Identifying Gases for AQA A-level Chemistry

Identifying Gases

This page covers the following topics:

1. Test for hydrogen
2. Test for carbon dioxide
3. Test for oxygen
4. Test for chlorine
5. Gas tests

We can test for hydrogen by placing a lighted split in a test tube containing the gas.

Test for hydrogen

The test for carbon dioxide involves bubbling the gas through limewater.

Test for carbon dioxide

We can use a glowing splint to test for oxygen in a test tube.

Test for oxygen

We can use damp litmus paper to test for chlorine.

Test for chlorine

Gases can be identified in the lab by simple tests.

Gas tests

1

If oxygen is present in the test tube what will we see?

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The glowing splint will relight

If oxygen is present in the test tube what will we see?

2

What property of chlorine gas is it that allows it to act as a bleach?

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It is an acidic gas.

What property of chlorine gas is it that allows it to act as a bleach?

3

You suspect a gas you are testing to be toxic, what precaution should you take when testing it in the lab?

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Carry out the tests in a fume cupboard.

You suspect a gas you are testing to be toxic, what precaution should you take when testing it in the lab?

4

What type of paper is used in the test for chlorine?

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Damp litmus paper.

What type of paper is used in the test for chlorine?

5

You are testing a gas you know to be either hydrogen or chlorine. Which test would you use? Why?

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The test for hydrogen - it is quicker and easier to carry out.

You are testing a gas you know to be either hydrogen or chlorine. Which test would you use? Why?

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