Bitesize has changed! We're updating subjects as fast as we can. Visit our new site to find Bitesize guides and clips - and tell us what you think!
Print

Science

Preparing gases and testing for them

Page:

  1. 1
  2. 2
  3. 3
  4. 4
  1. Back
  2. Next

Testing for different gases

You need to know how to test for hydrogen, oxygen, carbon dioxide, ammonia and chlorine.

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

A lighted wooden splint goes out in a test tube of carbon dioxide but this happens with other gases, too. It is better to bubble the test gas through limewater - calcium hydroxide solution. Carbon dioxide turns limewater cloudy white.

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.

Page:

  1. 1
  2. 2
  3. 3
  4. 4
  1. Back
  2. Next

Back to Making changes index

BBC © 2014 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.