Chemistry: Sulphuric Acid Overview

Sulphuric Acid

• Sulphuric acid is a strong acid, a powerful oxidizing agent, and a dehydrating agent, known as the "King of Chemicals."
• Its molecular formula is H₂SO₄ with a relative molecular mass of 98.
• It's produced by the contact process.
• Occurs naturally in certain mineral springs and in combined forms like Barytes (BaSO₄), Gypsum (CaSO₄·2H₂O), and Kieserite (MgSO₄·H₂O).

Preparation of Sulphuric Acid

• Can be prepared by the oxidation of sulfur dioxide using oxygen, chlorine, or bromine.
• Sulphur reacts with concentrated nitric acid.
• A method for producing sulphuric acid is via dissolving sulphuryl chloride in water.

Manufacture of Sulphuric Acid (Contact Process)

• The contact process for manufacturing sulfuric acid involves roasting metallic sulfides (e.g., 4FeS₂ + 11O₂ → 2Fe₂O₃ + 8SO₂) to produce sulfur dioxide.
• The sulfur dioxide is purified to remove impurities.
• Next, the purified sulfur dioxide is catalytically oxidized to sulfur trioxide using a catalyst like vanadium pentoxide (V₂O₅) at a temperature of about 450°C. (2SO₂ + O₂ → 2SO₃)
• The sulfur trioxide is absorbed in concentrated sulfuric acid (H₂SO₄) to form oleum (H₂S₂O₇). Oleum is then diluted with water to produce more sulfuric acid. (SO₃ + H₂SO₄ → H₂S₂O₇). (H₂S₂O₇ + H₂O → 2H₂SO₄)

Favourable Conditions for SO₂ Conversion to SO₃

• Low temperatures (around 410-450°C)
• Moderate pressure (1-2 atmospheres)
• Presence of a catalyst (platinum or vanadium pentoxide)

Physical Properties of Sulphuric Acid

• Colourless liquid
• Odourless
• Sour taste
• Dense & oily liquid
• High boiling point (338°C)
• High density (1.85 g/cc for pure H₂SO₄)
• Poor electrical conductor (except when dilute)
• Highly soluble in water
• Very corrosive
• Reacts with many substances

Chemical Properties of Dilute Sulfuric Acid

• Acidic properties: Dilute sulfuric acid reacts with metals above hydrogen in the reactivity series (e.g., Zn, Mg, Fe) forming metallic sulfates and hydrogen gas.
• Neutralisation: Dilute sulfuric acid neutralizes bases and alkali hydroxides, producing corresponding salts and water.
• Carbonate Reaction: Reacts with metal carbonates or bicarbonates releasing carbon dioxide (CO₂), and a salt.

Chemical Properties of Concentrated Sulfuric Acid

• Non-volatile nature: Has a high boiling point and is therefore, considered non-volatile.
• Dehydrating agent: Concentrated sulfuric acid readily removes water molecules from other substances.
• Oxidizing agent: Concentrated sulfuric acid can readily oxidize other substances (metals, non-metals).
• Other reactions: Reacts with metal sulphides, bisulphites, and other substances.

Uses of Sulphuric Acid

• Fertilizers (ammonium sulfate)
• Dyes and drugs
• Explosives (TNT)
• Acids (nitric, nitric, etc.)
• Oil refining
• Metallurgical processes

Explore the fascinating world of sulphuric acid, often referred to as the 'King of Chemicals.' This quiz covers its properties, preparation methods, and the contact process for its manufacture. Test your knowledge and deepen your understanding of this essential chemical!