test for gases

experiments to test for gases

Tests for gases

There are several different tests to detect and identify gases and the ions in compounds. It is important that the test for any gas or ion is unique. The results of a test must let you determine which gas or ion is present, rather being uncertain about which one it is.

Oxygen

Oxygen supports combustion. If oxygen is present in a test tube, a glowing splint relights when it is held inside.

Hydrogen

Hydrogen ignites in air. If hydrogen is present in a test tube, a lighted splint held near its mouth ignites with a squeaky pop.

Carbon dioxide

Carbon dioxide reacts with calcium hydroxide solution to produce a white precipitate of calcium carbonate. Limewater is a solution of calcium hydroxide. If carbon dioxide is bubbled through limewater, the limewater turns milky or cloudy white.

Chlorine

Chlorine is an acidic gas that also acts as a bleach. Damp litmus paper is bleached white when it is placed in chlorine.

If damp blue litmus paper is used, the paper turns red then white.

Summary