Ferrous Sulfate (FeSO₄)

Preparation

• Ferrous sulfate can be prepared by:

  • Reacting iron metal with dilute sulfuric acid:

Fe + H2SO4 → FeSO4 + H2

• Reacting ferrous oxide with sulfuric acid:

FeO + H2SO4 → FeSO4 + H2O

• Reacting ferrous hydroxide with sulfuric acid:

Fe(OH)2 + H2SO4 → FeSO4 + 2H2O

Properties

• Physical Appearance: Greenish-white crystalline solid when hydrated (FeSO₄·7H₂O) and a white powder when anhydrous (FeSO₄).

• Solubility: Soluble in water, with a slightly acidic taste.

• Nature: Ionic compound.

• Melting Point: 70°C (158°F) for the heptahydrate form.

• Chemical Nature: Oxidizing agent, reactive with reducing agents.

Uses

1. Dietary Supplement: Used to treat iron-deficiency anemia.

2. Agriculture: Serves as a fertilizer to correct iron deficiencies in plants.

3. Water Treatment: Used for phosphate removal and as a coagulant.

4. Manufacturing: Employed in the production of inks, wood preservatives, and other chemicals.

Storage of Ferrous Sulfate

• Store in a cool, dry place, away from heat and direct sunlight.

• Keep in a tightly closed container to minimize exposure to air and moisture.

• Store away from strong oxidizing agents and reducing agents to prevent chemical reactions

Assay

• Method: Redox titration using potassium permanganate (KMnO₄).

Procedure:

1. Prepare a standard KMnO₄ solution of known concentration.

2. Weigh a sample of ferrous sulfate and dissolve it in distilled water, adding a small amount of sulfuric acid.

3. Heat the solution to 60-70°C to ensure a faster reaction.

4. Titrate the ferrous sulfate solution with the KMnO₄ solution.

5. The reaction forms ferric sulfate (Fe₂(SO₄)₃) and manganese(II) sulfate (MnSO₄).

6. Continue until a pale pink color persists, indicating the endpoint.

7. Calculate the concentration of ferrous sulfate using the volume of titrant and the concentration of KMnO₄.