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ICSE Class 10 · Chemistry · Chapter 10

Study of Compounds – Sulphuric Acid

5 topics · 15 questions

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Contact Process - Industrial Preparation

  • Contact Process: Industrial method to manufacture H₂SO₄. Three main steps.
  • Step 1 - SO₂ Formation: Burning sulphur or roasting metal sulphides. S + O₂ → SO₂ or 4FeS₂ + 11O₂ → 2Fe₂O₃ + 8SO₂.
  • Step 2 - SO₃ Formation: 2SO₂ + O₂ ⇌ 2SO₃ (V₂O₅ catalyst, 450°C, 1-2 atm). Reversible, exothermic reaction.
  • Step 3 - Oleum Formation: SO₃ dissolved in conc. H₂SO₄ to form oleum (H₂S₂O₇). SO₃ + H₂SO₄ → H₂S₂O₇.
  • Final Step: Oleum diluted with water. H₂S₂O₇ + H₂O → 2H₂SO₄.
  • Industrial preparation of sulfuric acid using the Contact process with vanadium pentoxide catalyst
  • Why Not Direct: SO₃ + H₂O → H₂SO₄ forms mist which is difficult to condense. Oleum method prevents this.

Properties of Sulphuric Acid

  • Physical Properties: Colorless, dense, oily liquid. Boiling point: 338°C. Miscible with water (highly exothermic).
  • Dilution: Always add acid to water, NEVER water to acid. Highly exothermic - water may boil and splash.
  • Hygroscopic: Absorbs moisture from air without dissolving. Used as drying agent.
  • Dehydrating Agent: Removes water from compounds. C₁₂H₂₂O₁₁ + H₂SO₄ → 12C (black) + 11H₂O (charring of sugar).
  • Acidic Properties: Strong dibasic acid. H₂SO₄ → 2H⁺ + SO₄²⁻. Neutralizes bases, reacts with metals, carbonates.
  • With Metals: Dilute acid: Zn + H₂SO₄ → ZnSO₄ + H₂↑. Conc. acid: Cu + 2H₂SO₄ (conc) → CuSO₄ + SO₂↑ + 2H₂O.

Special Properties and Reactions

  • Oxidizing Agent: Hot concentrated H₂SO₄ acts as oxidizing agent. H₂SO₄ → H₂O + SO₂ + [O].
  • With Non-metals: C + 2H₂SO₄ (conc) → CO₂ + 2SO₂ + 2H₂O. S + 2H₂SO₄ (conc) → 3SO₂ + 2H₂O.
  • With HX Acids: Displaces volatile acids. NaCl + H₂SO₄ → NaHSO₄ + HCl↑ (used to prepare HCl, HNO₃).
  • With Salts: Forms sulphates. CaCO₃ + H₂SO₄ → CaSO₄ + H₂O + CO₂↑.
  • Test for SO₄²⁻ ions: BaCl₂ + H₂SO₄ → BaSO₄↓ (white precipitate, insoluble in dil. HNO₃). Confirmatory test for sulphates.
  • Concentrated vs Dilute: Dilute - typical acid properties (H₂ with metals). Concentrated - oxidizing, dehydrating properties.

Uses of Sulphuric Acid

  • Fertilizers: Manufacturing ammonium sulphate (NH₄)₂SO₄, superphosphate Ca(H₂PO₄)₂.
  • Petroleum Refining: Removing impurities from petroleum products.
  • Lead-Acid Battery: Electrolyte in car batteries (dilute H₂SO₄).
  • Manufacturing: Paints, pigments, dyes, detergents, plastics, explosives.
  • Chemical Industry: Making other acids (HCl, HNO₃), salts, cleaning agents.
  • Laboratory Reagent: Drying gases, catalyst, pH adjustment.
  • Called 'King of Chemicals': Most important industrial chemical due to wide applications.

Important Reactions Summary

  • Dilute H₂SO₄ + Metal: Zn + H₂SO₄ (dil) → ZnSO₄ + H₂↑ (hydrogen evolution).
  • Conc. H₂SO₄ + Cu: Cu + 2H₂SO₄ (conc) → CuSO₄ + SO₂↑ + 2H₂O (SO₂ gas, acts as oxidizing agent).
  • With Carbonate: Na₂CO₃ + H₂SO₄ → Na₂SO₄ + H₂O + CO₂↑ (effervescence).
  • With Base: 2NaOH + H₂SO₄ → Na₂SO₄ + 2H₂O (neutralization).
  • Dehydration: CuSO₄·5H₂O + conc. H₂SO₄ → CuSO₄ (anhydrous) + 5H₂O (removes water of crystallization).
  • Safety: Handle with care - corrosive, causes severe burns. Neutralize spills with sodium bicarbonate.

Quiz

Test your knowledge

Multiple choice

  1. Question 1 of 15Knowledge
    The catalyst used in Contact process is:
  2. Question 2 of 15Knowledge
    While diluting concentrated sulphuric acid:
  3. Question 3 of 15Knowledge
    Concentrated H₂SO₄ is used as a drying agent because it is:
  4. Question 4 of 15Comprehension
    When conc. H₂SO₄ is added to sugar, it turns black because:
  5. Question 5 of 15Knowledge
    The basicity of H₂SO₄ is:
  6. Question 6 of 15Knowledge
    The test for sulphate ions involves:
  7. Question 7 of 15Knowledge
    When dilute H₂SO₄ reacts with zinc, the gas evolved is:
  8. Question 8 of 15Knowledge
    When concentrated H₂SO₄ reacts with copper, the gas evolved is:
  9. Question 9 of 15Assertion-Reasoning
    Assertion (A): H₂SO₄ is called 'King of Chemicals'. Reason (R): It has many industrial applications.
  10. Question 10 of 15Knowledge
    In Contact process, SO₃ is dissolved in conc. H₂SO₄ to form:
  11. Question 11 of 15Knowledge
    H₂SO₄ is used in lead-acid battery as:
  12. Question 12 of 15Application
    The molecular mass of H₂SO₄ is:
  13. Question 13 of 15Comprehension
    Concentrated H₂SO₄ cannot be used to dry:
  14. Question 14 of 15Knowledge
    In Contact process, the optimum temperature for SO₃ formation is:
  15. Question 15 of 15Application
    Which gas is produced when NaCl reacts with conc. H₂SO₄?

0 of 15 answered