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What are the indicators for each type of acid-base titration?
Posted October 10, 2023

Answer

Acid-base indicators are classified into 3 different groups: phthaleins and sulphophthaleins, azo indicators, and triphenylmethane indicators. The two most common indicators used in acid-base titration are phenolphthalein and methyl orange. Phenolphthalein can be used for strong acid-strong base titrations as well as weak acid-strong base titrations. Methyl orange can be used for strong acid-weak base titration. For weak acid-weak base, there is no indicator that is suitable for this titration.

Examples of indicators for each type of titration:

  • Bromothymol blue and phenol red can be used for strong acid-strong base titrations.
  • Cresol red or thymol blue can be used for strong acid-weak base titrations.
  • Thymol blue can also be used for weak acid-strong base titrations.