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Question
What is meant by ‘hydrated’ salts? Explain with examples.
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Solution
The water molecules which form part of the structure of a crystal (of a salt) are called water of crystallisation. Salts that contain water of crystallisation are called hydrated salts.
Copper sulphate crystals contain 5 molecules of water of crystallisation in one formula unit and therefore are written as CuSO4.5H2O. It is called copper sulphate pentahydrate (Pentahydrate means five molecules of water).
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