A student makes copper sulfate crystals. The method is:
Warm 50 cm3\mathrm{cm^{3}}cm3 of dilute sulfuric acid in a beaker using a water bath.
Add copper oxide powder, a spatula at a time, until some remains unreacted.
Filter the mixture.
Heat the filtrate in an evaporating basin, then leave it to crystallise.
The table shows part of the student's risk assessment.
| Hazard | Risk | Precaution |
|---|---|---|
| dilute sulfuric acid is an irritant | acid splashes into the eyes | wear eye protection |
| copper oxide powder is harmful | powder is breathed in or swallowed | ? |
| hot evaporating basin | burns to the hands | ? |
Explain the difference between a hazard and a risk.
Suggest a precaution for the risk from copper oxide powder.
Suggest a precaution for the risk from the hot evaporating basin.
The student decides to heat the filtrate strongly until all the water has evaporated. Explain why this increases the risk, and suggest a safer way to carry out step 4.
Concentrated sulfuric acid is labelled corrosive, but dilute sulfuric acid is labelled irritant. Suggest why the teacher gives the class dilute acid.
47 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.