Why osmosis happens

Solutions with a high concentration of solute molecules, such as sugars or salts, have a low concentration of water molecules and vice versa.

The net movement of water from a region of high water concentration to a region of low water concentration through a selectively permeable membrane.

This means osmosis is a special case of diffusion: the diffusion of water. Osmosis is one of the most important biological processes in living things for it is the method allowing water to spread around the cells; without water, the cells will die. This Resource Guide on Osmosis will illustrate how important this process is to survival.

Osmosis is the passage of water from a low solute concentration area through a semi-permeable membrane to a high solute concentration area to equalize the solute concentrations on both sides. A solvent is the base substance, where a solute is being dissolved and the result is the solution.

Through osmosis, water is provided to the cells of your body; it plays a significant role in the preservation of life. It is this process that helps plants receive water and is even used in kidney dialysis. Temperature - The higher the temperature, the faster the water molecules move across the semi permeable membrane. Surface Area - The larger the surface area, the more space for the molecules to move easily across; the smaller the area, the more restricted the movements of the molecules and the slower the movement.

Difference in Water Potential — The higher the difference in water potential, the faster the osmosis; for the lesser water molecules are in the region of low concentration, more water molecules from the region of higher concentration can enter faster and easier. Pressure — The more the pressure, the faster the molecules will move for they are being pushed faster across a low concentration. Concentration gradient - The movement of osmosis is affected by the concentration gradient; the lower the concentration of the solute within a solvent, the faster osmosis will occur in that solvent.

Light and dark — They are also factors of osmosis; since the brighter the light, the faster osmosis takes place. Osmotic pressure is a colligative property. In other words, it depends on the molar concentration of the solute but not on its density. Osmosis is the movement of water through a semipermeable membrane according to the concentration gradient of water across the membrane, which is inversely proportional to the concentration of solutes.

Semipermeable membranes, also termed selectively permeable membranes or partially permeable membranes, allow certain molecules or ions to pass through by diffusion. While diffusion transports materials across membranes and within cells, osmosis transports only water across a membrane.

The semipermeable membrane limits the diffusion of solutes in the water. Not surprisingly, the aquaporin proteins that facilitate water movement play a large role in osmosis, most prominently in red blood cells and the membranes of kidney tubules. Osmosis is a special case of diffusion. Water, like other substances, moves from an area of high concentration to one of low concentration. An obvious question is what makes water move at all?

Imagine a beaker with a semipermeable membrane separating the two sides or halves. On both sides of the membrane the water level is the same, but there are different concentrations of a dissolved substance, or solute, that cannot cross the membrane otherwise the concentrations on each side would be balanced by the solute crossing the membrane.