Ferrous Sulphate

 H A E M A t I N I C s

• Ferrous Sulphate (FeSO₄.7H₂O)
• molecular weight = 278
• Not less than 98% not more than 103.3 N 

PREPARATIONS

• It is obtained by dissolving iron in excess of dil. H₂SO₄
• After the effervescence stops ---> liquid is filtered, concentrated and cooled.
• The green crystals are formed 
• In all this operations undue exposure to air is prevented, because ferrous sulphate is oxidized readily on exposure to moist air and the crystal gets coated with brownish yellow ferric sulphate.

Fe + H₂SO₄ ------> FeSO₄ + H₂ ↑

PROPERTIES

• Occurs in green crystals or crystalline powders,
• Astringent taste,
• Effloresces in dry air,
• In air, oxidised to ferric salt of brownish yellow color,
• Soluble in water,
• Insoluble in alcohol,
• When heated, decomposes to yield Ferric Oxide, Sulphur dioxide, and sulphuric acid.

2(FeSO₄.7H₂O) + Heat -------> Fe₂O₃ + SO₂ + H₂SO₄ + 13H₂O

• Ferrous sulphate reduces the salts of silver and gold to their corresponding metals. with some alkali sulphates, it forms double salts.

Ag+ + Fe²⁺ ------> Ag + Fe³⁺

Au³⁺ + 3Fe²⁺ ------> Au + 3Fe³⁺

• In presence of light, it reduces mercuric chloride to mercurous chloride.

2HgCl₂ + 2Fe²⁺ ------> Hg₂Cl₂ + 3Fe³⁺ + 2Cl¯

• When it reacts with Sodium carbonate solution, CO₂ is evolved.

FeSO₄ + Na₂CO₃ ------> FeCO₃ + Na₂SO₄

FeCO₃ + 2H₂O ------> Fe(OH)₂ + CO₂

ASSAY

i) It is assayed by oxidation-Reduction type of  reaction using N/10 potassium permanganate solution in presence of dil. H₂SO₄.

Accurately weighed 1g is dissolved in 20ml of dil. H₂SO₄. Then it is titrated with N/10 KMnO₄.

2FeSO₄ + 2KMnO₄ + 4H₂SO₄ -------> K₂SO₄ + 2MnSO₄ + Fe₂H(SO₄)₃ + 4H₂O

Each ml of N/10 KMnO₄ = 0.0291g of FeSO₄.7H₂O.

ii) Now it is assayed by taking 1g of accurately weighed sample, dissolved in 30ml of water and 20ml of dil. H₂SO₄ in a flask and finally titrate it with 0.1M Cerric ammonium nitrate, using ferroin sulphate solution as an indicator. At the end point the red color gets changed to light blue.

2FeSO₄ + 2Ce(SO₄)₂ . 2(NH₄)₂SO₄ -------> Fe₂(SO₄)₃ + Ce₂(SO₄)₃ + 2MnSO₄ + (NH₄)₂SO₄

Each ml of 0.1M Cerric ammonium nitrate  = 0.0278g of FeSO₄.7H₂O.

Uses:

• Haematinic

storage:

• It should be stored in a tightly closed container.

Dose:

• 60 to 200mg.