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State Ostwald’s dilution law. |
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Answer» Solution :The dissociation of acetic ACID can be represented as `CH_3COOH HARR H^+ +CH_3 COO^-` The dissociation constant of acetic acids is `k_(a)=([H^+][CH_3 COO^(-)])/([CH_3 COOH])""…(1)`  Substituting the equilibrium concentration in equation (1) `k_(a)=((alpha C)(alpha C))/((1-alpha)C)` `k_(a)=(alpha^2 C)/(1-alpha)""...(2)` We know that WEAK acid dissociates only to a very small extent compared to ONE `alpha` is so small and HENCE in the denominator `(1-alpha) ~=1`. The above expression (2) now becomes. `k_(a)=alpha^2 C` `rArr alpha^2 =(K_(a))/(C ) ` `alpha=sqrt((K_a)/(C ))` |
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