Diffusion
Diffusion is the spreading of particles from a region of high concentration to one of low concentration by random movement.
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Diffusion is the spreading of particles from a region of high concentration to one of low concentration by random movement.
- Happens faster at higher temperatures
- Lighter particles diffuse faster
- Perfume spreading across a room is an example
🧠 Quick quiz
Three questions. Score 2 or more to complete the topic.
What is Diffusion?
Within Chemistry, which covers atoms, bonding, reactions, the periodic table, organic chemistry and the chemistry of everyday life, this topic explains Diffusion. Chemistry links what you can see in the lab to the particles and bonds behind it, so each topic here shows that link in a model.
Check that you can explain Diffusion in your own words and give one example from everyday life. If you can do that, you have understood the core idea.
Understanding Diffusion helps you explain why substances behave as they do, from cleaning products and food to medicines.
Diffusion in detail
Diffusion is the spreading out of particles from an area of high concentration to an area of low concentration, caused by their random movement. It happens in gases and liquids but not noticeably in solids. A smell spreading across a room and a drop of ink in water are classic examples.
The rate of diffusion is faster at higher temperatures because particles move faster, and lighter particles diffuse faster than heavier ones, as shown in the ammonia and hydrogen chloride experiment, where the white ring forms nearer the heavier hydrogen chloride. Diffusion is essential in living cells for moving oxygen and nutrients.
How the interactive helps you understand Diffusion
Watch the gas particle model in the interactive. Use any sliders or buttons it offers to change the values and see how the gas particle model responds.
Before you change anything, predict the result. Then change one value at a time and check whether your prediction was right. This is a quick way to build a correct mental model of Diffusion.
Real-life uses and examples
- Link Diffusion to everyday products such as cleaning agents, food and medicines.
- Read a chemical equation or diagram and work out what Diffusion shows.
- Explain Diffusion in an exam by linking the particles involved to what you observe.
Common mistakes to avoid
- Mixing up the names of substances or ions when you describe Diffusion.
- Describing what happens without explaining the particles or bonds involved.
- Learning the definition without testing it. Use the quiz and the interactive to check that you can apply the idea.
Frequently asked questions about Diffusion
What is Diffusion?
Diffusion is the spreading of particles from a region of high concentration to one of low concentration by random movement.
What are the most important points about Diffusion?
The main points are: Happens faster at higher temperatures; Lighter particles diffuse faster; Perfume spreading across a room is an example.
Why is Diffusion useful?
Understanding Diffusion helps you explain why substances behave as they do, from cleaning products and food to medicines.
How can I practise Diffusion?
Open the interactive at the top of this page and change the controls one at a time. Predict the result before each change, then take the three-question quiz. A score of two or more marks the topic as complete on this device.
Which topics are related to Diffusion?
Related topics in Chemistry include Electron Configuration, The Periodic Table, Group 7: Halogens.