Each collision alters the direction of the molecules movement, so that the path of any one. Since a molecule may at any instant be moving in any direction, such movement is random, The molecules of any substance, be it solid, liquid, or gas, are in a continuous state of movement or vibration, and the warmer a substance is, the faster its molecules moves. The avg speed of this thermal motion depends upon the mass of the molecule. In solutions, such rapidly moving molecules, undergoing millions of collisions every second. molecules becomes unpredictable with no preferred direction of movement. Many processes in living organisms are closely associated with diffusion. For example, oxygen, nutrients, and other molecules enter and leave the smallest blood vessels (capillaries) by diffusion, and the movement of many substances across plasma membranes and organelle membranes occurs by diffusion. Initially glucose is present in compartment 1 at a concentration of 20mmol/l, and there is no glucose in compartment 2.