Osmosis is the net diffusion of water from a weak solution to the more concentrated solution when the two are separated by means of a semipermeable membrane. If the solution is separated from its pure solvent the molecules of solvent move from pure solvent to the solution. The movement of water occurs, in osmosis, due to the difference of chemical potential on two sides. The molecules of water move from a solution having more potential to the solution having less potential. Pure water has maximum water potential ., it has maximum number of free and active water molecules.