AQA Chemistry Rate of reaction

Choose a revision tool

Start revising Rate of reaction

Quick active recall practice

Quick multiple-choice practice

Mixed practice and exam-style prompts

Structured topic notes

Timed score-based practice

Full topic guide

Syllabus checklist

43 objective pages available

Calculating rates of reactions10 objectives

Define rate of reaction as the speed at which reactants are used up or products are formed.
Calculate mean rate of reaction using quantity of reactant used divided by time taken. (MS 1a)
Calculate mean rate of reaction using quantity of product formed divided by time taken. (MS 1a)
Use units such as g/s, cm3/s or mol/s for rate of reaction calculations.
Interpret rate data from tables and graphs.
Draw and use tangents to estimate rate of reaction at a specific time from a curve. (MS 3b, MS 3c)
Compare rates of reaction using graph gradients.
Describe why the rate usually decreases as a reaction proceeds.
Link a steeper graph gradient to a faster reaction rate.
Calculate rate from changes in mass or gas volume over time.

Factors which affect rates of chemical reactions14 objectives

State that concentration of solutions affects reaction rate.
Explain that increasing concentration usually increases reaction rate.
State that pressure of reacting gases affects reaction rate.
Explain that increasing gas pressure usually increases reaction rate.
State that surface area of solid reactants affects reaction rate.
Explain that increasing surface area usually increases reaction rate.
State that temperature affects reaction rate.
Explain that increasing temperature usually increases reaction rate.
State that catalysts affect reaction rate without being used up.
Describe methods for investigating factors that affect reaction rate. (AT 1, AT 3, AT 5, AT 6)
Describe the reaction between sodium thiosulfate solution and hydrochloric acid as a practical method for investigating rate. (AT 1, AT 3, AT 5, AT 6)
Describe collecting gas or measuring mass loss as practical methods for investigating reaction rate. (AT 1, AT 3, AT 5, AT 6)
Control variables when comparing reaction rates in practical work.
Use rate data to identify the effect of changing concentration, pressure, surface area, temperature or catalyst. (WS 2.2)

Collision theory and activation energy11 objectives

Explain that chemical reactions happen when particles collide.
Explain that only collisions with sufficient energy lead to reaction.
Define activation energy as the minimum energy needed for particles to react.
Explain that increasing concentration increases collision frequency in solutions.
Explain that increasing gas pressure increases collision frequency.
Explain that increasing surface area increases the number of exposed particles available for collisions.
Explain that increasing temperature increases particle speed.
Explain that increasing temperature increases collision frequency.
Explain that increasing temperature increases the proportion of particles with energy equal to or greater than activation energy.
Use collision theory to explain rate changes in practical observations.
Distinguish collision frequency from collision energy when explaining rate changes.

Catalysts8 objectives

Define a catalyst as a substance that changes the rate of a chemical reaction but is not used up.
Explain that catalysts provide a different reaction pathway.
Explain that a catalyst pathway has a lower activation energy.
Use reaction profiles to compare catalysed and uncatalysed reactions.
Explain why catalysts increase reaction rate using activation energy.
State that catalysts are not included in the overall chemical equation for the reaction.
Describe enzymes as biological catalysts.
Evaluate the use of catalysts in industrial reactions from given information.

rate of reactionmean ratemean rate of reactionunits of rategraph interpretationtangentgraph gradientdecreasing ratereaction rate

Understand Rate of Reaction: Use define the rate of reaction clearly as the speed at which reactants are consumed or products are formed.
Practice Rate Calculations: Use regularly practice calculating the mean rate of reaction using the formula: mean rate = quantity of reactant used / time taken.

Misidentifying the rate unit: Always pair the rate with the appropriate unit that matches the measured quantity: if you are using mass, use g s⁻¹; if volume, use cm³ s⁻¹; if moles, use mol s⁻¹. Write the unit as a fraction (e.g., g s⁻¹) rather than a product (g s).
Confusing Rate Calculation: Remember that the mean rate of reaction is calculated by dividing the quantity of reactant used by the time taken. Ensure you set up the formula correctly as mean rate = quantity of reactant used / time.

Choose a learning objective

Objectives are grouped by subtopic so students can jump straight to the exact skill they want to revise.