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New
New
Year 10
AQA
Higher

Collision theory

I can explain why increasing pressure, surface area or concentration increases the frequency of collisions between particles and therefore the rate of reaction.

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New
New
Year 10
AQA
Higher

Collision theory

I can explain why increasing pressure, surface area or concentration increases the frequency of collisions between particles and therefore the rate of reaction.

Download all resources
Share activities with pupils

Lesson details

Key learning points

  1. Particles of reactants in a chemical reaction can react together if they collide with sufficient energy.
  2. Increasing surface area of a solid lets more reacting particles in a solution collide with its particles each second.
  3. Increasing concentration of a reacting solution introduces more reactant particles, so they collide more frequently.
  4. Increasing temperature of reactants increases the speed of particles, so they collide more frequently.
  5. Increasing pressure of reacting gases pushes reactant particles closer together, so they collide more frequently.

Common misconception

That every collision between reactant particles results in a chemical reaction.

The slide deck addresses that not every collision between reactant particles results in a chemical reaction. The particles must collide with the activation energy in order for the collision to be successful and a new product be formed.

Keywords

  • Collision theory - The collision theory is that particles must collide, and with sufficient energy, in order to react.

  • Activation energy - The minimum energy that the particles must have in order to react is known as the activation energy.

  • Rate of reaction - Rate of reaction is the speed with which a chemical reaction takes place, measured by the amount of a reactant used or amount of product formed in a given time.

An engaging way to model the idea of increasing concentration, pressure, surface area and temperature is using students to represent the particles in the reactants.
Teacher tip

Equipment

None required.

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Video

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Starter quiz

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6 Questions

Q1.
In the following reaction identify the reactant: hydrogen peroxide → water + oxygen
Correct answer: hydrogen peroxide
hydrogen
water
oxygen
energy
Q2.
Which solution has the highest concentration?
0.5 g/cm³
1.0 g/cm³
Correct answer: 2.0 g/cm³
0.1 g/cm³
Q3.
Which of the following statements about rate of reaction are true?
Correct answer: It is the speed with which a chemical reaction takes place.
It can be measured by the amount of reactant used × time taken.
Correct answer: It can be measured by the amount of reactant used ÷ time taken.
It can be measured by the amount of product formed.
It can be measured by the amount of product formed × time taken.
Q4.
A student has 5 g of calcium carbonate. How can they increase the surface area of the calcium carbonate?
heat the calcium carbonate
use a mass of 10 g of calcium carbonate
increase the density of the calcium carbonate
Correct answer: crush the calcium carbonate
Q5.
On a volume versus time graph, what does a steep gradient represent?
Correct answer: a high rate of reaction
the rate of reaction is zero
a low rate of reaction
the rate of reaction is not affected by the variable
Q6.
Match the key term to the correct definition.
Correct Answer:collision theory,particles must collide, and with sufficient energy, in order to react

particles must collide, and with sufficient energy, in order to react

Correct Answer:activation energy,the minimum energy that the particles must have in order to react

the minimum energy that the particles must have in order to react

Correct Answer:concentration,the amount of chemical dissolved in a certain volume of solution

the amount of chemical dissolved in a certain volume of solution

Correct Answer:surface area,is the total area of every outer surface of an object

is the total area of every outer surface of an object

Exit quiz

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6 Questions

Q1.
Which conditions must particles of reactants meet in order to react in a chemical rection?
they must be in a liquid state
they must be in a gaseous state
they must have similar energy
Correct answer: they must collide with sufficient energy
thy must be at a high concentration
Q2.
How does increasing the surface area of a solid affect the rate of reaction?
it decreases the rate of reaction
Correct answer: it increases the rate of reaction
it has no effect on the rate of reaction
it changes the colour of the reaction
Q3.
Why does increasing the concentration of reactants typically increase the rate of reaction?
it increases the size of the reactant particles
it decreases the number of successful collisions
it increases the number of successful collisions
it decreases the speed of reactant particles
Correct answer: it increases the frequency of successful collisions
Q4.
What happens when the concentration of a reacting solution is increased?
Correct answer: the reactant particles are more likely to collide
the speed of particles decreases
the particles are more spread out
the reaction becomes slower
Correct answer: there are more reactant particles in the same volume
Q5.
What effect does decreasing the pressure of reacting gases have on the rate of reaction?
it increases the frequency of collisions
the particles move closer together
it increases the pressure of the gases
Correct answer: it decreases the frequency of collisions
more particles have energy higher than the activation energy
Q6.
What effect does increasing the temperature of reactants have on the rate of reaction?
it decreases the speed of particles
Correct answer: it increases the kinetic energy of particles
it decreases the number of collisions
Correct answer: it increases the frequency of successful collisions
it increases the number of particles exposed on the surface of a solid reactant