Question

At equilibrium, the rate of dissolution of a solid in a volatile liquid solvent is:
A. less than the rate of crystallisation
B. greater the rate of crystallisation
C. equal to the rate of crystallisation
D. zero

Answer 1

Hint: When condition is given as equilibrium, this means that in the reaction the reactants are being converted to products, and products are being converted to reactants both at the same speed. And it is found that there is no net change in concentration of both reactants and products.

Complete Solution :
- We know that at equilibrium, the rate of forward reaction is equal to rate of backward reaction.
- In this case of equilibrium, the forward reaction will be dissolution, because we are dissolving it. And the backward reaction of dissolution will be crystallisation, as we are dissolving a solid solute, which will again become in crystallise form.
So, the correct answer is “Option C”.

Additional information: - As we know that solubility is the property of any matter by which it helps them to dissolve in solvent. And there are various factors that affect the solubility, some of them are:
- Pressure – It is found that with the increase in pressure of the gas, the solubility property is said to increase.
- Temperature- With the increase in the temperature of the solvent, the solubility is found to decline.

Note: -We must know the condition of equilibrium for this case, the rate of forward reaction is equal to rate of backward reaction.
- The result of this is equilibrium is found that the concentration of the reactants and products do not change.
- It is found that when a solution is saturated and excess solute is present, then the rate of dissolution is equal to the rate of crystallisation.