Question

Why emf of daniel cell increase if molarity of zinc sulphate solution decreases?

Answer 1

The Daniell cell was invented by a British chemist, John Frederic Daniell. In the Daniell cell, copper and zinc electrodes are immersed in a solution of copper (II) sulfate (CuSO4 (aq)) and zinc (II) sulfate (ZnSO4 (aq)) respectively. The two half cells are connected through a salt bridge. Here zinc acts as anode and copper acts as cathode.

At the anode, zinc undergoes oxidation to form zinc ions and electrons.  The zinc ions pass into the solution. If the two electrodes are connected using an external wire, the electrons produced by the oxidation of zinc travel through the wire and enter into the copper cathode, where they reduce the copper ions present in the solution and form copper atoms that are deposited on the cathode.

The anodic reaction is represented as:



The cathodic reaction is represented as:



Total cell reaction is the sum of the two half cell reactions: