Question

Which of the following are correct regarding complexometric titration?
A. A titration in which color is changed due to the formation of complex
B. Usually occur when d-block elements are involved
C. Usually happen when chelating ligands are involved
D. All of the above.

Answer 1

Hint:As we know that titration is a technique in which we can find the concentration of an unknown solution with the help of another solution of known concentration. As from the name, the complex will be formed in complexometric titration.

Complete answer:
In this titration, the complex formed will be colored which indicates the end point of titration. When a metal ion is reacted with an anion or a neutral molecule, complexes are formed. The mixture of different metal ions can be determined using complexometric titrations. The complex involves a central metal atom and anion or neutral molecule which is called the ligand. The central metal atom is bonded with the ligand using coordinate bond.
Coordinate bond is formed when the electron pairs are donated from a single atom. There are different types of ligands. They are unidentate, bidentate, polydentate and ambidentate ligands. When polydentate ligands are bonded with metal, it forms a complex called chelate. The ligands are called chelate ligands. Complexometric titration is a type of volumetric analysis. Another term used for complexometric titration is chelatometry. This usually occurred in the presence of d-block elements.
So all the given statements are correct.

Hence the correct option is D.

Note:
The indicators are used to indicate the end point. It changes its color to indicate the completion of the reaction or titration. Some indicators are EBT, curcumin, hematoxylin etc. A common example of complexometric titration that all of us have done is titration of EDTA. This is done to measure the hardness of water.