Question

Distinguish between evaporation and boiling.

Answer 1

Hint: The evaporation is the process of conversion of surface liquid into the vapours slowly without use of outer energy. While boiling is the process in which the vapour pressure of a liquid is risen equal to its atmospheric pressure such that it gets converted into gas form.

Complete answer :
Let us see the difference between evaporation and boiling in table-

S. No.	Evaporation	Boiling
1.	It involves the change of liquid into a gaseous state.	During boiling, the vapour pressure of liquid is increased to atmospheric pressure so that it changes into vapour.
2.	It is a natural process.	Boiling is an unnatural process.
3.	It occurs only on the surface of the liquid. Thus, it is called as surface-phenomenon.	The boiling takes place within the entire mass.
4.	It is a slow process.	It is rapid, depending upon the heat provided.
5.	No bubbles are formed in the liquid being evaporated.	One can see the bubbles formed when a liquid is heated up.
6.	The evaporation can take place at any temperature.	The boiling of liquid occurs at the boiling point. Every liquid has a specific boiling point.
7.	It can take place below the boiling point temperature.	It takes place at a higher temperature than the evaporation.
8.	It does not require extra heat from outside.	It requires a high amount of energy from the outside.
9.	Example - The clouds are formed from evaporation of water of sea	Example - When we heat up the water in a container, we boil it.

Note :
- The Evaporation is dependent on surface area. With increase in surface area, the evaporation also increases. Even with rise in temperature, the rate of evaporation increases.
- The boiling point of a liquid depends upon its atmospheric pressure. At higher atmospheric pressure, the boiling point rises while with decrease in the atmospheric pressure, the boiling point decreases. Further, the presence of impurities also affect the boiling point. If a non-volatile impurity is present in a substance, it will increase its boiling point.