What is Ferrous sulphate?

What is Ferrous sulphate?

Ferrous sulphate is salt of iron also known as Ferrous sulphate (Green vitriol), It is commonly known as hara Kasis.

The formula of Ferrous sulphate

The formula of ferrous sulphate is

Ferrous sulphate (Green vitriol), FeSO4.7H2O

Also Check: Baking Soda | Epsom salt | Glucose | Amino Acids

Related Links: Periodic Table Element | Metal | Electogravity

Preparation of Ferrous sulphate

1. By dissolving scrap Fe in dil. H2SO4
2. From Kipp’s waste which contains ferrous sulphate with some free H2SO4, the latter is neutralised with scrap iron forming FeSO4 and hydrogen.
3. By the action of air and water on iron pyrites. The solution is treated with scrap iron to remove H2SO4 and to reduce Fe³⁺ sulphate Fe²⁺ sulphate.

Properties of Ferrous sulphate

1. Hydrated and anhydrous FeSO4 are green and white in colour respectively. It is isomorphous with epsom salt, MgSO4.7H2O and ZnSO4.7H2O. It effervesces on exposure to air.
2. Light green crystals of FeSO4 lose water and turn brown on exposure to air, due to oxidation.
3. On heating at 300C it gives anhydrous FeSO4 which on further heating gives Fe2O3 and SO2.
4. Like other ferrous salts, it takes up HNO3 forming brown coloured double compound, Fe(NO)SO4, nitroso ferrous sulphate (Ring test for nitrates).
5. It decolourises acidified potassium permanganate and turns acidified dichromate green (reducing character).
6. It forms double salts with sulphates of alkali metals with general formula R2SO4.FeSO4.6H2O. With ammonium sulphate, it forms a double salt known as ferrous ammonium sulphate or Mohr’s salt, FeSO₄.(NH₄)₂SO₄.6H₂O. It does not effervesce. It ionises in solution to gives Fe 2+, NH 4+ and SO_{4 2-} ions.