[AhmedEzatAlzawalaty]

Why metal EDTA complex should be stronger than Metal-Indicator complex in titration?

[AhmedEzatAlzawalaty]

is it difficult or what?

[lft123]

else metal will complex first with indicator instead of EDTA !

[ARGOS++]

Dear AhmedEzatAlzawalaty,

(Really nice to have you back again!)

To understand the problem you have to think in a little different way.
Complexometric reactions are NOT absolute reactions; they are “balanced” reactions as so many other.

So both reaction constants together including all concentrations will tell you how much EDTA complex and how much Indicator complex exist at the same time.

If you now put in account, above which threshold you will recognise the colour of the Indicator complex, you can easily estimate the influence of the different stability constants (reaction constants) to your result. 

I hope it may be of help to you!

Good Luck!
                    ARGOS⁺⁺