Chemical Analysis and Tests

What the unit covers

This unit sits in the Chemical Analysis strand of Chemistry. Most of it is about identifying substances: ions, gases, water and organic compounds. The resources mention GCSE Chemistry, AQA GCSE Chemistry, IGCSE Chemistry and A-level Chemistry, and a smaller share goes further into instrumental methods.

Start with the ion tests

Begin with the mind map Chemical tests. It sets out flame test colours: yellow for Na+, crimson red for Li+, brick red for Ca2+, lilac for K+ and green or blue for Cu2+. Then open Testing for Positive and Negative Ions, which explains that heating a compound makes it glow a colour that depends on the metal ion.

Next, move to Anion Tests. It covers nitrate, iodide, chloride, carbonate and sulphate, including the sodium hydroxide and aluminium powder test that gives ammonia gas, which turns moist red litmus paper blue. The mind map Testing for ions adds the ammonium ion test.

Use quizzes and maps together

Read a map first, then test yourself. The quiz Anions test asks which anion is present when a white precipitate forms after dilute hydrochloric acid and barium nitrate. Cation, Anion & Flame Tests asks about a cream precipitate with silver nitrate. Check any wrong answers against the map, then retry the quiz.

• Map, then quiz, then flashcards.
• Use the OCR A-Level flowchart on testing for ions to practise the order of steps.
• Try Identification of Ions & Gases Quiz once ions feel secure.

Going further

Once the basic tests are familiar, look at the maps on Paper Chromatography, Spectroscopic techniques, GC-MS and HPLC. The HPLC map lists advantages such as sensitivity and automation. Flashcards such as Topic 8 - Chemical analysis cover pure substances, melting and boiling points, and formulations. A few resources suit university students too.

Make it yours

Teachers can set a map or quiz as a starter task. Students can pick one set above and write a few flashcards of their own for the tests they find hardest.