Question

A cell is prepared by dipping a copper rod in `1 MCuSO_(4)` solution and a nickel rod in `1M NiSO_(4)`. The standard reduction potentials of copper and nickel electrodes are `+0.34 V` and `-0.25 V` respectively.
(i) Which electrode will work as anode and which as cathode?
(ii) What will be the cell reaction?
(iii) How is the cell represented ?
(iv) Calculate the `EMF` of the cell.

Answer 1

(i) The nickel electrode with smaller `E^(@)` value `(-0.25V)` will work as anode while copper electrode with more `E^(@)` value `(+0.34V)` will work as cathode.
(ii) The cell reaction may be written as:
`{:("A anode", :, Ni(s) rarr Ni^(2+)(aq).+2e^(-)),("At cathode",:, Cu^(2+) (aq) +2e^(-) rarr Cu(s)),("Cell reaction",:, Ni(s) +Cu^(2+) (aq) rarr Ni^(2+)(aq) +Cu(s)):}`
The cell may be represented as:
`Ni(s)//Ni^(2+) (aq) || Cu^(2+)(aq)//Cu(s)`
(iv) `CMF` of cell `=E_("cathode") -E_("anode")^(@) =(+0.34) -(0.25) = 0.59V`