Test for hydrogen — AQA GCSE Chemistry
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Test for hydrogen explained
Hydrogen is identified by its reaction with a lit splint.
Read the full explanation
Collect the gas in a test tube, then bring a burning splint to the open mouth of the tube. Hydrogen reacts rapidly with oxygen in the air, and the sudden combustion produces a sharp pop. The method matters: the splint must be at the open end, not pushed inside, and the tube should hold the gas rather than air. A squeaky pop confirms hydrogen; a glowing splint relighting would indicate oxygen instead. The test is quick and needs only a lit splint, but a very small amount of gas may give a faint pop, so collect enough gas and keep the tube mouth close to the flame.
Your focus
- Describe the test for hydrogen using a burning splint at the open end of a test tube.
- State the positive observation as a pop sound.
- Explain why hydrogen produces a pop when ignited in air.
Test for hydrogen exam tips
Marking Points
- State that a burning splint is held at the open end of a test tube containing the gas.
- Describe the positive result as a pop sound caused by rapid burning of hydrogen.
- Explain that hydrogen burns rapidly because it reacts with oxygen, releasing energy as sound and heat.
- Distinguish this test from the oxygen test, where a glowing splint relights rather than a burning splint popping.
- Note that the splint is not inserted into the tube; it is held at the open end so the gas ignites at the mouth.
Examiner Tips
- 💡Name both the splint type and its position: burning splint at the open end of the test tube.
- 💡Give the observation precisely as a pop sound, not just 'it burns'.
- 💡If asked to compare tests, contrast the burning splint for hydrogen with the glowing splint for oxygen in one sentence.
Common Mistakes
- Saying a glowing splint is used for hydrogen; the correct test uses a burning splint, while a glowing splint tests for oxygen.
- Pushing the burning splint deep into the test tube; the correct method holds it at the open end so the gas ignites safely at the mouth.
- Describing the result as a bang or explosion; the correct observation is a pop sound from rapid burning of a small volume of gas.