Question

recognition and identification of gases​

Answer 1

Tests for gases

Hydrogen, oxygen, carbon dioxide, ammonia and chlorine can be identified using different tests.

Hydrogen

A lighted wooden splint makes a popping sound in a test tube of hydrogen.

Oxygen

A glowing wooden splint relights in a test tube of oxygen.

Carbon dioxide

Carbon dioxide turns limewater milky. A lighted wooden splint goes out in a test tube of carbon dioxide but this happens with other gases, too. So the limewater test is a better choice.

Ammonia

Ammonia has a characteristic sharp, choking smell. It also makes damp red litmus paper turn blue. Ammonia forms a white smoke of ammonium chloride when hydrogen chloride gas, from concentrated hydrochloric acid, is held near it.

Chlorine

Chlorine has a characteristic sharp, choking smell. It also makes damp blue litmus paper turn red, and then bleaches it white. Chlorine makes damp starch-iodide paper turn blue-black.