>> Study Material
>> IIT JEE Chemistry
>> Physical Chemistry
>> Solutions of Gases in Liquids
SOLUTIONS OF GASES IN LIQUIDS
All gases are soluble in water as well as in other liquids to a greater or lesser extent. The solubility of a gas in liquids depends upon the following factors:
(i) Nature of the gas
(ii) Nature of the solvent
(iii) Temperature and
Generally, the gases which can be easily liquefied are more soluble in common solvents. For example, CO2 is more soluble than hydrogen or oxygen in water. the gases which are capable of forming ions to aqueous solutions are much more soluble in water than in other solvents. Gases like hydrogen chloride (HCl) and ammonia (NH3) are highly soluble in water but not in organic solvents in which they do not ionize.
The solubility of most gases in liquids decreases with increase of temperature. When a solution of a gas is heated, the gas is usually expelled. However, some gases are more soluble at higher temperature than at lower.
The most important factor which influences the solubility of a gas in liquid is the pressure. the quantitative connection between the solubility and pressure is given by Henry’s law. According to this law, the mass of a gas dissolved by a given volume of a liquid, at constant temperature, is proportional to the pressure of the gas.
Thus, if m be the mass of gas dissolved per unit volume of a solvent and P is the pressure of the gas in equilibrium with the solution, the according to Henry’s law,
m ∞ P at constant temperature
or m = KP where K is proportional constant
or m/P = K
It has been observed that most gases obey Henrys law provided,
(i) The pressure is not too high.
(ii) The temperature is not too low.
The gas is not highly soluble and does not enter into chemical combination with the solvent.