Reaction rate – collision model (concentration, temperature, catalyst, surface area)
ChemistryKinetics & EquilibriumAges 15–16
Use it with your class: students open it from a link or a QR code, with no account needed.
Next in Kinetics & Equilibrium
Gas particle A collides with solid B (block or powder); only collisions with enough activation energy form product C. The graph of C particles over time keeps the previous run's curve so you can compare as you raise the concentration of A, raise the temperature (Arrhenius, van 't Hoff rule), add a catalyst, or crush B into powder; the average rate and the effective-collision probability update live. Two more views show the Maxwell–Boltzmann energy distribution with a movable Ea line (the shaded fraction with E ≥ Ea at two temperatures, with or without a catalyst) and an Arrhenius plot of ln k against 1/T for finding Ea from the gradient.
Lesson: Factors affecting reaction rate
What it shows
Collision theory explains reaction rate at the particle level: particles must collide, and only collisions with at least the activation energy Ea lead to products. A higher concentration makes collisions more frequent, powdering a solid exposes more surface, and a catalyst provides a pathway with a lower Ea. The Energy distribution view shows why temperature matters so much: the Maxwell–Boltzmann curve flattens and spreads to higher energies while its area stays the same, so the fraction of particles with E ≥ Ea rises sharply. The Arrhenius plot view links this to the rate constant, k = A·e^(−Ea/RT), and finds Ea from the gradient of ln k against 1/T.
How to use
In Particles, run the default settings, press Reset (keep previous curve) and change one factor, such as T +10 °C or the catalyst, to compare the slope with the gray curve. In Energy distribution, move the Ea slider or drag on the graph, tick Compare with T₂ and compare the shaded fractions. In Arrhenius plot, press Measure k at T at several temperatures and read Ea from the line of best fit.
Parameters you can change
- Number of A particles (concentration) 10–80 particles
- Temperature 0–100 °C
- Catalyst present
- Form of solid B Block (small surface area), Powder (large surface area)
- View Particles, Maxwell–Boltzmann energy distribution, Arrhenius plot (ln k against 1/T)
- Activation energy Ea (no catalyst) 10–100 kJ/mol
- Comparison temperature T₂ 0–500 °C
- Also draw the curve at T₂
Questions to explore
- Why does powdered coal burn much faster than a lump of coal of the same mass?
- Raising the temperature increases the rate for two reasons. What are they, and which one matters more?
- Is a catalyst used up in the reaction, and how does it speed up the formation of C?
Teaching ideas
All guides- Rates of Reaction Virtual Lab: Acid Concentration and GasA rates of reaction virtual lab for the GCSE gas-collection practical: react marble chips with acid, record gas volume over time and compare concentrations.
- Enzyme Activity Virtual Lab: Temperature and pHEnzyme activity virtual lab: measure amylase activity across temperature and pH, find each optimum, calculate Q10 and watch denaturation happen.
- Disappearing Cross Virtual Lab: Concentration and RateA disappearing cross virtual lab for the GCSE rates practical: time sodium thiosulfate and acid, plot 1/t against concentration and test temperature.
