The rapid change of `pH` near the stoichiometric point of an acid-base titration is the basic of indicator detection. `pH` of the solution is related to the ratio of the concentration of conjugate acid `(Hin)` and base `(In^(-))` forms of the indicator by the expression

Options

A. `log . ([ln^(-)])/([Hln])=pH-pK_(ln)`
B. `log . ([ln^(-)])/([Hln])=pK_(ln)-pH`
C. `log. ([Hln])/([ln^(-)])=pK_(ln)-pH`
D. `log.([Hln])/([ln^(-)])=pH=pK_(ln)`

Answer

A

Explanation

`Hln hArr H^(+) +ln^(-)`
`K_(ln)=([H^(+)][ln^(-)])/([Hln])`
`-logK_(ln)=-log[H^(+)]-log.([ln^(-)])/([Hln])`
`pK_(ln)=pK_(a)-log.([ln^(-)])/([Hln])`
`log.([ln])/([Hln])=pH-pK_(ln)`