A factory produces crude coconut oil that contains small solid plant fibres and excess water. Describe how the factory could obtain a sample of pure, dry coconut oil from this mixture.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
1. Filter the mixture to remove the solid plant fibres.
2. The oil and water pass through as the filtrate; the fibres remain as residue.
3. Separate the oil from the water using a separating funnel, exploiting that oil and water are immiscible and form two layers.
4. Dry the oil by adding a drying agent such as anhydrous calcium chloride or anhydrous sodium sulfate, then filter off the drying agent to obtain pure, dry coconut oil.
2. The oil and water pass through as the filtrate; the fibres remain as residue.
3. Separate the oil from the water using a separating funnel, exploiting that oil and water are immiscible and form two layers.
4. Dry the oil by adding a drying agent such as anhydrous calcium chloride or anhydrous sodium sulfate, then filter off the drying agent to obtain pure, dry coconut oil.
Examiner tips
- Use the exact sequence: filter → separating funnel → drying agent → final filtration.
- Mention that oil and water are immiscible and form two layers.
- Show the drying agent name and that it removes water.
- Keep the answer concise and use correct terminology.
Mark scheme (4 marks)
- Filter the mixture to remove the solid plant fibres
- The oil (and water) passes through as the filtrate; fibres remain as residue
- Separate the oil from the water using a separating funnel (as oil and water are immiscible / form two layers)
- Dry the oil by adding a drying agent such as anhydrous calcium chloride / anhydrous sodium sulfate, then filter off the drying agent
Related
- All Cambridge International IGCSE Chemistry (0620) revision notes →
- How to answer a "Describe" question →
- Decode the mark scheme abbreviations →