In an investigation into the neutralisation of acids, a student added solid magnesium oxide, MgO\text{MgO}MgO, in 0.15 g portions to a beaker containing 60 cm3 of dilute nitric acid, HNO3\text{HNO}_3HNO3.
Explain why the mixture was stirred thoroughly after each addition of magnesium oxide before the pH was measured.
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.