Water Of crystallisation

Question 1 What is meant by water of crystallisation?Give example?
Question 2 What are hydrated salts?
Question 3 What are anhydrous salts?
Question 4 Name a compound which contains two molecules of water of crystallisation?
Question 5 Why copper sulphate is blue in colour?
Water Of crystallisation
The water molecules which form part of the structure of a crystal are called water of crystallisation.
 The salts which contain water of crystallisation are called hydrated salts.
 For Ex:
1)Copper Sulphate crystals contain 5 molecules of water of crystallisation(CuSO4.5H2O)
It is blue in colour.
2)Sodium carbonate crystals contains 10 molecules of water of crystallisation(Na2CO3.10H2O)
3)Calcium sulphate crystals contains 2 molecules of water of crystallisation(CaSO4.2H20)
The water of crystallisation gives the crystals of the salts their shape and colour.
When hydrated salts are heated strongly,they lose their water of crystallisation.By losing water of crystallisation,the hydrated salts lose their regular shape and colour,and become colourless powdery substances,
The salts which have lost their water of crystallisation are called anhydrous salts.
For Ex:Copper sulphate crystals are blue in colour.When copper sulphate crystals are heated strongly,they lose water of crystallisation and form anhydrous copper sulphate which is white in colour.