Question

The ionization constant of chloroacetic acid is `1.35xx10^(-3)`. What will be the `pH` of `0.1 M` acid and its `0.1M` sodium salt solution?

Answer 1

i. pH of acid solution: It is `W_(A)`
`pH_(W_(A))=1/2(pK_(a)-logC)`
`=1/2(2.86-log 0.1)=1.93`
ii. `K_(a)=1.35.5 10^(-3) pK_(a)=2.86`
Sodium acetate is a salt of `W_(A)//S_(B)`.
`pH=1/2 (pK_(w)+pK_(a)+log C)`
`=1/2(14+2.86+log 0.1)`
`=1/2(16.86-1)=7.94`