InterviewSolution
Saved Bookmarks
InterviewSolution
| 1. |
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 expressionA. `log.([In^(-)])/([HIn])=pK_(In)-pH`B. `log.([HIn])/([In^(-)])=pK_(In)-pH`C. `log.([HIn])/([In^(-)])=pH-pK_(In)`D. `log.([In^(-)])/([HIn])=pH-pK_(In)` |
|
Answer» Correct Answer - D Acid indicatiors are generally weak acid. The dissociation of indicator Hin takes place as floows `HIn hArr H^(+)+In^(-)` `therefore K_(In)=([H^(+)][In^(-)])/([HIn])` or `[H^(+)]=K_(In).([HIn])/([In^(-)])` ….(i) `because pH=-log [H^(+)]` ...(ii) From eq. (i) and (ii) we get, `therefore pH=-log(K_(In).([HIn])/([In^(-)]))` `=-log K_(In)+log.([In^(-)])/([HIn])=pK_(In)+log.([In^(-)])/([HIn])` or `log.([In^(-)])/([HIn])=pH-pK_(In)` |
|