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Chemistry - Electrochemistry Question with Solution | TestHub

ChemistryElectrochemistryGalvanic cells/Nernst Equation/Concentration CellsMedium2 minPYQ_2018
ChemistryMediumnumerical

Consider an electrochemical cell: A s    A n+   aq, 2 M    B 2n+ aq, 1 M    B s . The value of ΔH o for the cell reaction is twice that of ΔG o at300 K.If the emf of the cell is zero, the magnitude ofΔSo in  J 1 K 1   mol 1 of the cell reaction per mole of B formed at 300K is ____
(Given: R=8.3JK1mol1. H,S and G are enthalpy, entropy and Gibbs energy, respectively.)

Answer:
-11.62
Solution:

A(s)| A +n (aq.2M)|| B +2n (aq.1M)|B(s)
ΔHo=2ΔGo    Ecell=0
CellReaction AA+n+ne×2
B +2n +2 ne B(s)
2A(s)+ B +2n 1M (aq) 2 A +n 2M (aq)+B(s)
ΔG= ΔG o +RTln A +n 2   B +2n
ΔG o =RTln A +n 2   B +2n =RT×ln 2 2 1 =RTln4
ΔG o = ΔH o TΔS o
ΔG o = 2ΔG o TΔS o
ΔS o = ΔG o T = RTln4 T
=8.3×2×0.7=-11.62 J/Kmol1

Stream:JEE_ADVSubject:ChemistryTopic:ElectrochemistrySubtopic:Galvanic cells/Nernst Equation/Concentration Cells
2mℹ️ Source: PYQ_2018

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