A student uses inert graphite electrodes to electrolyse sodium bromide in two experiments. In one experiment the sodium bromide is molten. In the other experiment the sodium bromide is dissolved in water. The observations at the negative electrode are shown in the table.
| State of sodium bromide | Observation at the negative electrode |
|---|---|
| Molten | A metal forms |
| Dissolved in water | Bubbles form |
State the product at the negative electrode in each experiment and explain why the products are different.
The student repeats the experiment using aqueous sodium nitrate. Predict the gas formed at the positive electrode and explain why it is different from the product at the positive electrode when aqueous sodium bromide is electrolysed.
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.