* Osmotic pressureis the minimumpressurewhich needs to be applied to asolutionto prevent the inward flow of its puresolventacross asemipermeable membrane.It is also defined as the measure of the tendency of a solution to take in pure solvent byosmosis.Potential osmotic pressureis the maximum osmotic pressure that could develop in a solution if it were separated from its pure solvent by a semipermeable membrane.

Reverse osmosis(RO) is awater purificationtechnology that uses asemipermeable membraneto removeions,moleculesand larger particles from drinking water. In reverse osmosis, an applied pressure is used to overcomeosmotic pressure, acolligative property, that is driven bychemical potentialdifferences of the solvent, athermodynamicparameter

Henry's law states that at a constant temperature, the solubility of a gas in a liquid is directly proportional to the pressure of the gas over the solution.

Applications:

(i) To increase the solubility of CO2in soft drinks and soda water, the bottle is sealed under high pressure.

(ii) Scuba divers must cope with high concentrations of dissolved Nitrogen with breathing air at high pressure underwater. To avoid this air is diluted with He.

(iii) At high altitudes, the partial pressure of oxygen is less than that at the ground level. Low blood oxygen causes anoxia.