Test Index

WAEC Chemistry 2022 Paper

Question : 10

Total: 50

Anode Cathode

Solution:

Concept:

In electrolysis, the products depend on which ions are preferentially discharged at each electrode.

Explanation:

In dilute

\mathrm{NaCl}

, water provides both

H^+

and

OH^-

ions.

At the cathode,

H^+

ions are discharged to form hydrogen gas:

2H^+ + 2e^- \rightarrow H_2

At the anode,

OH^-

ions are discharged in preference to

Cl^-

because chloride ions are present at low concentration.

The

OH^-

ions lose electrons and form oxygen gas and water:

4OH^- \rightarrow 2H_2O + O_2 + 4e^-

Therefore, the anode produces oxygen, and the cathode produces hydrogen.

Answer:

Option B: oxygen and hydrogen.

Go to Question:

Prev Question

Next Question