Chemistry 2002 JAMB Past Questions - Question 15: The products of the electrolysis of dilute sodium hydroxide using platinum electrodes are

Correct Answer

A

Explanation

The electrolysis of dilute sodium hydroxide (NaOH) using platinum electrodes typically results in the formation of hydrogen gas (H2) at the cathode and oxygen gas (O2) at the anode. The overall reaction can be represented as follows:

At the cathode (negative electrode):
\[2 \text{H}_2\text{O} + 2 \text{e}^- \rightarrow \text{H}_2 + 2 \text{OH}^-\]

At the anode (positive electrode):
\[4 \text{OH}^- \rightarrow \text{O}_2 + 2 \text{H}_2\text{O} + 4 \text{e}^-\]

The net reaction for the electrolysis of water in sodium hydroxide solution is the combination of the above two half-reactions:

\[2 \text{H}_2\text{O} \rightarrow \text{O}_2 + \text{H}_2\]

So, hydrogen gas is produced at the cathode, and oxygen gas is produced at the anode during the electrolysis of dilute sodium hydroxide with platinum electrodes.