Question

What happens when SO₂ gas is passed through a potassium dichromate solution?

• A. Colour changes from orange to green
• B. Colour changes from orange to red
• C. Colour changes from red to orange
• D. Colour changes from red to violet

Answer 1

The correct option is A

Colour changes from orange to green

When SO₂ gas is passed through potassium dichromate solution, the colour of potassium dichromate changes from orange to green (chromium sulphate). This is the potassium dichromate test for sulphuric acid.

2 K₂Cr₂O₇ + 8H₂SO₄ → 2 K₂SO₄ + 2 Cr₂(SO₄)₃ + 8 H₂O + 3O₂