Tag: changes in physical state - boiling, evaporation and condensation

Evaporation that occurs directly from the solid phase below the melting point, as commonly observed with ice at or below freezing or moth crystals (napthalene or paradichlorobenzene), is called sublimation.

A volatile liquid is one that evaporates or vaporizes quickly at room temperature. Volatile liquids have low boiling point. As a result, they evaporate very easily at room temperature. All the above liquids are volatile.

Cotton absorbs water, and thus, causes sweating. Sweat comes out the clothing and in contact with the atmosphere. It evaporates taking up the heat from the surrounding and thus, gives a cooling effect.

A volatile liquid is one that evaporates or vaporizes quickly at room temperature. Volatile liquids have low boiling point. As a result, they evaporate very easily at room temperature.

The process by which molecules undergoes a spontaneous transition from the liquid phase to the gaseous phase is called as evaporation. In evaporation due to increase of temperature rate of evaporation also increases.

Spirit is a volatile liquid which evaporates fastly than water and oil which have higher boiling point as compare to spirit. Grease is heavy, viscous oily material takes longer time to evaporate. Hence, spirit is the liquid which evaporates fastly. 

Evaporation is the surface phenomenon in which liquid molecules of high kinetic energy evaporates fastly from the surface of the liquid. Due to which the molecules of less kinetic energy remains in the solution and the temperature of the liquid decreases. Hence, it cools down. This phenomenon is known as evaporative cooling.

When liquid gets evaporated from the surface of liquid they convert from liquid state to gaseous state by absorbing energy from the liquid and due to it temperature of the liquid decreases.

Crystallisation technique for purification is better than evaporation because
1. The extent of purification in case of crystallisation technique is very high.
2. Does not require very high temperature conditions, there is no need to boil the solvent.
3. The technique does not require very high apparatus setup for performing the purification.
4. If the compound is soluble in one solvent & less soluble or insoluble in other solvents, crystallisation can be done by mixing of the two solvents only.

The water kept in an earthen pot remain cool even in summer because earthen pot has many small holes. Water seeps out through them and evaporates from the surface of the pot. The energy needed for evaporation is taken from the water kept in the earthen pot. As a result, water kept in earthen pot become cool.