Question

I have a question about titration. When the indicator (usually a WA or WB) changes color,what is the state of the indicator itself? i.e. if titrant = Strong Acid, titrand = Strong base. If the indicator is a weak acid, at the equivalence point is the indicator itself neutral? Protonated? Deprotonated?

Answer 1

actually, u cannot maintain the equivalance point of the solution that is Ph = 7 during totration. After nutalization point with small amount addition of acid into base (or base into acid), the pH value change drastically and increases for small amount of acid addition as well as decreases for small amount of base addition. and the suitable indicator should change in colur by changing its state (either protonated at lower pH or deprotonated at higher pH).

At a low pH, a weak acid indicator almost entirely in the protonated form and after nutralization point it become gradually deprotonated.