Name: Reactions of Metal Carbonates with Acids
Uploaded: 2019-07-19
Duration: 4 min 6 s
Description: When substances like metals and liquids like acid react, it produces salt, water, and carbon dioxide. Here, in this video, it has been explained in detail wi...

Question

What are hydrated salts and what happens when they are heated? Give an experiment to show the effect of heat.

Accepted Answer

A hydrated salt is a crystalline salt molecule that is loosely attached to a certain number of water molecules. Examples: blue vitriol and washing soda are hydrated salts.

When the hydrated salts are heated at a definite temperature water molecules are removed easily from the crystals and anhydrous salt is left behind.

Experiment:

Copper sulphate crystals (blue in color) on strong heating in a dry test tube, over the flame of a burner, for some time, loses water of crystallisation and turns to a white powdery substance, anhydrous copper sulphate.

The tiny water droplets appear on the inner wall of the boiling tube due to the liberation of water molecules upon heating, which was present in hydrated copper sulphate.

The tiny water droplets appear on the inner wall of the boiling tube due to liberation of water molecules upon heating, which were present in hydrated copper sulphate.

${CuSO}_{4} . 5 H_{2} O (s) \overset{heat}{\to} {CuSO}_{4} (s) + H_{2} O$

On cooling the boiling tube the white powder is taken out on a glass. Now on adding few drops of water on this white powder, the original blue color of hydrated copper sulphate is restored due to the conversion to hydrated copper sulphate.

${CuSO}_{4} (s) + 5 H_{2} O \to {CuSO}_{4} . 5 H_{2} O (s)$

What are hydrated salts and what happens when they are heated? Give an experiment to show the effect of heat.

Important Questions on Acids, Bases and Salts

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