[Icanfly]

Hello everyone,

I tried to do the following exercise but I have not be able to answer  to the 4) question. Someone have an idea please?

We want to synthesize Fe₃O₄:

1) What are the cations present in Fe₃O₄ and what is their proportion?
This is my answer: we have Fe²⁺ and Fe³⁺ more exactly 2 Fe³⁺ and 1Fe²⁺

2)What is the hydrolyse balance of (Fe(H₂O)₆)^z+ for the different cations?

(Fe(H₂O)6)²⁺    + H₂O = (FeO₆H₁₁)⁺  + H₂O
(Fe(H₂O)6)³⁺   + H₂O = (FeO₆H₁₁)²⁺  + H₂O

3)Calcul the pH for h=1,2 and 3

For (Fe(H₂O)₆)⁺²: pH=4,3( h=1), pH=7,1( h=2) and pH=10,2(h=3)

For (Fe(H₂O)6₆)³⁺: pH=0,9( h=1), pH=3,5( h=2) et pH=6,3( h=3)

4)Which complexe can allow you to obtain Fe₃O₄ by condensation mechanism in aqueous solution?