An air freshener changes the scent of a room by the process of diffusion. Diffusion is a natural phenomenon in which any substance (molecules, species) move from higher concentration to lower concentration. In diffusion particularly no semi permeable membrane (spm) exists. Its a passive movement of molecules from higher concentration to lower concentration. The molecules move like this until the concentration gradient becomes equal. This condition is known as equilibrium condition and after the equilibrium has been achieved there is no net movement of molecules.
