Gas Tests Gauntlet

Four gases, four tests

Chemists need quick tests to tell common gases apart. There are four you must know exactly. Hydrogen makes a squeaky pop when a lit splint is held to it. Oxygen relights a glowing splint. Carbon dioxide turns limewater cloudy when bubbled through it. Chlorine bleaches damp litmus paper white. The key skill is to give both halves of each test: what you do, and what a positive result looks like. This module drills all four tests and their results.

Gas test words

Learn these words before you sort any test, because the exam expects the exact language. Each of the four gas tests has an action that you carry out and a result that you observe, and a full answer always gives both halves rather than just one.

Lit splint against glowing splint

The two splint tests are the ones learners mix up. The state of the splint tells them apart.

How to state a gas test

Always give two things: what you do and what you see. Name the action, such as holding a burning splint to the gas, lowering a glowing splint in, bubbling the gas through limewater, or holding damp litmus paper in it. Then state the result that confirms the gas, such as a pop, a splint relighting, a liquid turning cloudy, or the paper going white. Marks are lost when only the action is given, so pair every test with its result.

Match the gas to its test result

How do you test for oxygen?

Which test correctly identifies oxygen, with its result?

• A glowing splint lowered into the gas relights.
• A lit splint gives a squeaky pop.
• The gas turns limewater cloudy.
• The gas bleaches damp litmus paper white.

Correct gas tests

Select the TWO statements that give a gas test correctly, with its result.

• Carbon dioxide turns limewater cloudy
• Chlorine bleaches damp litmus paper white
• Hydrogen relights a glowing splint
• Oxygen gives a squeaky pop with a lit splint

Count the tests left

A student has 4 unknown gas samples to identify. So far they have correctly identified 1 of them. Subtract to find how many samples are still to be identified. What is the answer?

Order a gas test

Put the steps of carrying out a gas test in order, earliest first.

• Collect the unknown gas in a tube
• Prepare the test, such as lighting a splint
• Apply the test to the gas
• Observe and record the result

Complete the tests

A lit splint held to _____ gives a squeaky pop. A glowing splint relights in _____. When bubbled through limewater, _____ turns it cloudy. Damp litmus paper is bleached white by _____.

Match the observation to the gas

Spot the true gas test facts

Tap the TWO statements that describe a gas test correctly.

• Hydrogen gives a squeaky pop with a lit splint
• Carbon dioxide turns limewater cloudy
• Oxygen gives a squeaky pop with a lit splint
• Chlorine relights a glowing splint

Name the gas

Read each observation and choose the gas it identifies.

• A lit splint is held to a tube of gas and there is a loud squeaky pop. Which gas is it?
• A gas is bubbled through limewater and the clear liquid turns cloudy. Which gas is it?
• A piece of damp coloured litmus paper is held in a gas and quickly turns white. Which gas is it?

Explain the gas tests

Explain how you would test for hydrogen, oxygen, carbon dioxide and chlorine, giving both the test and its result for each.

• Explain the test for hydrogen and its result
• Explain the test for oxygen and its result
• Explain the test for carbon dioxide and its result
• Explain the test for chlorine and its result