O-Level Chemistry Paper 3 Planning Scenario Bank
Download printable cheat-sheet (CC-BY 4.0)08 Nov 2025, 00:00 Z
Join our Telegram study groupTL;DR
Planning contributes about 15 % of Paper 3, and candidates must outline variables, safety controls, apparatus, and data treatment under time pressure.
This scenario bank offers short prompts spanning the core experiment families so you can drill Planning responses before tackling full practicals.
Pair each scenario with MMO/PDO/ACE reflections to internalise how planning choices drive execution and evaluation.
1 | How Planning is assessed
- SEAB’s assessment objectives specify that Planning requires candidates to identify variables, outline procedures, describe data treatment, and address risks (SEAB 2026 syllabus, p. 25).
- Planning scenarios often integrate content from multiple topics, so cross-referencing other guides (titration, kinetics, separation) strengthens responses.
- Aim to complete each scenario in 6–8 minutes, matching Paper 3 pacing.
2 | Scenario checklist
For each prompt, make sure your outline covers:
- Aim. What you are investigating (variable, outcome).
- Variables. Independent, dependent, controlled, plus how to manage them.
- Apparatus. Specific items from SEAB’s list (e.g., 25 cm³ pipette, polystyrene cup, condenser).
- Procedure. Logical steps with timings/volumes.
- Data use. How results will be processed (graphs, calculations).
- Safety. PPE, disposal, and hazard mitigation.
- Quality improvements. Optional but useful for stretching into ACE.
3 | Scenario bank
3.1 | Salt preparation — acid with insoluble base
- Prompt. Plan an experiment to prepare pure zinc sulfate crystals using dilute sulfuric acid and excess zinc oxide.
- Focus points. Heating control, filtration, crystallisation, yield calculation.
- Stretch. Include how you would compare actual versus theoretical yield.
3.2 | Precipitation separation
- Prompt. Outline how to prepare and dry pure barium sulfate by reacting aqueous barium nitrate with sodium sulfate.
- Focus points. Stoichiometric volumes, washing steps, drying method, waste disposal.
- Stretch. Discuss how to confirm the precipitate is free from soluble impurities.
