JEE Main 2021 — Chemistry Physical Chemistry

2021integereasy

The gas phase reaction

$2A(g)\rightleftharpoons {A}_{2}(g)$

at $400K$ has $\Delta {G}^{o}=+25.2\mathrm{kJ}{\mathrm{mol}}^{-1}$ .

The equilibrium constant ${K}_{C}$ for this reaction is ___ $\times {10}^{-2}$ . (Round off to the Nearest integer)

Use : $R=8.3J{\mathrm{mol}}^{-1}{K}^{-1},\mathrm{ln}10=2.3 {\mathrm{log}}_{10}2=0.30,1\mathrm{atm}=1\mathrm{bar}$

antilog $(-0.3)=0.501$

Official previous-year question

Held on 18 Mar 2021 · Verified 6 Jul 2026.

Did you get this right?

Solution

Using formula

${\Delta }_{r}{G}^{0}=-{\mathrm{RTlnK}}_{p}$

$25200=-2.3\times 8.3\times 400\mathrm{log}({K}_{p})$

${K}_{p}={10}^{-3.3}={10}^{-3}\times 0.501$

$=5.01\times {10}^{-4}{\mathrm{Bar}}^{-1}$

$=5.01\times {10}^{-9}{\mathrm{Pa}}^{-1}$

$=\frac{{K}_{C}}{8.3\times 400}$

${K}_{C}=1.66\times {10}^{-5}{m}^{3}/\mathrm{mole}$

$=1.66\times {10}^{-2}L/\mathrm{mol}$

$=2$

Gibbs free energy can be visualized as the amount of useful energy present in a thermodynamic system that can be utilized to perform some useful work.

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JEE Main 2021 — Chemistry Physical Chemistry

2021integereasy

The gas phase reaction

$2A(g)\rightleftharpoons {A}_{2}(g)$

at $400K$ has $\Delta {G}^{o}=+25.2\mathrm{kJ}{\mathrm{mol}}^{-1}$ .

The equilibrium constant ${K}_{C}$ for this reaction is ___ $\times {10}^{-2}$ . (Round off to the Nearest integer)

Use : $R=8.3J{\mathrm{mol}}^{-1}{K}^{-1},\mathrm{ln}10=2.3 {\mathrm{log}}_{10}2=0.30,1\mathrm{atm}=1\mathrm{bar}$

antilog $(-0.3)=0.501$

Official previous-year question

Held on 18 Mar 2021 · Verified 6 Jul 2026.

Did you get this right?

Solution

Using formula

${\Delta }_{r}{G}^{0}=-{\mathrm{RTlnK}}_{p}$

$25200=-2.3\times 8.3\times 400\mathrm{log}({K}_{p})$

${K}_{p}={10}^{-3.3}={10}^{-3}\times 0.501$

$=5.01\times {10}^{-4}{\mathrm{Bar}}^{-1}$

$=5.01\times {10}^{-9}{\mathrm{Pa}}^{-1}$

$=\frac{{K}_{C}}{8.3\times 400}$

${K}_{C}=1.66\times {10}^{-5}{m}^{3}/\mathrm{mole}$

$=1.66\times {10}^{-2}L/\mathrm{mol}$

$=2$

Gibbs free energy can be visualized as the amount of useful energy present in a thermodynamic system that can be utilized to perform some useful work.

JEE Main 2021 — Chemistry Physical Chemistry

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Solution

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JEE Main Physical Chemistry in other years

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JEE Main 2021 — Chemistry Physical Chemistry

Did you get this right?

Solution

Your note

JEE Main Physical Chemistry in other years

More JEE Main Physical Chemistry questions

Other Chemistry topics for JEE Main

Organic Chemistry

Inorganic Chemistry

Keep practicing Physical Chemistry