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Electrochemistry

Question
CBSEENCH12005997

Calculate emf of the following cell at 298 K
Mg(s) | Mg2+ (0.001 M) || Cu2+ (0.0001 M) | Cu(s)
(Given : E°Cu2/Cu = + 0.34 V; E° Mg2+/Mg = – 2.37 V)

Solution
Mg(s)  Mg2+ + 2e-
Cu2+ + 2e-  Cu(s)The overall net reaction Mg(s) +Cu2+  Mg2+ +Cu(s)Ecell =Ecell0 - 2.303nFRT log[Mg2+][Cu2+]Ecell =ECu2+Cu0  - Emg2+mg0  = +0.34V -(-2.37V) =+2.71VEcell =2.71-0.05912×log10Ecell  =2.71V-0.0295Ecell  = 2.6805V