A student prepares a pure, dry sample of a soluble salt from an insoluble metal carbonate and a dilute acid.
Which change to the method would reduce the purity of the final crystals?
adding the carbonate in excess
filtering the mixture before crystallising
not filtering off the unreacted carbonate
leaving the crystals to dry in a warm place
40 exam-style questions on AQA GCSE Chemistry 4.2 Reactions of acids, covering 4.2.1a Reactions of acids with metals, 4.2.1b Redox in acid-metal reactions, 4.2.2 Neutralisation of acids and salt production, 4.2.3 Soluble salts, 4.2.4 The pH scale and neutralisation, 4.2.5a Titrations, 4.2.5b Calculating quantities in titrations, and 4.2.6 Strong and weak acids. Each one has a worked solution and a mark scheme showing where the marks go.