Question

What is the effect of temperature on solubility of a gas?
(A) Solubility of a gas increase with rise in temperature
(B) Solubility of a gas decreases with rise in temperature
(C) No effect
(D) Sometimes increases with increase in temperature, sometimes decreases

Answer 1

Hint: Whenever we are given the pressure and temperature, Charle’s law must strike to your mind. It states that the volume of a given mass of gas dissolved in a solution is directly proportional to the change in temperature.

Complete step-by-step answer:
Solubility is defined as the maximum quantity of solute that can dissolve in a certain quantity of solvent or solution at a specific temperature. For gases, the solubility decreases as the temperature increases. This happens because when most gases dissolve in solution, the process becomes exothermic. This states that heat is released when the gas is dissolved.
It is similar to the increase in vapour pressure with rise in temperature which causes rise in kinetic energy. The higher the kinetic energy, the more rapidly the gas molecules will move which will break the intermolecular bonds and escape from solution.
Le Chatelier’s principle can also explain the effect of temperature on solubility. It states that if a stress is applied to an equilibrium, the system adjusts accordingly to minimize the stress. This means how much a system will respond to a change in external conditions provided.
According to it, the solubility increases with an increase in temperature if the process is endothermic. If it is an exothermic process, temperature rise will decrease the solubility by shifting the equilibrium.
Charle’s law states that the volume of a given mass of gas dissolved in a solution is directly proportional to the change in temperature at constant pressure. Therefore, solubility of a gas decreases with rise in temperature.

Hence, the correct option is (B).

Note: This can also be described by Henry’s law. If there is a rise in temperature, its kinetic energy will increase and bonds will break resulting in escape of molecules from the solution. The gases thus start dissolving rapidly and hence the solubility of gases decrease.