What is osmosis and its application?

Answer 1

http://www.answers.com/topic/osmosis The applications listed on that website are very informative, but the description of osmosis is lacking a few details. It would be a good idea to supplement your reading of that web page with this information:

It is a common misconception that osmosis is the diffusion of water in only one direction. In reality, water molecules will diffuse in both directions during osmosis, but the rate of diffusion from a region of high water potential (low solute concentration) to a region of low water potential (high solute concentration) will be higher than the rate of diffusion back into the region of high water potential/low solute concentration. Thus osmosis is the net movement of water across a semi-permeable membrane, from a region of high (more positive) water potential to a region of low (more negative) water potential. The word 'net' is very important in this definition, as it illustrates that we are referring to the overall effect, rather than individual molecular movements.

It is also important to remember that osmosis does not stop when "there is an equal solute concentration on both sides of the membrane". Osmosis will 'stop' when the water potential on either side of the membrane is equal, which may occur when one side still has a higher solute concentration, since other factors also effect osmosis (eg pressure). Even when osmosis 'stops', water will still diffuse in both directions, but at equal rates (the system has reached equilibrium).