Question: If E° for copper electrode is +0.34 V, how will you calculate its emf value when the solution in contact with it is 0.1 M in copper ions? How does emf for copper electrode change when concentration of Cu2+ ions in the solution is decreased?
Solution: The emf of an electrode when dipped in different concentrated solution is given by by the Nernst equation:
n is the number of electrons involved in the equation, i.e., 2
Cu2+ + 2e– → Cu
Substituting the given values in the Nernst equation, we get
When concentration of Cu2+ ion in solution decreases the emf of the electrode decreases.
In that case, it has decreased from 0.34 V to 0.3105 V.
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