Iron Chemistry — Complete Bilingual Edition

1. Effect of Heat on Iron Compounds

Iron(II) Oxalate

(COO)₂Fe → FeO + CO₂ + CO

Iron(II) Oxalate → Iron(II) Oxide + Carbon Dioxide + Carbon Monoxide

Δ, absence of air

2FeO + ½O₂ → Fe₂O₃

Iron(II) Oxide + Oxygen → Iron(III) Oxide

Δ, presence of air

Iron(II) Carbonate (Siderite)

FeCO₃ → FeO + CO₂

Iron(II) Carbonate → Iron(II) Oxide + Carbon Dioxide

Δ, no air

2FeCO₃ + O₂ → Fe₂O₃ + 2CO₂

Iron(II) Carbonate + Oxygen → Iron(III) Oxide + Carbon Dioxide

Δ, presence of air

Limonite

2Fe₂O₃·3H₂O → 2Fe₂O₃ + 3H₂O

Hydrated Iron(III) Oxide → Iron(III) Oxide + Water

Δ, above 200°C

Iron(II) Sulphate

2FeSO₄ → Fe₂O₃ + SO₂ + SO₃

Iron(II) Sulphate → Iron(III) Oxide + Sulphur Dioxide + Sulphur Trioxide

Δ

Iron(III) Hydroxide

2Fe(OH)₃ → Fe₂O₃ + 3H₂O

Iron(III) Hydroxide → Iron(III) Oxide + Water

Δ, above 200°C

2. Reduction of Iron Oxides

A) Reduction by Carbon Monoxide

C₍s₎ + O₂₍g₎ → CO₂₍g₎

Carbon + Oxygen → Carbon Dioxide

Δ

2CO₂₍g₎ + C₍s₎ → 2CO₍g₎

Carbon Dioxide + Carbon → Carbon Monoxide

Δ

Fe₂O₃₍s₎ + 3CO₍g₎ → 2Fe₍s₎ + 3CO₂₍g₎

Iron(III) Oxide + Carbon Monoxide → Iron + Carbon Dioxide

Δ, above 700°C — blast furnace

B) Reduction by Water Gas (CO + H₂)

2CH₄₍g₎ + CO₂₍g₎ + H₂O₍v₎ → 3CO₍g₎ + 5H₂₍g₎

Methane + Carbon Dioxide + Water Vapor → Carbon Monoxide + Hydrogen

Δ

2Fe₂O₃₍s₎ + 3CO₍g₎ + 3H₂₍g₎ → 4Fe₍s₎ + 3CO₂₍g₎ + 3H₂O₍v₎

Iron(III) Oxide + Carbon Monoxide + Hydrogen → Iron + Carbon Dioxide + Water Vapor

Δ, Midrex furnace

3. Reactions of Iron

Combination & Oxidation

3Fe + 2O₂ → Fe₃O₄

Iron + Oxygen → Ferrosoferric Oxide

Δ

3Fe + 4H₂O → Fe₃O₄ + 4H₂

Iron + Water → Ferrosoferric Oxide + Hydrogen

At 500°C

2Fe + 3Cl₂ → 2FeCl₃

Iron + Chlorine → Iron(III) Chloride (oxidizing agent)

Δ

Fe + S → FeS

Iron + Sulphur → Iron(II) Sulphide (Fe is reducing agent)

Δ

Iron with Acids

Fe + 2HCl → FeCl₂ + H₂

Iron + Hydrochloric Acid → Iron(II) Chloride + Hydrogen

Dilute — Fe is reducing agent

Fe + HNO₃ → No reaction

Iron + Nitric Acid → No reaction (passivity)

Concentrated

Fe + H₂SO₄ → FeSO₄ + H₂

Iron + Sulphuric Acid → Iron(II) Sulphate + Hydrogen

Dilute — Fe is reducing agent

3Fe + 8H₂SO₄ → FeSO₄ + Fe₂(SO₄)₃ + 4SO₂ + 8H₂O

Iron + Sulphuric Acid → Iron(II) Sulphate + Iron(III) Sulphate + Sulphur Dioxide + Water

Concentrated, hot

4. Oxidation of Impurities (S, P)

Sulphur & Phosphorus

S₍s₎ + O₂₍g₎ → SO₂₍g₎

Sulphur + Oxygen → Sulphur Dioxide

Δ

4P₍s₎ + 5O₂₍g₎ → 2P₂O₅₍g₎

Phosphorus + Oxygen → Phosphorus Pentoxide

Δ

5. Acid Reactions of Iron Oxides

Iron(II) Oxide

FeO + H₂SO₄ → FeSO₄ + H₂O

Iron(II) Oxide + Sulphuric Acid → Iron(II) Sulphate + Water

Dilute

FeO + 2HCl → FeCl₂ + H₂O

Iron(II) Oxide + Hydrochloric Acid → Iron(II) Chloride + Water

Dilute

Iron(III) Oxide

Fe₂O₃ + 3H₂SO₄ → Fe₂(SO₄)₃ + 3H₂O

Iron(III) Oxide + Sulphuric Acid → Iron(III) Sulphate + Water

Concentrated

Fe₂O₃ + 6HCl → 2FeCl₃ + 3H₂O

Iron(III) Oxide + Hydrochloric Acid → Iron(III) Chloride + Water

Concentrated

Magnetite (Fe₃O₄)

Fe₃O₄ + 4H₂SO₄ → Fe₂(SO₄)₃ + FeSO₄ + 4H₂O

Ferrosoferric Oxide + Sulphuric Acid → Iron(III) Sulphate + Iron(II) Sulphate + Water

Concentrated

Fe₃O₄ + 8HCl → 2FeCl₃ + FeCl₂ + 4H₂O

Ferrosoferric Oxide + Hydrochloric Acid → Iron(III) Chloride + Iron(II) Chloride + Water

Concentrated

6. Partial Reduction / Interconversion of Iron Oxides

Using Hydrogen and Carbon Monoxide

Fe₂O₃₍s₎ + H₂₍g₎ → 2FeO₍s₎ + H₂O₍v₎

Iron(III) Oxide + Hydrogen → Iron(II) Oxide + Water Vapor

Δ, 400–700°C

Fe₃O₄₍s₎ + H₂₍g₎ → 3FeO₍s₎ + H₂O₍v₎

Ferrosoferric Oxide + Hydrogen → Iron(II) Oxide + Water Vapor

Δ, 400–700°C

Fe₃O₄₍s₎ + CO₍g₎ → 3FeO₍s₎ + CO₂₍g₎

Ferrosoferric Oxide + Carbon Monoxide → Iron(II) Oxide + Carbon Dioxide

Δ, 400–700°C

3Fe₂O₃₍s₎ + CO₍g₎ → 2Fe₃O₄₍s₎ + CO₂₍g₎

Iron(III) Oxide + Carbon Monoxide → Ferrosoferric Oxide + Carbon Dioxide

230–380°C

Oxidation of Magnetite

2Fe₃O₄₍s₎ + ½O₂₍g₎ → 3Fe₂O₃₍s₎

Ferrosoferric Oxide + Oxygen → Iron(III) Oxide

7. Preparation and Conversion Reactions

Iron(III) Hydroxide from Iron(III) Chloride

FeCl₃₍aq₎ + 3NH₄OH₍aq₎ → 3NH₄Cl₍aq₎ + Fe(OH)₃₍s₎

Iron(III) Chloride + Ammonium Hydroxide → Ammonium Chloride + Iron(III) Hydroxide

Fe(OH)₃ — reddish-brown precipitate

Three Iron Oxides from Iron

3Fe + 2O₂ → Fe₃O₄

Iron + Oxygen → Ferrosoferric Oxide

Fe₃O₄ + H₂ → 3FeO + H₂O

Ferrosoferric Oxide + Hydrogen → Iron(II) Oxide + Water

Δ, 400–700°C

2FeO + O₂ → Fe₂O₃

Iron(II) Oxide + Oxygen → Iron(III) Oxide

Iron(III) Oxide from Iron(III) Chloride

FeCl₃ + 3NH₄OH → 3NH₄Cl + Fe(OH)₃

Iron(III) Chloride + Ammonium Hydroxide → Ammonium Chloride + Iron(III) Hydroxide

2Fe(OH)₃ → Fe₂O₃ + 3H₂O

Iron(III) Hydroxide → Iron(III) Oxide + Water

Δ, above 200°C

Iron(II) Hydroxide from Iron(III) Hydroxide

2Fe(OH)₃ → Fe₂O₃ + 3H₂O

Iron(III) Hydroxide → Iron(III) Oxide + Water

Δ, above 200°C

Fe₂O₃ + H₂ → 2FeO + H₂O

Iron(III) Oxide + Hydrogen → Iron(II) Oxide + Water

Δ, 400–700°C

FeO + H₂SO₄ → FeSO₄ + H₂O

Iron(II) Oxide + Sulphuric Acid → Iron(II) Sulphate + Water

Dilute

FeSO₄ + 2NaOH → Na₂SO₄ + Fe(OH)₂

Iron(II) Sulphate + Sodium Hydroxide → Sodium Sulphate + Iron(II) Hydroxide

8. Role of Reducing Agents in Furnaces

A) Coke Coal in Blast Furnace

C + O₂ → CO₂

Carbon + Oxygen → Carbon Dioxide

Δ

2CO₂ + C → 2CO

Carbon Dioxide + Carbon → Carbon Monoxide

Role: producing CO

B) Natural Gas in Midrex Furnace

2CH₄ + CO₂ + H₂O → 3CO + 5H₂

Methane + Carbon Dioxide + Water → Carbon Monoxide + Hydrogen

Role: producing water gas

Iron Chemistry — Complete Edition

1. Effect of Heat on Iron Compounds

2. Reduction of Iron Oxides

3. Reactions of Iron

4. Oxidation of Impurities (S, P)

5. Acid Reactions of Iron Oxides

6. Partial Reduction / Interconversion of Iron Oxides

7. Preparation and Conversion Reactions

8. Role of Reducing Agents in Furnaces