Question

In a complexometric titration of metal ion with ligand $M($ Metal ion $)+L($ Ligand $)\to C($ Complex $)$ end point is estimated spectrophotometrically (through light absorption). If 'M' and 'C' do not absorb light and only 'L' absorbs, then the titration plot between absorbed light ( $A$ ) versus volume of ligand 'L' $(V)$ would look like

• A.
• B.
• C.
• D.

Answer 1

Answer: (B)

Ligand concentration is maximum when the reaction has not been initiated.

At that point, absorption of light by ligands will be maximum.

As the reaction starts, ligand concentration decreases so is the absorption of light till the point where all the metal ions are consumed and further complex formation does not take place.