Diffusion is the movement of
particles of a substance in between the particles of another substance. Diffusion
occurs slowest in solids, faster in liquids and the fastest in gases. This is
due to the different arrangement of particles in solid, liquid and gas. The
particles of a solid are packed closely together whereas the particles of a
liquid are packed slightly loose. The particles of a gas are very far apart
from each other and in a random arrangement.
The purple color of
potassium manganite (VII), KMnO4 solution spreads slowly throughout
the water. After a few hours, the water turns uniformly purple.