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ICSE Class 10 · Chemistry · Chapter 8

Study of Compounds – Hydrogen Chloride

3 topics · 20 questions

Smart summary

Everything you need, in order

Preparation of HCl

  • Laboratory Preparation: NaCl + H₂SO₄ → NaHSO₄ + HCl↑ (below 200°C). Heating common salt with conc. H₂SO₄.
  • Setup: Round bottom flask with delivery tube. NaCl is heated with conc. H₂SO₄. HCl gas collected by upward displacement of air (denser than air).

  • Drying: Passed through conc. H₂SO₄ (hygroscopic drying agent). Cannot use CaCl₂ (reacts with HCl).

    Why H₂SO₄: Non-volatile, less volatile than HCl, displaces HCl from chlorides.

    Industrial Preparation: Direct combination - H₂ + Cl₂ → 2HCl (in presence of sunlight).

    Laboratory preparation of hydrogen chloride gas using sodium chloride and concentrated sulfuric acid

Properties of HCl

  • Physical: Colorless, pungent-smelling gas. Heavier than air (M = 36.5). Highly soluble in water (1:500 ratio).
  • Fountain Experiment: Demonstrates high solubility. Water rushes into flask containing HCl creating fountain effect.
  • Acidic Nature: Dissolves in water to form hydrochloric acid. HCl → H⁺ + Cl⁻. Turns blue litmus red.
  • Chemical Properties: Reacts with NH₃ to form white fumes of NH₄Cl. HCl + NH₃ → NH₄Cl↓ (white fumes - test for HCl).
  • With Metals: Zn + 2HCl → ZnCl₂ + H₂↑. With Carbonates: CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂↑
  • Aqua Regia: HCl : HNO₃ in 3:1 ratio. Can dissolve noble metals like gold and platinum.

Tests and Uses

  • Test for HCl Gas: White fumes with NH₃. Glass rod dipped in NH₄OH held near HCl gives dense white fumes.
  • Test for Cl⁻ ions: AgNO₃ gives white precipitate of AgCl, soluble in NH₄OH. NaCl + AgNO₃ → AgCl↓ (white) + NaNO₃.
  • Uses: Manufacturing of aqua regia, cleaning metals (pickling), making chlorides, refining sugar, medicines.
  • Hydrochloric Acid: Aqueous solution of HCl. Strong mineral acid. Gastric juice contains dilute HCl (aids digestion).

Quiz

Test your knowledge

Multiple choice

  1. Question 1 of 19Knowledge
    HCl is prepared in lab by heating NaCl with:
  2. Question 2 of 19Knowledge
    HCl gas is dried using:
  3. Question 3 of 19Knowledge
    HCl gas is collected by:
  4. Question 4 of 19Knowledge
    The test for HCl gas is:
  5. Question 5 of 19Knowledge
    Aqua regia is a mixture of:
  6. Question 6 of 19Assertion-Reasoning
    Assertion (A): HCl cannot be dried using CaCl₂. Reason (R): CaCl₂ reacts with HCl.
  7. Question 7 of 19Knowledge
    The molecular mass of HCl is:
  8. Question 8 of 19Comprehension
    HCl is highly soluble in water because:
  9. Question 9 of 19Knowledge
    The fountain experiment demonstrates:
  10. Question 10 of 19Knowledge
    In industrial preparation, HCl is prepared by:
  11. Question 11 of 19Knowledge
    HCl gas turns moist blue litmus:
  12. Question 12 of 19Knowledge
    When HCl reacts with zinc, the gas evolved is:
  13. Question 13 of 19Knowledge
    The white precipitate formed when AgNO₃ reacts with HCl is:
  14. Question 14 of 19Knowledge
    Gastric juice in stomach contains:
  15. Question 15 of 19Comprehension
    HCl is collected by upward displacement of air because it is:
  16. Question 16 of 19Knowledge
    Which of the following is the correct laboratory preparation of HCl gas?
  17. Question 17 of 19Assertion-Reasoning
    Assertion (A): HCl gas is collected by upward displacement of air. Reason (R): HCl is lighter than air.
  18. Question 18 of 19Knowledge
    Which salt is formed when HCl reacts with ammonia?
  19. Question 19 of 19Knowledge
    What happens when HCl gas is passed through blue litmus paper?

Practice numericals

  1. Problem 1 of 1Application

0 of 20 answered