Question

Dissolution of a non-volatile solute into a liquid leads to:
(A) a decrease of entropy
(B) an increase in tendency of the liquid to freeze
(C) an increase in tendency to pass into the vapour phase
(D) a decrease in tendency of the liquid to freeze

Answer 1

Hint:This question is based on the concept of molal depression constant, or we can say that the freezing point depression. We have to relate the freezing point depression to the non-volatile solutes.

Complete step by step solution:First, we will know about the freezing point of liquid. > When the liquid, and solid state exists in the equilibrium that temperature is defined as the freezing point of the liquid.
> In the other terms, when the solid, and liquid state have the same vapour pressure, that temperature is also known as the freezing point of liquid.
> When we dissolve non-electrolyte, non-volatile in pure solvent; the vapour pressure of the solvent is lowered.
> Now, we can say that the non-volatile solute containing the solution has greater entropy than the pure liquid.
> So, the non-volatile solution will have less tendency to freeze.
> Thus, we can say that there is a decrease in freezing point of solution on the addition of non-volatile solutes.
> In the last, we can conclude that the dissolution of a non-volatile solute into a liquid leads to a decrease in tendency of the liquid to freeze.
Hence, the correct option is (D).

Note: Don’t get confused while defining the non-volatile solute in consideration with the freezing point, as the decrease in vapour pressure leads to the decrease in freezing point of a solution in terms of non-electrolyte. In case of pure liquids, it is dependable on the number of dissolved non-volatile solute particles.