Crystals of copper sulphate contain water of crystallization

Our Objective

To show that crystals of copper sulphate contain water of crystallization.


   The Theory

Crystallisation is a purification process that is used to separate solids from liquids. The most common way for filtering saltwater is this. A few water molecules are a crucial component of the crystal structure of certain salts. The water molecules that build up a crystal's structure are referred to as the water of crystallization. Salts that include the water that induces crystallization are known as hydrated salts.

The water of crystallization

A set number of molecules in one formula of a unit of salt is referred to as crystallization water. Hydrates are crystal salts that include water throughout the crystallization process. Water crystallization is also known as crystallization water or hydration water. Heat has a strong effect on these crystals.

Examples of water of crystallization are Washing soda, Gypsum, Proteins with more than 50% water of crystallization and copper sulphate pentahydrate with five molecules of water of crystallization are examples of water of crystallization. Hydrated Copper sulphate is represented as CuSO4.5H2O It means 5 molecules of water is associated each other.

Blue crystals of copper sulphate contains water of crystallization. These crystals dehydrate on heating to lose water of crystallization at a particular temperature and also change their colour.

CuSO4.5H2O(Blue) →CuSO4.H2O(Bluish white) →CuSO4 (White)

If the dehydrated copper sulphate solid material is allowed to cool in air, then it regains blue colour after gaining water molecules from the atmosphere.

CuSO4 + 5H2O → CuSO4.5H2O


Learning outcomes

  • Students understand the term “ Crystallisation” through the experiment. 
  • Students will be able to understand the changes occur during the process of Crystallisation.