Question

An aqueous solution of nickel (II) sulphate was electrolysed using nickel electrodes. Observe the diagram and answer the questions that follow:

1. What do you observe at the cathode and anode respectively?
2. Name the cation that remains as a spectator ion in the solution.
3. Which equation for the reaction at the anode is correct?
   1. \[\ce{Ni -> Ni^{2+} + 2e-}\]
   2. \[\ce{Ni + 2e- -> Ni^{2+}}\]
   3. \[\ce{Ni^{2+} -> Ni + 2e-}\]
   4. \[\ce{Ni^{2+} + 2e- -> Ni}\]

Answer 1

1. At the cathode: Ni²⁺ ions move towards the cathode and are discharged as neutral Ni atoms by gaining electrons. Thus, Ni is deposited at the cathode.
   At the anode: It diminishes in mass. Ni²⁺ ions are formed.
2. H⁺ ions.
3. \[\ce{Ni -> Ni^{2+} + 2e-}\]