Question

The colour change of crystal violet in non-aqueous titration in acidic medium is _______

• A. \( \text{Violet} \)
• B. \( \text{Orange} \)
• C. \( \text{Yellowish green} \)
• D. \( \text{Pink} \)

Hint:

Think of crystal violet's color change like a traffic light in reverse for acid titration: starts blue/violet (go), turns green/yellow (slow down), then the endpoint.

Answer 1

The Correct Option is C

Crystal violet is a visual indicator commonly used in non-aqueous titrations, particularly for titrating weak bases with a strong acid titrant (e.g., perchloric acid) in a non-aqueous solvent like glacial acetic acid. In a strongly acidic medium, crystal violet exists in its yellow form (or sometimes described as yellowish-green). As the titration proceeds and the solution becomes less acidic (approaching the equivalence point), the color changes to blue-violet and finally to green at the endpoint. Therefore, the color change in an acidic medium is from violet (basic or neutral form) to yellowish green (acidic form).