Question

Which of the following titrations cannot be carried out using Phenolpthalein ?

1 point

Sodium Hydroxide vs. Hydrochloric acid

Sodium Bicarbonate vs. Sulphuric acid

Ammonium hydroxide vs. oxalic acid

Calcium Hydroxide vs. Nitric acid.​

Answer 1

Answer:-

HCl and NH4(OH)

EXPLANAION:-

The equivalence point of a titration is where you have mixed the two substances in exactly equation proportions. You obviously need to choose an indicator which changes colour as close as possible to that equivalence point. That varies from titration to titration. Phenolphthalein indicator distinguishes the pH change between pH 8 to 10. Therefore it is used for strong acid and strong base titrations or weak acid and strong base titrations. In the given options, HCl and NH

4OH is a strong acid and weak base titration where phenolphthalein is useless as an indicator.

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