INTRODUCTION
Diffusion takes place on molecules of liquid, gas or a solution. It is the movement of molecules from an area of higher concentration to an area of lower concentration down a concentration gradient in random motion (D G McKean, Dave Hayward 2014). The diffusion of molecules passing across a lipid bilayer is also affected by its “hydrophobicity”. Diffusion can be done without the use of energy due to the randomness of the movements of particles. Molecules move from areas where they are dominant, to areas where they are in little number without the influence of outside forces. When the particles reached equilibrium, particles will continue to move in both directions without further change in concentration. (Miller, Levine 2008). For example, a perfume sprayed inside a room will only take some time for the aroma to fill the room. The area where the perfume is sprayed is the area with the highest concentration of molecules. As the aroma spreads out, the molecules start to fill the areas with lower concentration which explains the diffusion of particles of the perfume.
Molecular weight is the sum of the atomic weights of the atoms found in a molecule of a substance. (Darrel Ebbing, Steven Gammon 2002). If the molecular weight affects the rate of diffusion, then the higher the molecular weight, the slower the rate of diffusion. This was observed in the experiment where diffusion of hydrochloric acid (HCl) and ammonium hydroxide (NH4OH) were tested. In this