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?