Saturday, June 11, 2022

Which indicator is used in the titration of the weak acid-weak base?

Question:-

Which indicator is used in the titration of the weak acid-weak base?
The options are...
  • A. Phenolphthalein
  • B. Methyl orange
  • C. Bromothymol blue
  • D. No indicator is suitable

The correct answer is D: No indicator is suitable for this titration since it requires a vertical portion of the curve over two pH units.


Explanation:

The vertical component of the titration curve when titrating a weak acid with a weak base is so short that it's difficult to find an indicator that will change colors in this small region, therefore a pH meter could be used to determine the endpoint.


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