Permanent hardness of water is caused by the presence of dissolved salts of calcium (Ca²⁺) and magnesium (Mg²⁺), particularly their sulphates (like CaSO₄ and MgSO₄). Unlike temporary hardness, which can be removed by boiling, permanent hardness cannot be eliminated by... Read More
Permanent hardness of water is caused by the presence of dissolved salts of calcium (Ca²⁺) and magnesium (Mg²⁺), particularly their sulphates (like CaSO₄ and MgSO₄). Unlike temporary hardness, which can be removed by boiling, permanent hardness cannot be eliminated by heating because these salts do not precipitate easily.
To remove permanent hardness, zeolites are commonly used. Zeolites are natural or synthetic aluminosilicate minerals that act as ion-exchange materials. When hard water passes through zeolites, the calcium and magnesium ions responsible for hardness are exchanged with sodium ions in the zeolite structure. This process effectively softens the water without the need for boiling or chemical precipitation.
Other options in the MCQ are incorrect:
Sulphonides are not used in water softening.
Lime (Ca(OH)₂) is effective only for removing temporary hardness, not permanent hardness caused by sulphates.
Nitrates have no role in softening water.
Understanding permanent hardness and its removal is important in water treatment, industrial processes, and daily life, as hard water can cause scale formation in boilers, reduce soap efficiency, and damage plumbing. Zeolite-based softeners are widely used in household water filters and industrial water treatment plants because they are reusable, eco-friendly, and efficient.
This concept demonstrates how chemistry principles, such as ion exchange, are applied in real-world solutions. It connects inorganic chemistry knowledge with practical applications, helping students understand both the problem (permanent hardness) and its scientific solution using zeolites.
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