Question

Why did the colour of phenolphthalein change after the addition of an acid in a basic solution

Answer 1

Answer:

Phenolphthalein is a weak acid, which is why when it is added in a strong base, it gives pink color and the color gets intense as the PH of the base increases.

If a strong acid such as HCL is added in this solution, it with react with base and cause neutralization. By adding HCL in the solution, the pink color of  phenolphthalein will disappear. This is also called Acid- Base Titration.

Answer 2

Answer:

Phenolphthalein is a weak acid, which is why when it is added in a strong base, it gives pink color and the color gets intense as the PH of the base increases. ... By adding HCL in the solution, the pink color of phenolphthalein will disappear.

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