A student standardises a solution of sodium hydroxide by adding it from a burette into a conical flask containing dilute hydrochloric acid and a few drops of indicator.
Which of the following correctly describes the indicator and the colour change observed in the conical flask at the end point of this titration?
Phenolphthalein | Pink to colourless
Methyl orange | Yellow to red
Phenolphthalein | Colourless to pink
Methyl orange | Red to blue
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.