Question

Which is used as Fajan's method indicator

• A. Dichlorofluorescein
• B. Methyl red
• C. Phenolphthalein
• D. Xylene orange

Hint:

Dichlorofluorescein acts as an adsorption indicator in Fajan’s method by color change at the precipitate surface.

Answer 1

The Correct Option is A

- Fajan's method is a type of adsorption indicator method used in precipitation titrations, particularly for determining halides by titration with silver nitrate.
- Dichlorofluorescein is commonly used as the indicator in Fajan's method because it adsorbs onto the surface of the precipitate, changing color at the endpoint.
- This color change indicates the completion of the reaction, enabling accurate determination of the endpoint.
- Other indicators like methyl red, phenolphthalein, and xylene orange are used in different types of titrations and are not suitable for Fajan's method.