Assume an indicator works best when the equivalence point of a titration comes in the middle of the indicator range.Which indicator would be best for the following titration? 0.100 M HOCl (K_a = 3.5 $\times$ 10^-⁸)+ 0.100 M NaOH

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Quizplus · Accepted Answer

The titration involves a strong base (NaOH) and a weak acid (HOCl). The equivalence point of the titration will occur when all of the HOCl has been converted to the conjugate base, OCl-. At this point, the solution will be basic. Thymolphthalein is a suitable indicator for this titration because its pH range (9.5 - 10.5) is close to the expected pH at the equivalence point (pH ~10). The indicator will change color as the solution becomes basic, indicating the end of the titration.

Assume an Indicator Works Best When the Equivalence Point of a Titration