GCSE · Chemistry · AQA · Spec 8462

Test for hydrogen

You can't tell which gas is in a test tube just by looking. But hydrogen gives itself away: bring a flame to it and listen.

The test for hydrogen

Make the gas give itself away

View: 1. Flame at the open end. Showing 2 layers: Test tube and burning splint, Listen

View

Explore

tap a part, then try each view

The burning splint is at the open end of the tube. Now listen.

Tap each part of the test, then switch to the second view to see what hydrogen does.

Near misses

Which version of the test would you do?

Jas has a test tube of gas and wants to find out whether it is hydrogen. Jas has four ideas about how to do the test.

Which one is closest to what you would do right now?

Blow the flame out so the splint is just glowing, then hold it at the open end.Push the burning splint right down inside the tube, into the gas.Hold a burning splint at the open end of the tube and listen. A pop means hydrogen.If it pops, something went wrong. With hydrogen, the splint's flame would just get bigger.

How sure are you?

I'm sureI think soI'm guessing

Blow the flame out so the splint is just glowing, then hold it at the open end.

This is a common misconception

Nearly, but the splint is the wrong kind. The test uses a burning splint, one with a real flame on it. A glowing splint has only a red tip and no flame. Keep the flame on.

Push the burning splint right down inside the tube, into the gas.

This is a common misconception

Right splint, wrong place. The burning splint is held at the open end of the tube, at its mouth, not pushed down inside. Where you hold it is part of the test, so the position matters as much as the flame.

Hold a burning splint at the open end of the tube and listen. A pop means hydrogen.

This matches the evidence

That's the test. A burning splint, held at the open end, and a pop as the hydrogen burns rapidly. The pop is the positive result, so it is your evidence that the gas is hydrogen.

If it pops, something went wrong. With hydrogen, the splint's flame would just get bigger.

This is a common misconception

The pop isn't a mistake. It's the whole point. Hydrogen burns rapidly with a pop, and that pop is the positive result you are listening for. A bigger flame is not what this test looks for, so don't swap the pop for it.

Get all three right: which splint (burning), where (the open end), and what you're listening for (a pop).

Reading the result

What you heard, and what it lets you say

Choose what you hear, then follow it to what you are allowed to conclude.

What you hear

2 possible results.

On A burning splint is held at the open end of a test tube of the gas. 2 branches to choose from.

Watch out: No pop doesn't name the gas. It only tells you the test hasn't shown hydrogen.

Your turn to write it

Put the test into words

Describe the test for hydrogen. Give the result you would get if the gas is hydrogen. [2 marks]

Your answer

0 words · your answer stays on this page and is not sent anywhere.

The mark scheme

A burning (lit) splint is held at the open end of a test tube of the gas. A glowing splint does not get this point, because the test needs a flame. (1 mark)
There is a pop (the hydrogen burns rapidly with a pop). A bigger flame or a colour change does not get this point. (1 mark)

Model answer

Hold a burning splint at the open end of a test tube of the gas. If the gas is hydrogen, it burns rapidly with a pop.

Say which splint, say where it goes, and name the pop. Those are the words that carry the marks.

WHAT YOU'VE LEARNED

A quick recap of today's lesson.

One burning splint, one place to hold it, one sound to listen for.

What you need to know

The test for hydrogen uses a burning splint: a splint with a flame on it.
The burning splint is held at the open end of a test tube of the gas.
If the gas is hydrogen, it burns rapidly with a pop. The pop is the positive result.

The big picture

To test a gas for hydrogen, hold a burning splint at the open end of a test tube of the gas. If the gas is hydrogen, it burns rapidly with a pop. That pop is the positive result, and it is the evidence that the gas is hydrogen.

Key points

1Which splint? A burning one, with a flame. Not a glowing one.

2Where does it go? At the open end of the test tube, not pushed down inside.

3What do you listen for? A pop, as the hydrogen burns rapidly.

4What does the pop show? It is the positive result: the gas is hydrogen.

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Worked example

Problem

A student tests two test tubes of gas, X and Y. For X, the student holds a burning splint at the open end and hears a pop. For Y, the student pushes a burning splint right down to the bottom of the tube and hears nothing. What can the student conclude about each tube?

⚠ Watch out

Writing 'glowing splint' instead of 'burning splint', or leaving out where the splint goes. The test needs a burning splint held at the open end of the tube, and the result is a pop.

🧠

Memory hook

Hydrogen doesn't show itself, it tells you. Flame to the mouth, then listen for the pop.

✓

Check yourself

Cover the page and answer three quick questions out loud: which kind of splint, where you hold it, and what you hear if the gas is hydrogen.

Flashcards

(5)

What kind of splint is used in the test for hydrogen?

A burning splint: one with a flame on it.

Where is the splint held in the hydrogen test?

At the open end of the test tube of gas.

What do you hear if the gas is hydrogen?

A pop. That is the positive result.

What makes the pop in the hydrogen test?

The hydrogen burning rapidly.

In the hydrogen test, what does the pop tell you?

It is the positive result: the gas is hydrogen.

Tap any card to flip it, or use Study as deck to go through them one at a time. In the full lesson these run as a spaced-repetition deck — you rate each card Hard, Good or Easy and the tricky ones keep coming back until they stick.

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Which version of the test would you do?

What you heard, and what it lets you say

Put the test into words

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