What would be a suitable indicator for the titration of vinegar (0.1 M acetic ac

Question

What would be a suitable indicator for the titration of vinegar (0.1 M acetic acid pKa=4.76)?

A.Crystal Violet

B.Bromophenol blue

C.Methyl orange

D.Bromocresol purple

E.Phenophthalein

F.ThymothaleinA

The answer is pH = 8.74 aka E (Phenolphthalein). Can someone explain me the work to get that answer? Thanks

pH Range 1.0-2.0 1.2-2.8 2.7-4.0 3.0.4.6 3.1-4.4 3.8-5.4 4.2-6.3 5.0-6.4 5.2-6.8 2 6.2-7.6 6.8-8.4 6.8-8.6 8.3-10.0 9.3-10.5 Color Name Crystal Violet Cresol Red Thymol Blue 2,4-Dinitrophenol Bromophenol Blue Methyl Orange Bromocresol Green Methyl Red Eriochrome Black T Bromocresol Purple Bromothymol Blue Phenol Red m-Nitrophenol Phenolphthalein Thymolphthalein

Explanation / Answer

Vinegar is a weak base , so strong base must be added for the titration.When a weak acid is titrated, carefully measured volumes of strong base solution are added to it. In this case, base solution is added until the equivalence point is reached. At this point, enough base has been added to react with all the weak acid present in the sample.when the equivalence point is reached, the pH of the solution will change rapidly, because all the acid has reacted with the added base.so the pH is more than 7. The pH range will be in between 8.3 - 10.0

Therefore the correct indicator for this is phenolphthalein.

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