Question

06. Give the
(i)Name and write formula of a salt that contains 7 molecules of water of crystallization
(ii) Name and formula of the compound formed by the reaction of calcium oxide and water ​

Answer 1

Answer:

(a) Gypsum (CaSO

4

.2H

2

O) contains two molecules of water of crystallisation.

(b) Copper sulphate crystals (CuSO

4

.5H

2

O) contains five molecules of water of crystallisation.

(c) Sodium carbonate crystal (Na

2

CO

3

.10H

2

O) contains ten molecules of water of crystallisation.

Answer 2

Explanation:

(i) Sodium Carbonate (Washing soda):

Sometimes, crystals of sodium carbonate contain seven water molecules. In such case chemical formula of sodium carbonate is written as Na2CO3 . 7 H2O and it is called sodium carbonate heptahydrate.

(ii) Calcium hydroxide, also called slaked lime, Ca(OH)2, is obtained by the action of water on calcium oxide.

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