Diffusion of potassium permanganate, image 3 of 4. A piece of potassium permanganate was placed at the bottom of the beaker at 12 o'clock (4 hours ago). It has now diffused throughout the water. The colour is darker than in A500/474, indicating that a more uniform concentration is being achieved throughout the solution. Diffusion is the random movement of molcules in solution eventually leading to a uniform concentraion of the molecules thoughout the solution. Diffusion always occurs from a region of high concentraion to a region of low. For a sequence showing the diffusion, see A350/131, A350/132 and A350/134.