Important concepts

1. Important concepts 1- Vapour pressure 2- Difference between Vaporization and Evaporation

2. What is meant by vapor pressure ?

3. Vapour pressure • Also Called equilibriumvapour pressure. • Vapour pressure is the pressure exerted by a vaporwhich is inthermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system.

4. Why it is indication to volatility? • It reflects the tendency of particles to escape from the liquid (or a solid). • A substance with a high vapour pressure at normal temperatures is often referred to as volatile substance.

5. Why it is indication to volatility? - Theatmospheric pressure boiling point  of a liquid (also known as the normal b.pt.)is the temperature at which the vapour pressure equals the ambient atmospheric pressure. - With any incremental increase in that temperature, the vapour pressure becomes sufficient to overcome atmospheric pressure and lift the liquid to form vapor bubbles.

6. Vaporization versus Evaporation • Vaporization is a more general term and applies to both evaporation and boiling. • Where vaporization is any process that describes the conversion of a liquid to a gas. • Evaporationoccurs below the boiling point where particles of the liquid (or solid) go from the surface to the vapor state. • Boilingis a more particular process where a liquid goes to the vapor state at the temperature where the vapor pressure is equal to the ambient pressure. In boiling, vaporization can occur anywhere within the body of the liquid, not just at the surface.