A student performs a neutralisation reaction. They add a few drops of phenolphthalein indicator to dilute hydrochloric acid in a conical flask. Sodium hydroxide solution is then added slowly from a burette until the mixture has just turned alkali at the endpoint.
State the colour change of the phenolphthalein during this reaction.
276 exam-style questions on Edexcel GCSE Chemistry 4.1 Acids, covering 4.1.1 Acids, alkalis and the pH scale, 4.1.2 Hydrogen ion concentration and pH, 4.1.3 Dilute and concentrated, weak and strong acids, 4.1.4 Bases, alkalis and the reactions of acids, 4.1.5 Chemical tests for hydrogen and carbon dioxide, 4.1.6 Neutralisation as a reaction of acids with bases, 4.1.7 Preparing soluble salts, and 4.1.8 Solubility rules and preparing insoluble salts. Each one has a worked solution and a mark scheme showing where the marks go.