When Ferrous Sulphate (FeSO₄·7H₂O) is heated then it start losing water and form anhydrous ferrous sulphate (FeSO₄), which is further heated and forms Ferrous Sulphate (Fe₂O₃) , sulfur dioxide (SO₂) and sulfur trioxide (SO₃).

What is Ferrous Sulphate?

Ferrous Suphate is one of the most important compounds in chemistry. It is green in color and its chemical formula is FeSO₄·7H₂O. It has the common name green vitriol in chemistry.

What Happens When Ferrous Sulphate is Heated?

Heating of ferrous sulphate occurs in two stages.

Stage 1: Loss of Water of Crystallization

When ferrous sulphate crystals are heated slowly then it lose seven molecules of water.

Chemical Equation

FeSO4·7H2O ⟶(Heat) FeSO4 + 7H2O

Observation

• Green crystals of ferrous sulphate become white because 7 molecule of water is removed during heating.
• Water vapor is produced in this stage.

Stage 2: Thermal Decomposition takes place

On strong heating further, the white anhydrous ferrous sulphate start decompose.

Chemical Equation

2FeSO4 –Heat–> Fe2O3 + SO2 + SO3

Products Formed

Colour Change

Real-Life Applications of Ferrous Sulphate

Ferrous sulphate has wide use in laboratory and industries.

• it is used in manufacturing pigments
• In the laboratory it is used to making Iron supplements to treat anaemia
• it is used in Water treatment plants to purify it.
• it acts as a Fertilizers in soil
• Dyeing and textile industries used it for providing color to cloths.

Easy Trick to Remember

Green → White → Brown

• Green = FeSO₄·7H₂O
• White = FeSO₄
• Brown = Fe₂O₃

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