mathrm{N}_{2} \mathrm{O}_{4}}^{2} \cdot \mathrm{P}_{\mathrm{O}_{2}}}{\mathrm{P}_{\mathrm{N}_{2} \mathrm{O}_{5}}^{2}}=0.4 \Delta \mathrm{G}^{\circ} & =-2.303 \mathrm{RT} \log \mathrm{~K}_{\mathrm{p}} & =-2.303 \times 8.314 \times 323 \log (4 / 10) & =2473.81 \mathrm{~J} / \mathrm{mole} \end{aligned} $$

Answer key and solution verified before publishing.

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Exam
JEE Main 2026
Subject
Chemistry
Chapter
Thermodynamics & Thermochemistry
Topic
Gibbs Free Energy - Relation with Equilibrium, Metallurgy and Electrochemistry
For the following reaction at 50 ° C and 2 atm pressure, 2 N 2 O 5 (… | JEE Main 2026 PYQ with Solution · DhiX AI