How many molecules of water of crystallization (per formula unit) are present in:
(a) copper sulfate crystals?
(b) washing soda?
(c) gypsum?

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Solution

(a) Copper sulfate crystals $(C u S O_{4} . 5 H_{2} O)$ contain five molecules of water of crystallization.

(b) Sodium carbonate crystal or washing soda $(N a_{2} C O_{3} . 10 H_{2} O)$ contains ten molecules of water of crystallization.

(c) Gypsum $(C a S O_{4} . 2 H_{2} O)$ contains two molecules of water of crystallization.

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Q. How many molecules of water of crystallisation (per formula unit) are present in:
(a) copper sulphate crystals?
(b) washing soda?
(c) gypsum?

Water of crystallization is the fixed number of water molecules present in the crystal of that salt. The chemical formula of hydrated copper sulphate is CuSO₄.5H₂O i.e., there are five water molecules present in one formula unit of copper sulphate. Therefore, water of crystallization of copper sulphate is 5.

Similarly, there are two water molecules present in one formula unit of gypsum (CaSO₄.2H₂O). Hence, water of crystallization of gypsum is 2.

however in hemihydrated Caso4 is known as POP it has half water of crystalization. Pl explain

Q. How many molecules of water are present in one formula unit of copper sulphate pentahydrate?

The number of molecules of water of crystallization present in washing soda are:

Q. Copper sulphate crystals which seem to be dry contain water of crystallization. When we heat the crystals, this water is removed and the salt turns white. If you moisten the crystals again with water, you will find that blue colour of the crystals reappears.

The water of crystallization is the fixed number of water molecules present in one formula unit of a salt. Five water molecules are present in one formula unit of copper sulphate. The chemical formula for hydrated copper sulphate is

C u {S O}_{4}

5 H_{2} O

. Now you would be able to answer the question whether the molecule of

{N a}_{2} {C O}_{3}

10 H_{2} O

is wet. One other salt, which possesses water of crystallization is gypsum. It has two water molecules as a water of crystallization. It has the formula

C a {S O}_{4}

2 H_{2} O

What are the uses of this salt?

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How many molecules of water of crystallization (per formula unit) are present in:(a) copper sulfate crystals?(b) washing soda?(c) gypsum?

(a) Copper sulfate crystals (CuSO4.5H2O) contain five molecules of water of crystallization.(b) Sodium carbonate crystal or washing soda (Na2CO3.10H2O) contains ten molecules of water of crystallization.(c) Gypsum (CaSO4.2H2O) contains two molecules of water of crystallization.

How many molecules of water of crystallization (per formula unit) are present in:
(a) copper sulfate crystals?
(b) washing soda?
(c) gypsum?