GCSE Chemistry Required Practical 7 | Tests for Ions (AQA)
Learn the GCSE Chemistry Required Practical 7 – Tests for ions (identifying unknown ionic compounds) in one clear video. This experiment uses flame tests and a set of simple chemical tests to work out which cations and anions are present in unknown salts. In this video, we will: Explain the aim: to use chemical tests to identify the ions in unknown single ionic compounds, covering the ions from flame tests through to sulfates in the AQA specification. Show how to carry out flame tests for metal cations (Li⁺, Na⁺, K⁺, Ca²⁺, Cu²⁺), including cleaning a nichrome wire loop, dipping it into the sample and recording flame colours (crimson, yellow, lilac, orange‑red, green). Demonstrate sodium hydroxide precipitate tests for metal cations (e.g. Al³⁺, Ca²⁺, Mg²⁺, Cu²⁺, Fe²⁺, Fe³⁺), showing the characteristic colours and the effect of adding excess NaOH where relevant. Show the test for ammonium ions (NH₄⁺) using sodium hydroxide, gentle heating, and damp red litmus turning blue in the presence of ammonia gas. Demonstrate tests for anions: Carbonate ions (CO₃²⁻) with dilute acid and limewater going cloudy from CO₂. Sulfate ions (SO₄²⁻) with dilute acid and barium chloride giving a white precipitate. Halide ions (Cl⁻, Br⁻, I⁻) with dilute nitric acid and silver nitrate, giving white, cream or yellow precipitates. Walk through how to organise results in a table and then use the pattern of observations to deduce the identity of unknown salts, with worked examples. Highlight safety and good practice: small quantities only, safe use of a Bunsen burner, wearing goggles, and careful labelling of all solutions. Practise exam‑style questions based on this required practical, including 6‑mark “describe the tests you would use to distinguish…” questions, with model answers using key phrases like “white precipitate”, “effervescence”, “turns limewater cloudy”, “flame test” and “Rf not required here”. ✅ Don’t forget to subscribe for more CK's GCSE & A-Level Hubs! #GCSEChemistry #AQA #RequiredPractical1 #Testsforions #GCSEScience #ChemistryRevision
