A student electrolyses aqueous potassium nitrate using inert electrodes. The solution contains potassium ions, nitrate ions, hydrogen ions and hydroxide ions. Hydrogen gas forms at the negative electrode.
Explain why hydrogen, rather than potassium, forms at the negative electrode. State whether the reaction at this electrode is oxidation or reduction.
76 exam-style questions on AQA GCSE Chemistry 4.3 Electrolysis, covering 4.3.1a The process of electrolysis, 4.3.1b Half equations in electrolysis, 4.3.2 Electrolysis of molten ionic compounds, 4.3.3 Using electrolysis to extract metals, 4.3.4 Electrolysis of aqueous solutions, and 4.3.5 Representation of reactions at electrodes as half equations. Each one has a worked solution and a mark scheme showing where the marks go.