Question

The best indicator for detection of end point in titration of a weak acid and a strong base is:

• A. methyl orange (3 to 4)
• B. methyl red (5 to 6)
• C. bromothymol blue (6 to 7.5)
• D. phenolphthalein (8 to 9.6)

Answer 1

The correct option is D phenolphthalein (8 to 9.6)

The pH of the solution at the equivalence point will be greater than 7 due to salt hydrolysis. So an indicator giving colour in basic medium will be suitable.
Phenolphthalein is a good indicator if the base is strong because strong base immediately changes the pH at end point.