Question

Ionisation constant of `CH_(3)COOH` is `1.7 xx 10^(-5)` and concentration fo `H^(+)` in certain acetic acid solution is `3.4 xx 10^(-4) M` . The concentration of acetic acid solution is
A. `3.4 xx 10^(-4)`
B. `3.4 xx 10^(-3)`
C. `6.8 xx 10^(-4)`
D. `1.7 xx 10^(-3)`

Answer 1

Correct Answer - A
`CH_(3)COOH hArr CH_(3)COO^(-) +H^(+)`
`K_(a) = [[CH_(3)COO^(-)][H^(+)]]/[[CH_(3)COOH]]`
`[CH_(3)COOH] =[[CH_(3)COO^(-)][H^(+)]]/(K_(a))`
`=(3.4 xx 10^(-4) xx 3.4 xx 10^(-4))/(1.7 xx 10^(-5))`
`=6.8 xx 10^(-4)`