What is `[H^(+)]` in `mol//L` of a solution that is `0.20 M` in `CH_(3)COONa` and `0.1 M` in `CH_(3)COOH`? `K_(a)` for `CH_(3)COOH` is `1.8xx10^(-5)`?

Options

A. `3.5xx10^(-4)`
B. `1.1xx10^(-5)`
C. `1.8xx10^(-5)`
D. `9.0xx10^(-6)`

Answer

D

Explanation

`pH=pK_(a)=log`
`(["Conjugate base"])/(["Acid"])`
`=-log1.8x10^(-5)+"log"(0.2)/(0.1)=5.045`
`:. [H^(+)]=9.0x10^(-6)`