Give a chemical tests to identify hydrogen sulphide and carbon dioxide.
Test for hydrogen sulphide
The reaction with lead salts is the basis for the traditional test for hydrogen sulphide gas. Moist lead acetate (lead ethanoate) paper (see image, right) turns from white to silvery-grey or black when exposed to H2S.
Test for carbon dioxide
The most effective way to test for CO2 is to bubble the gas through "limewater", a diluted solution of calcium hydroxide (slaked lime). When you bubble carbon dioxide through the solution, it forms a solid precipitate of calcium carbonate – chalk or limestone.