Question

The ratio of dissociaiton constant of two weak acids `HA` and `HB` is `4:1` .AT what initial molar concentration ratio of two acid solution,the two will have same `pH` in separate solutions.Assume negligible association of both acids in their solutions.
A. `2:1`
B. `1:2`
C. `4:1`
D. `1:4`

Answer 1

`K_(a)=([H^(+)][A^(-)])/([HA])=([H^(+)]^(2))/([HA])( :.[H^(+)]=[A^(-)])`
and `K_(b)=([H^(+)][B^(-)])/([HB])=([H^(+)])^(2)/([HB])( :.[H^(+)]=[B^(+)])` Also `H^(+)` are same `:.(K_(a))/(K_(b))=([HB])/([HA])=(4)/(1) ([HA])/([HB])=(1)/(4)`