What Is The Evaporation?

The Evaporation

Evaporation: Take some water in dish. The water in the dish will disappear after some time. It is because the molecules of water are in constant motion and possess kinetic energy. Fast moving molecules escape out from the surface of water and goes into atmosphere. This is called evaporation.

"Evaporation is the changing in liquid into vapors (Gaseous state) from the surface of the liquid without heating it".

Unlike boiling, evaporation takes place at all temperature but only from the surface of the liquid. The process of boiling takes place at a certain fixed temperature which is the boiling point of that liquid. At boiling point, a liquid change into vapors not only from the surface but also with in the liquid. These vapors comes out of the boiling liquid as bulbs which breakdown on reaching the surface.

Evaporation play an important role in our daily life. Wet clothes dry up rapidly when spread. Evaporation causes coiling. Why? During evaporation fast moving molecules escape out from the surface of the liquid. Molecules that have lower kinetic energies are left behind. This lower the average kinetic energy of the liquid molecules and the temperature of the liquid. Since temperature of the substance depends on the average kinetic energy of its molecules. Evaporation of perspiration helps to cool our bodies.

  Evaporation takes place at all temperature from the surface of liquid. The rate of evaporation is affected by various factors.

TEMPERATURE

Why wet clothes dry up more quickly in summer than in winter? At higher temperature, more molecules of liquid are moving with high velocities. Thus, more molecules escape from its surface. Thus, evaporation is faster at high temperature than at low temperature.

SURFACE AREA

Why water evaporates faster when spread over large area? Large is the surface area of a liquid, greater number of molecules  has the chance to escape from its surface.

WIND

Wind blowing over the surface of liquid sweeps away the liquid molecules that have just escaped out. This increases the chance for more liquid molecules to escape out.

NATURE OF THE LIQUID

Does spirit and water evaporate at the same weight? Liquids differ in the rate at which they evaporate. Spread a few drops of ether or spirit on your palm. You feel cold, why?