Question

A substance which on cooling does not gives out crystals.​

Answer 1

Answer:

Crystallization - Organic Chemistry

This simplified scientific description of crystallization does not give a realistic picture ... During this cooling, each solute molecule in turn approaches a growing crystal ... After a while, crystals should appear in the flask.

Answer 2

Explanation:

• Crystals of a substance which changed their colour on heating in a closed test tube but regained it after sometime when they were allowed to cool down are copper sulphate or more specifically hydrated copper sulphate.
• Crystals of a substance which changed their colour on heating in a closed test tube but regained it after sometime when they were allowed to cool down are copper sulphate or more specifically hydrated copper sulphate.Its formula - CuSO4.5H2O

• Crystals of a substance which changed their colour on heating in a closed test tube but regained it after sometime when they were allowed to cool down are copper sulphate or more specifically hydrated copper sulphate.Its formula - CuSO4.5H2OThe phenomena involved is due to the presence of molecules of water of crystallization in the molecule. Water of crystallization is the fixed number of water molecules that are present in one formula unit of a salt. When we heat the crystals of hydrated copper sulphate this water is removed and the salt turns white. But when it is allowed to cool down in open air then it regains its lost water of crystallization and hence regains its colour also.

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