Question

A student is visually impaired, which one of the following indicator you will suggest him for the acid base titration?

• A. Litmus
• B. Turmeric
• C. Vanilla
• D. Petunia

Hint:

Olfactory indicators like vanilla essence, clove oil, and onion paste are useful in laboratory experiments designed for visually impaired students.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Chemical indicators are used in titrations to signal the endpoint of a reaction.
- Visual Indicators: Change color when the pH of the solution changes (e.g., litmus, turmeric).
- Olfactory Indicators: Change their odor or smell in response to changes in pH.

Step 2: Detailed Explanation:
A visually impaired student cannot use visual indicators to identify when a color change occurs.
Therefore, they must rely on olfactory indicators, which change their smell based on whether the solution is acidic or basic.
Let us analyze the options:
- Option (A) Litmus: A visual indicator that turns red in acid and blue in base.
- Option (B) Turmeric: A natural visual indicator that remains yellow in acid and turns reddish-brown in base.
- Option (C) Vanilla: An olfactory indicator. It has a characteristic sweet smell that is retained in acidic solutions but disappears in basic solutions. The student can identify the endpoint of the titration by noting when the vanilla odor is no longer present.
- Option (D) Petunia: A flower extract that acts as a visual pH indicator.

Step 3: Final Answer:
The correct option is (C).