(a) Give two characteristic features of boiling (b) What will be the effect of the following on the boiling point of water: (i) addition of crystals of sodium chloride, (ii) reduction of the atmospheric pressure? (c) State two ways in which boiling differs from evaporation.
Explanation
(a) The vapour pressure must be equal to the atmospheric pressure. Bubbles of the vapour are formed at boiling. (b)(i) Addition of crystals of sodium chloride will increase the boiling point of water. (ii) Reduction of the atmospheric pressure will lower the boiling point of water (c) Boiling accurs at a constant temperature while evaporation occurs at every given point of temperature rise. Boiling occurs when the vapour pressure of the pure liquid equals the atmospheric pressure while evaporation has no bearing with the atmospheric pressure.
