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JAMB Chemistry 2023 Paper

Question : 24

Total: 82

What is the product of the electrolysis of aqueous sodium chloride (NaCl) using inert electrodes?

Hydrogen gas at the cathode and chlorine gas at the anode
Hydrogen gas at the cathode and oxygen gas at the anode
Sodium metal at the cathode and chlorine gas at the anode
Sodium metal at the cathode and oxygen gas at the anode

Solution:

Concept:

Electrolysis of aqueous sodium chloride with inert electrodes produces hydrogen and chlorine gases because water and chloride ions are discharged instead of sodium ions.

Explanation:

At the cathode,

H^+

ions from water are reduced to hydrogen gas:

2H_2O + 2e^- \rightarrow H_2 + 2OH^-

At the anode,

Cl^-

ions are oxidised to chlorine gas:

2Cl^- \rightarrow Cl_2 + 2e^-

Sodium ions remain in solution because water is more readily reduced than sodium ions.

Therefore, hydrogen gas is produced at the cathode and chlorine gas is produced at the anode.

Answer:

A. Hydrogen gas at the cathode and chlorine gas at the anode.

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