A student plans to electrolyse concentrated sodium chloride solution using carbon electrodes and a 6 V power pack. Chlorine gas forms at the positive electrode and hydrogen gas forms at the negative electrode. Sodium hydroxide forms in the solution. The student plans to collect each gas in a test tube and then test it.
The table gives hazard information about the substances.
| Substance | Hazard information |
|---|---|
| concentrated sodium chloride solution | low hazard |
| chlorine | toxic if breathed in; irritates the eyes and lungs |
| hydrogen | extremely flammable |
| sodium hydroxide solution | irritant when dilute; corrosive when concentrated |
Chlorine carries a hazard symbol showing a skull and crossbones. State what this symbol means.
Describe the test for chlorine and give the result.
Suggest why the student should test only a small test tube of hydrogen with a lighted splint.
Evaluate the risks in the student's plan and suggest suitable precautions.
230 exam-style questions on Edexcel GCSE Chemistry 1.1 Formulae, equations and hazards, covering 1.1.1 Formulae, word and balanced equations, 1.1.2 Balanced ionic equations, and 1.1.3 Hazard symbols and risk in practical work. Each one has a worked solution and a mark scheme showing where the marks go.