How much water must be added to `300 mL` of a `0.2M` solution of `CH_(3)COOH` for the degree of dissociation of the acid to double ? ( Assume `K_(a)` of acetic is of order of `10^(-5)M)`

Options

A. `900 ml`
B. `300ml`
C. `600 ml`
D. `1200ml`

Answer

1

Explanation

Initially degree of dissociation `alpha=sqrt((K_(a))/(C))`
Now degree of dissociation, `alpha_(1)=2alpha=sqrt((4K_(a))/(C))=sqrt((K_(a))/(C_(1)))`
so `" "C_(1)=(C)/(4)" "rArr" "` Hence we have
`300xx0.2rArrV_(1)xx(0.2)/(4)" "`so `V_(f)=1200ml`
Hence water added `=1200-300=900ml`