InterviewSolution
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InterviewSolution
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The acid from of an acid base indicator is yellow in acid and red in basic from. What is the change in `pH` in order to change the indicator form `80%` yellow to `80%` red. |
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Answer» Correct Answer - A::B `{:(,HInhArr,H^(o+)+,Ind^(Theta),),(,"Acid form",,"Base form",),("First case:",80%"yellow",,20%red,),("Second case:",20%yellow,,80%red,):}` First case: a. `pH_(1) = pK_(a) + "log" ([In^(Theta)])/(["Hin"])` `= pK_(a) + log ((20)/(80)) …(i)` ` = pK_(a) + log 1//4` Second case: b. `pH_(2) = pK_(a) + log ((80)/(20))` `= pk_(a) + log 4 ...(ii)` From equations (i) and (ii), we get `pH_(2) - pH_(1) = 2 log 4 = 4 log 2 = 4 xx 0.3 = 1.2` |
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