Testing for Gases
Science: KS3, topic 2.8.1
Testing for Gases
In the Science lab different tests can be performed to identify different gases.
Hydrogen gas
- Hydrogen is an element with the symbol H
- It has an atomic mass of 1
- It contains 1 proton and 1 electron
- Hydrogen gas is flammable
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Testing for Hydrogen
- To test for Hydrogen gas we use the “squeaky pop” test
- This test requires you to put a lit splint near the top of a test tube containing hydrogen.
- The Hydrogen reacts with Oxygen and explodes – causing the squeaky pop.
- You can do after you react a metal such as magnesium with an acid in a test tube.
- If you put a boiling tube inverted over the top you can collect the hydrogen and complete the test.
Carbon dioxide gas
- Carbon Dioxide is a compound
- Carbon Dioxide has the formula CO2
- It has 1 atom of Carbon and 2 atoms of Oxygen
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Testing for Carbon Dioxide
- You can test for Carbon Dioxide by bubbling the gas through limewater.
- If Carbon Dioxide is present the limewater will turn from colourless to a cloudy milky colour.
- The chemical reaction here causes slaked lime to react with the carbon dioxide to form calcium carbonate.
- Reacting a metal carbonate with an acid produces a salt, water and carbon dioxide. By using a bung and delivery tube you can bubble the carbon dioxide gas through limewater.
Oxygen gas
- Oxygen is an element
- It has the symbol O
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Testing for Oxygen
- For the test for Oxygen take a glowing splint and if oxygen is present it will reignite.
Test yourself on Testing for Gases
How do you test for Carbon Dioxide?
Which gas is flammable?
A student lowers a glowing splint into a test tube of gas. The splint bursts back into flame. Which gas is in the tube?
Which statement correctly describes hydrogen, oxygen and carbon dioxide?