It has been found that the pH of a 0.01 M solution of an organic acid is 4.15. The concentration of the anion of the acid is :

Options

A. `4.15`
B. `3.85`
C. `7.08xx10^(-5)`
D. `7.08xx10^(-4)`

Answer

C

Explanation

The concentration of `H^(+)` ions is equal to the concentration of the anion.
`[H^(+)]//1M=[A^(-)]//1M=` Anti log `(-pH)`
= anti log `(-4.05)`
`=7.09xx10^(-5)`
`therefore [A^(-)]=[H^(+)]=7.08xx10^(-5)`