Water of Crystallization

📚 Key Concepts

🔹 Real-Life Example

Have you noticed that blue copper sulphate crystals turn white when heated? This happens because the water molecules trapped in the crystal structure escape as steam. When you add water back to the white powder, it turns blue again! This trapped water is called water of crystallization.

Water of Crystallization: The fixed number of water molecules present in one formula unit of a salt, which is responsible for the shape and sometimes the colour of the crystals.

🧪 Important Examples

🔸 Common Hydrated Salts

🔸 Copper Sulphate Demonstration

Heating: CuSO₄·5H₂O → CuSO₄ + 5H₂O (Blue → White)

Adding Water: CuSO₄ + 5H₂O → CuSO₄·5H₂O (White → Blue)

🔍 Advanced: Importance

Water of crystallization helps maintain crystal structure and sometimes determines the physical properties like colour and shape of crystals.