Explain what is meant by 'critical phenomenon'? What are 'critical constants' of a gas?
Describe briefly the Isotherm of Carbon dioxide.
Or
Briefly describe the Isotherm of Carbon dioxide as studied by Andrews.
On the basis of kinetic molecular theory of liquids, how can you explain the following properties of liquids:
(i) Volume (ii) Density
(iii) Compressibility (iv) Diffusion?
Explain briefly the factors on which evaporation depends.
Evaporation depends on upon the following factors:
(i) Nature of the liquid. The evaporation depends on the strength of intermolecular forces. The liquids having low intermolecular forces evaporate faster in comparison to the liquids having high intermolecular forces. For example, ether evaporates more quickly than alcohol, and alcohol evaporates more quickly than water. This is because their intermolecular forces of attraction are in the order
Ether < Alcohol < Water
(ii) Surface area. Evaporation is a surface phenomenon. Larger the surface area, greater the opportunity of the molecules to escape. Thus, the rate of evaporation increases with an increase of surface area.
A rate of evaporation ∝ Surface area
(iii) Temperature. The rate of evaporation increases with
the increase of temperature as the kinetic energy of the molecules increases with the rise in temperature.
The rate of evaporation ∝ Temperature
(iv) The flow of air current over the surface. The flow of air helps the molecules to go away from the surface of the liquid and therefore, increases the evaporation.
Explain briefly the term "vapour pressure" . What are the factors on which vapour pressure of a liquid depends?