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What would be a good indicator to use for a titration of a weak acid with a strong base?

A) methyl red (4.4 - 6.2)
B) phenolphthalein (8.2 - 10)
C) bromthymol blue (6.0 - 7.6)

User Greengold
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1 Answer

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Final answer:

For the titration of a weak acid with a strong base, the indicator that should be used is phenolphthalein.

Step-by-step explanation:

In general, for titrations of strong acids with strong bases (and vice versa), any indicator with a pKin between about 4.0 and 10.0 will do. For the titration of a weak acid, however, the pH at the equivalence point is greater than 7.0, so an indicator such as phenolphthalein or thymol blue, with pKin > 7.0, should be used. Conversely, for the titration of a weak base, where the pH at the equivalence point is less than 7.0, an indicator such as methyl red or bromocresol blue, with pKin < 7.0, should be used.

User Pablo Cabrera
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