Measuring solubility [chemistry only]
2 marks · HardDescribe one safety precaution and one step to ensure accuracy when carrying out a solubility experiment for a solid in water.
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Also accept: Wear eye protection to avoid injury from hot or splashing liquids. Ensure all water is evaporated by heating to constant mass to get an accurate mass of solute.; Use eye protection as a precaution. To ensure accuracy, heat to constant mass to make sure all water is removed.
Common mistakes: Mentioning unrelated safety precautions, e.g. wearing gloves without reason.; Not mentioning heating to constant mass or omitting a safety precaution.
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Marking points
B1 · 1 mark · States any valid safety precaution (e.g. wear eye protection or heat gently).
B2 · 1 mark · States a step to ensure accuracy (e.g. heat to constant mass, use only solution with no solid, measure mass accurately).
Worked solution
Wear eye protection during heating to prevent splashes from hot liquid or solid. Heat the evaporating basin to constant mass to ensure all water has been removed and the measured mass is only solute.