Electrolysis of copper sulphate

The electrolysis of copper sulphate

There are numbers of examples of electrolysis. The electrolysis of copper sulphate is just one.

Activity :: Demonstration :

The electrolysis of copper sulphate Two copper electrodes are placed in a solution of blue copper sulphate and are connected to a source of electrical current as shown in the diagram below. The current is turned on and the reaction is left for a period of time.

 

Electrolysis of copper sulphate

                                                                                               Electrolysis of copper sulphate

Observations:

  • The initial blue colour of the solution remains unchanged.
  • It appears that copper has been deposited on one of the electrodes but dissolved from the other.

Explanation:

  • At the negative cathode, positively charged Cu2+ ions are attracted to the negatively charged electrode. These ions gain electrons and are reduced to form copper metal, which is deposited on the electrode. The half-reaction that takes place is as follows:

       Cu2+(aq) + 2e− → Cu(s) (reduction half reaction)

  • At the positive anode, copper metal is oxidised to form Cu2+ ions. This is why it appears that some of the copper has dissolved from the electrode. The half-reaction that takes place is as follows:

       Cu(s) → Cu2+(aq) + 2e− (oxidation half reaction)

  • The amount of copper that is deposited at one electrode is approximately the same as the amount of copper that is dissolved from the other. The number of Cu2+ ions in the solution therefore remains almost the same and the blue colour of the solution is unchanged.

Conclusion:

In this demonstration, an electric current was used to split CuSO4 into its component ions, Cu2+ and SO2− 4.

This process is called electrolysis.

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