Introduction to Diffusion

Learning Outcomes

After completing this module you should be able to:

  • Explain the linear relationship between the rate of movement of a substance and its concentration gradient (Fick’s First Law).
  • Measure the rate of movement of a substance from one area to another as a function of the concentration gradient and the diffusion coefficient of that substance in the medium.


1: Measuring movement
2: Directed vs undirected movement
3: Measuring movement using flux
4: Gradients and diffusion
5: Visualising the gradient
6: Fick's First Law
7: The gradient in Fick's First Law
8: A familiar equation for Fick's First Law
9: Graphing Fick's First Law
10: How does flux depend on distance?
11: A fragrant example
12: General transport equations and Fick's First Law
13: Summary