Question

When zeolite, which is hydrated sodium aluminium silicate, is treated with hard water the sodium ions are exchanged with

• A. $H^{+}$ ions
• B. $C{a}^{2+}$ ions
• C. $M{g}^{2+}$ ions
• D. (b) and (c) above.

Answer 1

The correct option is D (b) and (c) above.

Permutit or zeolites are packed in a suitable container and a slow stream of hard water is passed through this material. As a result, calcium and magnesium ions present in hard water are exchanged with sodium ions in the permutit (Na+Al-Silicate). The outgoing water contains sodium salts, which do not cause hardness.