I have done an experiment in the lab at school and I have to write a report. The goal was to determine whether or not a wine (white) was contaminated
with iron phosphate (II) or (III).
Since we were using a colorimeter to evaluate the quantity of iron in solution, we first had to convert al the iron(II) phosphate to iron(III)
phosphate using H2O2 in HCl. We then added KSCN to precipitate red thiocyanatoiron ion which is what is tested for with the colorimeter.
I'm guessing the reaction is as follows but I can't figure what happens to the chloride and the phosphate ions:
2Fe2+ + 2H+ + H2O2 --> 2Fe3+ + 2H2O
6FePO4 + 6HCl + 3H2O2 --> 2Fe3(PO4)2 + 6H2O
In the reaction to make ferric chloride from ferrous chloride (similar to this reaction), the chloride from the HCl is used by the iron but in this
reaction I don't understand what happens to it.
Maybe the reaction produces a mixture of iron(III) chloride and phosphate?
Thanks in advance for your replies,
R.DraconicAcid - 27-2-2014 at 09:09
The chloride and phosphate ions are basically hanging around in solution, not really caring about the iron ions. If you evaporated it to dryness, you
would have a mixture of iron(III) chloride and iron(III) phosphate.
When you add thiocyanate, you form thiocyanatoiron(III) ion, but you don't precipitate it- it stays in solution. Romain - 27-2-2014 at 11:11
So the reaction would be:
2Fe2+ + 2H+ + H2O2 --> 2Fe3+ + 2H2O?
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