As we expected from earlier.Example:What isεfor a Daniel cell at 300 K when theconcentration of Cu2+is 0.100 M and the concentration of Zn2+is 0.001 M?Zn(s) + Cu2+(aq)→Cu(s) + Zn2+(30.6)First we needε°which we found last lecture to be 1.10 V.Then we use the Nernst equation,ε=1.10−8.314×3002×96485ln0.1000.001=1.04VThen= 2because 2 electrons are transferred from the zinc tothe copper during the reaction.Notice that even though the concentrations differ by a factorof 100, the difference in voltage from the standard potential isminimal.Group Work1. Explicitly derive the Nernst equation from the4Gequa-tion.2. What isKfor the Daniels cell reaction?
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