Question
State your observation for the following electrolytic reaction
Aqueous copper sulphate is electrolysed between copper electrodes.
Aqueous copper sulphate is electrolysed between copper electrodes.
✓
Answer
When Aqueous copper sulphate is electrolysed between copper electrodes then the ions formed are
$\ce{CuSO4 ⇌ Cu^{+2} + SO^{-2}_{4}}$
$\ce{H2O ⇌ H+ + OH-}$
Reaction at the Cathode : Copper and hydrogen ions both being positively charged migrate towards the cathode, Copper ions are discharged in preference to hydrogen ions, Copper gains two electrons from the cathode and changes into an atom of copper, The atoms of copper are deposited at the cathode, The atoms of copper are deposited at the cathode ad form a layer of pink copper metal which gradually turns reddish brown.
$\ce{Cu^{+2} + 2e- -> Cu}$
Reaction at the anode : Anode receives electrons from the ions and supplies them to the cathode, The atoms of copper from the anode changes into ions of copper which go into the solution and the electrons liberated in this change are taken up by the anode.
$\ce{Cu - 2e- -> Cu^{+2}}$
Thus for every copper ion discharged at the cathode, an ion of copper is formed at the anode which goes into the solution, Thus the atoms of copper are deposited at the cathode, the cathode becomes thicker and the atoms of
copper from the anode change into ions of copper, the anode becomes thinner.
Therefore there is transference of copper atoms from anode to cathode.
$\ce{CuSO4 ⇌ Cu^{+2} + SO^{-2}_{4}}$
$\ce{H2O ⇌ H+ + OH-}$
Reaction at the Cathode : Copper and hydrogen ions both being positively charged migrate towards the cathode, Copper ions are discharged in preference to hydrogen ions, Copper gains two electrons from the cathode and changes into an atom of copper, The atoms of copper are deposited at the cathode, The atoms of copper are deposited at the cathode ad form a layer of pink copper metal which gradually turns reddish brown.
$\ce{Cu^{+2} + 2e- -> Cu}$
Reaction at the anode : Anode receives electrons from the ions and supplies them to the cathode, The atoms of copper from the anode changes into ions of copper which go into the solution and the electrons liberated in this change are taken up by the anode.
$\ce{Cu - 2e- -> Cu^{+2}}$
Thus for every copper ion discharged at the cathode, an ion of copper is formed at the anode which goes into the solution, Thus the atoms of copper are deposited at the cathode, the cathode becomes thicker and the atoms of
copper from the anode change into ions of copper, the anode becomes thinner.
Therefore there is transference of copper atoms from anode to cathode.
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