Dilution: a substance is put in a solvent to reduce its concentration
Diffusion: The movement of particles from an area of high concentration to an area of low concentration
Experiment 1, Diffusion
Hydrochloric acid is placed at one end of a tube, ammonia solution at the other.
Where they meet a ring of ammonium chloride appears.
The diagram shows it is closer to the HCL end.
From this we can tell that ammonia must have travelled faster, as it got further in the time. Lighter particles travel faster- so we can tell that ammonia is a lighter gas.
Experiment 2, Dilution
Put a coloured substance in a solvent e.g food colouring in water.
You can see that over time the colour levels out but is weaker than the original colour- this is dilution.
Dilution at different temperatures: more heat; means more energy; means more movement; so the particles can move to different areas more quickly. So applying heat decreases the amount of time taken for the coloured substance to be fully diluted.