Question

Ostwald's dilution law is applicable in the case of the solution of:
A. $NaCl$
B. $NaOH$
C. ${H_2}S{O_4}$
D. $C{H_3}COOH$

Answer 1

Hint – Ostwald's dilution law determines the dissociation constant of the weak electrolyte with the degree of dissociation and the concentration of the weak electrolyte. Thus the law holds good only for weak electrolytes.

Complete step-by-step answer:
Let us understand first what strong and weak electrolytes are.
So before classifying electrolytes as strong and weak let us see what an electrolyte is: An electrolyte is a substance which when dissolved in water breaks or dissociates into anions (positively charged ions) and anions (negatively charged ions) respectively.
A strong electrolyte is a good conductor of electricity and completely dissociates or ionizes in a solution i.e. 100% ionization, whereas a weak electrolyte is a poor conductor of electricity due to the fact that it dissociates only partially i.e. ionization of the order 1-10%.
The Ostwald’s dilution law as stated earlier, holds good only for weak electrolytes.
The Arrhenius theory of electrolyte dislocation explains that the molecules of an electrolyte in a solution are continuously breaking up into ions and the ions are constantly associating to form unionized molecules. Thus, a dynamic equilibrium exists between ions and unionized molecules of the electrolyte in that solution. Later it was noticed by Ostwald that just as chemical equilibrium, the law of mass action can be applied to such systems as well.
Since the law holds good only for weak electrolytes, and the only weak electrolyte in the question is $C{H_3}COOH$. So, option D is correct.

Note: Ostwald's dilution law serves a well and adequate description of the concentration dependence of the conductivity of weak electrolytes like $C{H_3}COOH$ and $N{H_4}OH$. The difference in the molar conductivities is due to the fact that the weak electrolytes do not dissociate completely into ions.