Question

The solubility of gases in water _________ with rise in temperature.
[A] Increases
[B] Decreases
[C] No change
[D] None of the above

Answer 1

Hint: Solubility of a gas is basically the property of gas particles to be dissolved in liquid. It is affected by pressure and temperature. To answer this, approach considering the kinetic theory of gases. Think about how temperature affects the movement of gas molecules.

Complete step by step answer:
We know that solubility of a solute is a property of it getting dissolved in a solution generally aqueous solution i.e. water. This property can be exhibited by chemical compounds in any state i.e. solid, liquid or gaseous.
Solubility of a substance can depend upon temperature, pressure and surface area depending upon whether the solute is a solid, liquid or gas.
Now, let us see the meaning of solubility of gases.
Solubility of gas basically means dissolving of a gas in a liquid. We can carry this out by changing the pressure. The change in solubility of a gas upon changing pressure is given by Henry’s law.
Henry’s law states that the solubility of any gas in a liquid is proportional to the partial pressure of the gas above the liquid at a given temperature.
However, solubility of a gas in a liquid does not depend just on the pressure, it also varies with temperature.
When we increase the temperature, the kinetic energy of the gas particles increases and thus they move faster which results in them escaping the liquid. Thus, the solubility decreases with increasing temperature. Lower the temperature, higher will be the solubility.
From the above discussion we can understand that the solubility of gases in water decreases with increase in temperature.
So, the correct answer is “Option B”.

Note: The two factors that we discussed above, among them only temperature affects the solubility of a liquid. Solubility of a liquid is not directly affected by pressure. Surface area also does not affect the solubility directly. However, surface area is the factor due to which the amount of solvents getting dissolved varies.