Question

In complexometric titration _______ is suitable as an indicator.

• A. \( \text{Solochrome black} \)
• B. \( \text{EDTA} \)
• C. \( \text{Phenolphthalein} \)
• D. \( \text{Methylene red} \)

Hint:

Remember "black" in Solochrome black hints at metals, making it a good indicator for complexometric titrations with EDTA.

Answer 1

The Correct Option is A

Complexometric titrations involve the formation of a colored complex between a metal ion and a chelating agent, typically EDTA. Metallochromic indicators are used to detect the endpoint of these titrations by changing color when they bind to or are released from the metal ion. Solochrome black (also known as Eriochrome Black T) is a common metallochromic indicator used in EDTA titrations for determining the concentration of metal ions like calcium, magnesium, and zinc. EDTA itself is the titrant, not an indicator. Phenolphthalein is an indicator used in acid-base titrations, and methylene red is also an acid-base indicator.