Evaporation

Some  volatile liquids , for example, Petrol and Alcohol changes from its liquid state to gaseous state without application of heat. The molecules of the liquid gradually escape from the surfaces of the liquid causing the liquid to change to its vapour form. This process is called evaporation.

Evaporation can be defined as a process whereby liquid changes to vapour .

Factors affecting evaporation of liquids.

The following factors affect evaporation of liquids

1. Pressure : when there is increase in pressure in the surface of the liquid, the rate of  evaporation decrease .
2. Temperature : increase in temperature increases the rate of evaporation.
3. The nature of the liquid: different liquid evaporates at different rate . water and petrol evaporates at different rate .  The lower the boiling point of a liquid the higher the rate of evaporation
4. Surface area of the liquid: the higher the surface area the higher the rate of evaporation.
5. Weather condition: when there is dry air and harmattan , evaporation increases .

Evaporation causes cooling

When you use a hand sanitizer that is made from alcohol or when you spray a methylated spirit at the back of your hand, you feel coolings in your hand. This is because of the evaporation of the alcohol in the sanitizer and the methylated spirit.

In the same way, water stored in earthen pots is cooler than that stored in glass bottles. Evaporation takes place through the pores of the pots causing the water to cool .

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