AS · Formulae, moles and stoichiometry
Quantitative chemistry
Follow a three-stage amount-of-substance calculation and earn credit for method, ratios and units.
- Calculation
- Error carried forward
- Units
OCR A A-level Chemistry A H432
Try three free OCR A Chemistry A ExamBOT questions
Choose a focused H432 question and see how ExamBOT responds to the working, chemistry and structures that earn marks.
- Three original, seven-mark H432 questions
- Feedback linked to the working and chemistry in your answer
- Calculation, practical-evaluation and molecule-building skills
No account needed · About 6–8 minutes each · Anonymous attempts expire after seven days
Choose your skill
Which question will you try?
AS · Physical chemistry and evaluation
Enthalpy practical
Interpret calorimetry data, calculate an enthalpy change and improve the experimental method.
- Data handling
- Multi-step maths
- Practical evaluation
AS · Basic organic concepts
Organic molecule builder
Reason from a molecular formula, construct the required molecule and justify its classification.
- Molecule builder
- Skeletal formulae
- Chemical reasoning
Focused formative practice
What happens in the demo
Show your method
Write calculations and explanations naturally, or build the requested chemical structure.
Check each part
See which marking points your answer covers and where a missing step could cost a mark.
Use Sherlock Moles
Ask for a targeted hint that helps you make the next decision without giving away the answer.
Independent practice for OCR A Chemistry A
These are original ChemistryUK questions informed by exam formats and examiner expectations. They are formative practice, not official OCR assessments or grades.