All calculations
Mean rate of reaction
Rates of reaction
AQA 8462
ORIGINAL
mean rate = amount of reactant used or product formed / time
Rate is a change divided by the time interval, with both quantities carrying units.
Verified against AQA 8462 (2026 spec)
Work it, then mark it
Do each calculation on paper first, then reveal the mark scheme and tick the marks you actually earned — the same way you should mark past papers.
Q1
2 marks
A reaction produces 72 cm3 of gas in 90 s. Calculate the mean rate of gas production.
Do the calculation on paper first — then mark it.
Where the marks get lost
- Multiplying amount by time.
- Giving a number without compound rate units.
Exam tip: Read the time interval carefully: final time minus initial time, not always the final time alone.
Calculations are the most trainable marks in chemistry
They come up every paper and reward a clean method. Send me one you keep dropping marks on — your first lesson is free.