A student carries out a titration to determine the concentration of a sodium hydroxide solution. They pipette 25.0 cm3 of the sodium hydroxide solution into a conical flask and add a few drops of phenolphthalein indicator. Dilute hydrochloric acid is then added from a burette until the end point is reached.
Which of the following shows the colour change that is seen in the conical flask at the end point of this titration?
colourless to pink
pink to colourless
yellow to red
red to yellow
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.