[idest]

In an experiment, I should find the concentration of silver acetate.
I make a solution including water, silver acetate, and ferric alum solution.
Ferric alum solution is made by dissolving ferric alum in water.
Ferric alum has Fe³⁺ ion, so I use KSCN as titrant.
Fe³⁺ reacts with SCN^- to give red colored compound, Fe(SCN)²⁺, so it plays a role as an indicator.

Fe³⁺(aq) + SCN^-(aq)  Fe(SCN)²⁺(aq)

However, my book doesn't provide the detail of reactions between Ag⁺ and the titrant.
So I have to think about the process of reaction myself. (1)Please check if these are correct, or not.
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I think that red color is shown when a reaction including Ag+ is over. If otherwise, I can't get the concentration.
Therefore, there are two possibilities:
1. Ag⁺ reacts with SCN^- preferentially (and then Fe³⁺) to give AgSCN whose solubility is 0.00021 g/L i.e. insoluble in water.

Ag⁺(aq) + SCN^-(aq)  AgSCN(s)

2. Ag⁺ reacts with Fe(SCN)²⁺ whatever reactions like a substitution.
However, Fe³⁺ is kind of indicator, so it'll be made not to be in reaction directly when designing an experiment.
And I've never seen the exchange of metal ions (not ligands) in complex ions. (If you know examples, please tell me.)
Because of aforementioned reasons, I conclude 1st one is correct.
(2)If this is true, Why does the precipitation of Ag⁺ occur earlier than formation of Fe(SCN)²⁺?
(3)Or maybe does other reactions occur with Ag⁺?
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Additional question)
If you know good books that include details of organic compounds and inorganic compounds, please recommend them respectively.

Thanks.

[Borek]

As long as Ag⁺ is present in the solution addition of SCN^- means precipitation of AgSCN, so there is no free SCN^- and no FeSCN²⁺ is created. It is excess SCN^- that reacts with Fe³⁺ creating visual effect.

It is a matter of the values of Ksp of AgSCN and Kf of FeSCN²⁺ - other values of the constants and it would be impossible to use these two reactions together.

[idest]

Oh, Thank you. I've got it!