Question

20 difference between evaporation and boiling

Answer 1

Evaporation and boiling are two modes of vaporisation a liquid could undergo.

Evaporation is a surface phenomenon. It could take place at all temperatures below the boiling point. For understanding evaporation, we need to understand what is vapour pressure. Vapour pressure is the pressure exerted by a liquid’s vapour on the liquid at phase equilibrium at a particular temperature. Phase equilibrium is attained when an equilibrium is attained between the rates of vaporisation and condensation. When the partial pressure of a liquid is less than the vapour pressure at a given temperature, evaporation takes place. For eg, water kept in a dry room at room temperature will continue to evaporate until the partial pressure equals the vapour pressure at room temperature.

Boiling is a bulk phenomenon. It takes place when the vapour pressure of a liquid exceeds the environmental pressure (mostly atmospheric pressure). This causes the liquid to continue vaporising so as to strike a phase equilibrium but doesn't take place since no amount of vapor can fill the whole environment with vapor.

Answer 2

evaporation is the process that a liquid state changes into gaseous state while boiling means the tepurature at which liquid boils is called boiling point