Order of reaction
What Order of reaction means in Chemistry A-Level, as defined for AQA, OCR.
Definitions of Order of reaction
Exam boards and our study guides word this term in slightly different ways. Learn the version your board uses.
Check what you remember
Read the wording for your board, then hide it and explain Order of reaction in your own words. Rough notes are fine. This is a self-check, with no mark or grade.
Reference: OCR
Revealed by the shape of the line: a horizontal line means zero order, a straight line through the origin means first order, and an upward curve of increasing steepness means second order.
A value of 0, 1 or 2 with respect to a reactant, deduced from the shape of the graph of rate against concentration.
The power to which the concentration of a reactant is raised in the rate equation.
Topics that use Order of reaction
- Rate equations (A-level only) (AQA A-Level)
- How fast? (OCR A-Level)
Related terms
- Overall order
- Rate equation
- rate of reaction
- Rate-determining step
- units of k
- zero, first and second order
- Calculating rate and concentration from the rate equation
- Colorimetry
Using Order of reaction in the exam
Check the command word and mark scheme for your exact question. After comparing your explanation with the reference, use the term in an answer on the linked topic. This practice does not predict an exam mark.
Practise Chemistry questions
Create a free account to answer exam-style questions on this topic and get feedback on your answers.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge