Loading please wait

The smart way to improve grades

Comprehensive & curriculum aligned

Try an activity or get started for free

Understand Collision Theory

Worksheet Overview

The speed of a chemical reaction makes a big difference to its effects.

Fireworks involve metals reacting with oxygen in a fraction of a second...

 

Fireworks

 

... but rusting happens over a period of years.

 

Rusty metal

 

We can describe this difference by studying the behaviour of particles in something called collision theory. This can be used to explain why some reactions are fast and some are slow, and helps people to make good reactions (such as pretty fireworks) go faster, and bad reactions (such as rusting) go more slowly.

 

Rates of reaction

Suppose we start a chemical reaction and record how much product is made over a period of time. Unless something very strange happens, the graph will look like this:

 

Graph to show volume of gas produced

 

The first part of the graph is a straight line - this is also the time when the reaction is fastest. As time passes, the reaction starts to go more slowly, then it stops. The reaction rate tells us how quickly the reaction happens.

 

To work out the rate of reaction, we calculate:

 

rate of reaction = amount of product  ÷ time taken

 

For example, if a reaction makes 15 g of product in 50 seconds, we would do this calculation:

Rate of reaction = 15 g ÷ 50 s = 0.3 g / s.

 

Collision theory

There are several factors which change the rate of reaction. One big idea links them all and this is collision theory.

 

For two particles to react, they have to collide in the right orientation and with enough energy to break the atomic bonds in the particles.

The more frequently these collisions happen, the faster the rate of reaction will be.

 

Once we understand collision theory, we can explain why some reactions are fast and some are slow. We can also speed up or slow down reactions if that is what we need to do.

What is EdPlace?

We're your National Curriculum aligned online education content provider helping each child succeed in English, maths and science from year 1 to GCSE. With an EdPlace account you’ll be able to track and measure progress, helping each child achieve their best. We build confidence and attainment by personalising each child’s learning at a level that suits them.

Get started
laptop

Try an activity or get started for free

  • educational
  • bettfutures
  • cxa
  • pta
  • era2016
  • BDA award
  • Explore LearningTuition Partner
  • tacm