Can anyone explain osmosis and reverse osmosis?

Question

I am only in my second year of highschool, so please do keep your terms simple. I'm entering this competition, much like a science fair, and I have to demonstrate osmosis and reverse osmosis-- Only one problem. I don't even know what osmosis is. Please explain, and if you have any ideas on how to demonstrate it, please do tell. Thanks.

Answer 1

To understand how reverse osmosis water purification works, you must first know the definition of osmosis. And just in case you don’t remember this from high school science class, here it is! Osmosis describes water moving or passing from an area of high water concentration to an area of low water concentration through a semipermeable membrane. Clear as mud, right?

We usually think of osmosis in terms of cells. Water molecules are small enough to freely pass through cell walls. If your body is retaining water, and you feel bloated and puffy, the cells are holding a high concentration of water. Osmosis occurs when the water moves out of those cells into other areas of the body, and the puffiness goes away. Osmosis basically equalizes the water on the two sides of the membrane. The cells and fluids want to be in a state of equality. In our bodies, water is drawn to the areas that have higher concentrations of salt to equalize the concentrations.

In reverse osmosis water purification, we want to remove impurities like sediment, nitrates and other substances. A pump forces water through a filter drawing the pure water molecules away from the contaminants. The pure water passes through the filter for use by the consumer, while the contaminated water is discarded. This process for water purification produces very high quality water both for drinking or for routine laboratory uses.

Reverse osmosis

Encyclopedia definition.Reverse osmosis is a technological term developed from osmosis. Osmosis is a natural phenomena occuring in live cells where solvent molecules (usually water) will flow from a low solute region to a high solute region through a semipermeable membrane. The semipermeable membrane is referring to cell membrane or any membrane that has a similar structure or contituents to cell membrane. The movement of the solvent continues until an equilibrium of concentration is achieved on both sides of the membrane.

Reverse Osmosis is the process of forcing a solvent from a region of high solute concentration through a membrane to a region of low solute concentration by applying a pressure in excess of the osmotic pressure. In simpler terms, reverse osmosis is pushing a solution through a filter that traps the solute from one side and allows the obtainment of the pure solvent from the other side.