Which of the following are the constituents of a soda acid fire extinguisher?

General Science ·Previously asked in BPSC CCE 2024

View the full solved paper: GS 2024 (Series G)

Question

Which of the following are the constituents of a soda acid fire extinguisher?

  1. A. Conc. sulphuric acid and aluminium sulphate
  2. B. Dil. sulphuric acid and sodium carbonate
  3. C. Dil. sulphuric acid and sodium bicarbonate solution (Correct answer)
  4. D. Conc. sulphuric acid and sodium carbonate solution

Correct Answer

Option C — Dil. sulphuric acid and sodium bicarbonate solution

Detailed Solution & Explanation

The correct answer is Dil. sulphuric acid and sodium bicarbonate solution.

Key Points

  • A soda-acid fire extinguisher contains a solution of sodium bicarbonate (NaHCO₃) together with a small bottle of dilute sulphuric acid (H₂SO₄).
  • When the extinguisher is operated, the acid mixes with the sodium bicarbonate solution and they react to release a large amount of carbon dioxide (CO₂) gas.
  • The reaction is: 2NaHCO₃ + H₂SO₄ → Na₂SO₄ + 2H₂O + 2CO₂.
  • The CO₂ produced builds up pressure that expels the water, and the CO₂ blanket smothers the fire by cutting off oxygen.

Additional Information

  • it is used only for ordinary combustible (Class A) fires, not for electrical or oil fires — and the correct constituents are dilute sulphuric acid and sodium bicarbonate solution, option (C).