Explain solubility of solution formed by gaseoius solute and liquid solvent.

Explanation

Solubility of a gas is maximum amount gaseous solute that can be dissolved in a specified amount of solvent at a specified temperature and pressure.
Oxygen dissolves only to a small extent in water. It is this dissolved oxygen which sustains all aquatic life. On the other hand, hydrogen chloride gas (HCl) is highly soluble in water. Solubility of gases in liquids is greatly affected by pressure and temperature.

Effect of pressure on the solubility of a gas.
The concentration of dissolved gas is proportional to the pressure on the gas above the solution.
(i) Effect of pressure : The solubility of gases increase with increases of pressure. For solution of gases in a solvent, consider a system as shown in Fig. (a). The lower part is solution and the upper part is gaseous system at pressure P and temperature T. Assume this system to be in a state of dynamic equilibrium, i.e., under these conditions rate of gaseous particles entering and leaving the solution phase is the same. Now increase the pressure over the solution phase by compressing the gas to a smaller volume [Fig. (b)]. This will increase the number of aseous particles per unit volume over the solution and also the rate at which the gaseous particles are striking the surface of solution to enter it. The solubility of the gas will increase untill a new equilibrium is reached resulting in an increase in the pressure of a gas above the solution and thus its solubility increases.
(ii) Effect of temperature : Solubility of gases in liquid decreases with increase in temperature. When gases are dissolves at that time they are in liquid phase and phenomenon of dissolution is called condensation. In this reaction heat produces. Dissolution process is exothermic in nature so on increase in temperature solubility decreases.