1.

When the diluition increases by 100 times, the dissociation increases by 10 times.Justify that statement.

Answer»

Solution :(i) Let us consider an acid with `K_a` value `4 times 10^-14`. We are calculating the degree of dissociation of that acid at two different CONCENTRATION `1 times 10^-2 M` and `1 times 10^-14`M using Ostwaid.s dilution law.
`a=sqrt(K_a/C)`
(ii) For `1 times 10^-2 M` acid `a=sqrt((4 times 10^-4)/(1 times 10^-2))=sqrt(4 times 10^-2)=2 times 10^-1=0.2`
(III) For `1 times 10^-4 M` acid `a=sqrt((4 times 10^-4)/(1 times 10^-4))=sqrt4=2`
(iv) i.e., when the dilution increases by 100 times (concentration decreases from `1 times 10^-2M` to `1 times 10^-4M`) the dissociation increases by 10 times.
(v) When dilution increases, the degree of dissociation of weak electrolyte also INCREASE, (Ostwalsd.s dilution law).


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