P1- 1.6

Seite 1

P1- 1.6- EVAPORATION AND CONDENSATION

Drying off:

When you hand wet clothes on a washing line, eventually they will dry off. This is because the water evaporates.

Condensation:

In a steamy bathroom, a mirror is often covered by a film of water. They are lots of water molecules in the air. Some of them hit the mirror, cool down and stay there. We say that the water vapour in the air condenses on the mirror.

Factors affecting the rate of condensation:

-Increasing the surface area

-Reducing the surface temperature

Cooling by evaporation:

-Weak attractive forces exist between the molecules in the liquid

- The faster molecules which have more kinetic energy break away from the attraction of the other molecules and escape from the liquid

- After they leave the liquid is cooler because the average kinetic energy of the remaining molecules in the liquid has decreased

Factors effecting the rate of evaporation::

- Increasing the surface area of the liquid

- Increasing the temperature of the liquid

- Creating a draught of air across the liquids surface