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← JEE Main 2022 · 26 Jun · Shift 2
ChemistryInteger+4 / -1Question 87 of 90

JEE Main 2022 · 26 Jun · Shift 2, Chemistry question 87

Cu(s)+Sn2+(0.001M)→Cu2+(0.01M)+Sn(s)\mathrm{Cu(s)+Sn^{2+}(0.001M)\rightarrow Cu^{2+}(0.01M)+Sn(s)}
The Gibbs free energy change for the above reaction at 298 K is x×10−1x\times10^{-1} kJ mol−1^{-1}. The value of xx is ______. [nearest integer]

[Given : ECu2+/Cu⊖=0.34E^\ominus_{\mathrm{Cu^{2+}/Cu}}=0.34 V; ESn2+/Sn⊖=−0.14E^\ominus_{\mathrm{Sn^{2+}/Sn}}=-0.14 V; F=96500F=96500 C mol−1^{-1}]

Answer and worked solution

Official answer: 983

Standard emf. E°=−0.14−0.34=−0.48E°=-0.14-0.34=-0.48 V (n=2n=2).

Nernst. E=−0.48−0.0592log⁡0.010.001=−0.5095E=-0.48-\dfrac{0.059}2\log\dfrac{0.01}{0.001}=-0.5095 V.

Free energy. ΔG=−2×96500×(−0.5095)≈98.3\Delta G=-2\times96500\times(-0.5095)\approx98.3 kJ mol−1=983×10−1^{-1}=983\times10^{-1}.

Answer: 983