[dastgir]

Dear Sir,

Why some soln. prepared as molar(M) soln. while others are as normal(N).

Is there any rule behind this?

Why in complexometric titratin EDTA is generally prepared as molar soln?

Faithfully Yours,
Gulam Dastgir

[Borek]

Is there any rule behind this?

No.

Why in complexometric titratin EDTA is generally prepared as molar soln?

Doesn't matter - in the case of EDTA (used as chelating agent) normality=molarity.

[dastgir]

Dear Borek,

How can be molarity of EDTA can be same when we titrating it with two different cations e.g. Ca(2+)
and Al(3+).

Regards,

Gulam Dastgir

[Borek]

You are asking about normality, not molarity.

This is the specific of the chelating agents - they react with metals 1:1.

[dastgir]

Dear Borek,

Sorry borak, Yes i meant normality.

Are all chelating agent react with metal in 1:1 ration or there is any exception?

Is this rule is for only chelating agents or for complexing agent?

Regards,

Gulam Dastgir

[Borek]

Are all chelating agent react with metal in 1:1 ration or there is any exception?

Basicaly chelating agents serve as several ligands at the same time. It doesn't mean they have to react 1:1 with metal. EDTA is s chelating agent and reacts 1:1, ethylenediamine is a chelating agent, but it doesn' have to react 1:1.

Is this rule is for only chelating agents or for complexing agent?

1:1? Only for SOME chelating agents.