GCSE CHEMISTRY - What is the Test for Sulfur Dioxide Gas? - How do I test for Sulfur Dioxide Gas? - How is Sulfur Dioxide Gas Collected?

Test for Sulfur Dioxide Gas, SO₂_(g).

1) Sulfur dioxide gas has no colour.

2) Sulfur dioxide gas smells like burnt matches.

3) Sulfur dioxide gas turns moist litmus paper from blue to red
and moist universal indicator paper to red - it is acidic.

4) Sulfur dioxide gas will put out a lit splint.

Specific test.

Sulfur dioxide gas turns acidified
potassium dichromate(VI) solution from orange to green.
Chromium is reduced from (VI) to (III).

potassium sulfur sulfuric chromium(III) potassium
dichromate(VI) + dioxide + acid sulfate + sulfate + water.

K₂Cr₂O₇_(aq) + 3SO_2(g) + H₂SO₄_(aq) Cr₂(SO₄)₃_(aq) + K₂SO₄_(aq) + H₂O_(l)

Collecting Sulfur Dioxide Gas.

Sulfur dioxide gas is more dense than air and can
be collected by downward delivery or using a gas syringe.