Question 26
Comment on the following statements:
(a) Evaporation produces cooling.
(b) Rate of evaporation of an aqueous solution decreases with increase in humidity.
(c) Sponge though compressible is a solid.
Comment on the following statements:
(a) Evaporation produces cooling.
(b) Rate of evaporation of an aqueous solution decreases with increase in humidity.
(c) Sponge though compressible is a solid.
(a) Evaporation produces cooling:
In the process of evaporation, liquids change into its vapour at any temperature below its boiling points. For the required phase change, particles either gain or lose energy. During evaporation, the particles of the liquid absorb the energy from the surroundings. The particles in the liquid gain the required kinetic energy to overcome the force of attraction between its particles and escape into the atmosphere.As the energy is absorbed, it results in cooling of the surroundings. Hence, evaporation results in cooling.
(b) The rate of evaporation of an aqueous solution decreases with an increase in humidity:
The moisture present in the atmosphere is called humidity. The air around us can hold a definite amount of water vapour at a given temperature. Hence dry atmosphere can hold more water molecules than a humid atmosphere. As a result, the rate of evaporation of aqueous solution decreases with the increase of humidity and vice versa.
(c)Sponge though compressible is solid:
A sponge is made up of pores filled with air. When a sponge is compressed the air trapped in the pores is expelled out. When it is released, pores again is filled with the air and the sponge comes back into its original shape.
Therefore, a sponge is compressible because of the air trapped in its pores and not because of the space between its particles as what happens in the case of gases.
Hence, a sponge is solid though it is compressible.
(a) Evaporation produces cooling:
In the process of evaporation, liquids change into its vapour at any temperature below its boiling points. For the required phase change, particles either gain or lose energy. During evaporation, the particles of the liquid absorb the energy from the surroundings. The particles in the liquid gain the required kinetic energy to overcome the force of attraction between its particles and escape into the atmosphere.As the energy is absorbed, it results in cooling of the surroundings. Hence, evaporation results in cooling.
(b) The rate of evaporation of an aqueous solution decreases with an increase in humidity:
The moisture present in the atmosphere is called humidity. The air around us can hold a definite amount of water vapour at a given temperature. Hence dry atmosphere can hold more water molecules than a humid atmosphere. As a result, the rate of evaporation of aqueous solution decreases with the increase of humidity and vice versa.
(c)Sponge though compressible is solid:
A sponge is made up of pores filled with air. When a sponge is compressed the air trapped in the pores is expelled out. When it is released, pores again is filled with the air and the sponge comes back into its original shape.
Therefore, a sponge is compressible because of the air trapped in its pores and not because of the space between its particles as what happens in the case of gases.
Hence, a sponge is solid though it is compressible.
