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Activity 3.6 — Burning Sulphur: Acidic Oxide
NCERT Activity 3.6: Heat sulphur in a deflagrating spoon — it melts and burns with a pale blue flame producing SO₂. Dissolve the gas in water and test with litmus to confirm non-metal oxides are ACIDIC.
How To Perform
1
Add Sulphur to Spoon
Place yellow sulphur powder in the cup of a deflagrating spoon.
2
Heat Over Burner
Heat the spoon — sulphur melts (115°C) then burns with a PALE BLUE FLAME, producing SO₂ gas.
3
Dissolve SO₂ in Water
Collect the SO₂ gas and dissolve it in water to form H₂SO₃ (sulphurous acid).
4
Test with Litmus
Blue litmus turns RED — confirming the oxide is acidic.
5
Conclude
Non-metal oxides are acidic in nature. SO₂ is an acidic oxide.
⚠️ Safety Notes
- •SO₂ gas is pungent and suffocating — perform in a well-ventilated area or fume cupboard.
- •Do NOT inhale SO₂ directly — it irritates the respiratory system.
- •Wear safety goggles when heating sulphur.