Fiducia TogetherChemical analysis
Tests that identify what something is. Flame tests, gas tests and chromatography.
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.
What it is
Qualitative analysis identifies substances present. Gas tests, flame tests, precipitate tests and chromatography are the standard GCSE methods.
Where it applies
GCSE chemistry, with a required practical on chromatography.
How it works
The gas tests are fixed and must be memorised: hydrogen gives a squeaky pop with a lit splint; oxygen relights a glowing splint; carbon dioxide turns limewater milky; chlorine bleaches damp litmus paper.
Chromatography separates a mixture by how strongly components are attracted to the stationary and mobile phases; Rf is distance moved by the spot divided by distance moved by the solvent.
How to use it in your work
Learn the four gas tests exactly, with both the test and the positive result. Half an answer scores nothing.
For Rf, measure to the CENTRE of the spot and give the value with no units.
A pure substance gives one spot and melts at a sharp temperature; a mixture melts over a range.
Where to get help
Your teacher, your board's specification for the depth required at your tier, and Bitesize for the diagrams.
Revise this with a song
These are ours. We write revision songs because a lot of people remember a tune when they cannot remember a page, and because revising out loud in the kitchen beats staring at a highlighter.
- The Chemistry Song The GCSE chemistry specification, set to music.
Where to read more
Last reviewed 2026-08-28 by Fiducia Together · Next review due 2027-08-28
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.