Question

In the complexometric titration of metal ion with ligand
M(Metal ion) + L (Ligand) → C (complex) end point is estimated spectrometrically (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 like:
(A)

(B)

(C)

(D)

Answer 1

Hint: As we that the volumetric titrations or analysis during which the end point is indicated by a coloured complex, are referred to as complexometric titrations. Now we will discuss the formation of complexometric titration of metal ions with ligand.

Complete step by step answer:
We must remember that complexometric titrations are used for determination of concentration of metal ions within the solution. During this sort of titration an indicator is employed which is capable of manufacturing clear colour change in titration which indicates end point of titration.
As we’ve the concentration changes in equilibrium,
\[A + B \rightleftharpoons C + D\]
With passage of time, there is accumulation of the products C and D and depletion of A and B eventually the two reactions occur at same time.
Initially ligand consumed by metal thanks to formation of complex, so absorbed light(A) remains constant, after complex formation is completed. Extra volume of ligand solution increases ligand concentration and also increases absorbed light.
In case of option A, the volume goes on increase. Therefore, the option A is incorrect.
In case of option B, volume remains constant. Therefore, the option B is correct.
In option C, the volume increases gradually. Therefore, the option C is incorrect.
In case of option D, the volume decreases. Therefore, the option D is incorrect.

Therefore, the correct option is B. .

Note: As we know complexometric indicator is an ion chrome dye that undergoes definite color change in presence of specific metal ions. It forms a weak complex with the ions present within the solution, which has a significantly different color form from the prevailing outside the complex.