Practical: Tests for gases

What is the method to test for hydrogen?

Collect hydrogen in a test tube, then bring a lit splint near the mouth of the test tube. Hydrogen gas will produce a "pop" sound if present.

How do you test for oxygen?

Collect oxygen in a test tube and insert a glowing splint. If oxygen is present, the splint will relight.

How do you test for carbon dioxide?

Collect carbon dioxide in a test tube and bubble it through limewater. The limewater will turn milky if carbon dioxide is present.

How do you test for chlorine gas?

Collect chlorine in a test tube and insert damp litmus paper. Chlorine will bleach the litmus paper and turn it white.

Why is it important to collect gas in a test tube for these tests?

To safely contain the gas and direct it towards the test equipment (splint, litmus paper).

How can you confirm the presence of ammonia gas?

Ammonia turns red litmus paper blue.

What does the "pop" sound indicate in the hydrogen test?

The "pop" sound indicates the presence of hydrogen gas, which reacts with oxygen to produce water and energy.

Why does limewater turn milky when carbon dioxide is bubbled through it?

Carbon dioxide reacts with calcium hydroxide in limewater to form calcium carbonate, which is insoluble and forms a white precipitate.

What happens to litmus paper when exposed to chlorine gas?

Chlorine bleaches the litmus paper, causing it to turn white.

Why is it important to use damp litmus paper for the chlorine test?

Damp litmus paper reacts more effectively with chlorine gas, allowing for a clearer result.

What color does litmus paper turn when exposed to ammonia gas?

Litmus paper turns blue when exposed to ammonia gas.

How would you test for the presence of sulfur dioxide?

Pass the gas through potassium dichromate solution; the solution will turn from orange to green if sulfur dioxide is present.

How do you safely collect gases during these tests?

Use a test tube or gas syringe to collect the gas, ensuring the gas does not escape or cause hazards.

How would you perform the chlorine test in a closed system?

You could use a sealed container with damp litmus paper inside, allowing chlorine to interact with the paper.

What precautions should be taken when testing for chlorine?

Perform the test in a well-ventilated area or under a fume hood, as chlorine gas is toxic.