Which of the following occurs when an aqueous solution of sodium hydroxide is electrolysed using graphite electrodes?

Assessment: WAEC SSCE - Chemistry - 1994 (Objective) Subject: Chemistry

Question 1 Report

Which of the following occurs when an aqueous solution of sodium hydroxide is electrolysed using graphite electrodes?
Answer Details
When an aqueous solution of sodium hydroxide (NaOH) is electrolyzed using graphite electrodes, the following occurs: At the cathode (negative electrode), hydrogen gas is produced through the reduction of water molecules. This is because water has a lower reduction potential than Na+ ions in the solution. 2H2O(l) + 2e- -> H2(g) + 2OH-(aq) At the anode (positive electrode), the hydroxide ions (OH-) are oxidized to form oxygen gas and water molecules. This is because OH- ions have a higher oxidation potential than water molecules. 4OH-(aq) -> 2H2O(l) + O2(g) + 4e- Therefore, the correct option is (c) Oxygen gas is produced at the anode.
Read lesson note on Rates Of Chemical Reaction (JAMB)
Read lesson note on Electrolysis (JAMB)
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