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Topic: how to make pure Fe(OH)2?  (Read 9123 times)

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bindy

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how to make pure Fe(OH)2?
« on: December 04, 2004, 03:14:06 AM »
my chemistry teacher has asked us to come up with a modified equipment to make pure Fe(OH)2.
It is viable that we use boiled water with plant oil on top.But because of its properties its soon oxided anyways.i came up an idea that might be feasible but she said it wasnt good one.But i think it can ensure purity of Fe(OH)2 pretty well.So whats the problem of it?And if you have better idea as to making of Fe(OH)2,and if you share it with me,i would much appreciate it.
My practice:
1.inject into test tube FeI2 sollution,which is made with vapored water.(Instead of other iron(II)salt coz i need iodine ions later on).
2.pure into test tube a reasonable amount of tetrachloromethane,and it sinks to the bottom.
3.Drip in NaOH

As we can see,I- ions remain in the solution as Fe(OH)2 forms.The white powder formed soon turn gray-green a bit,but Fe(III) as a relatively strong oxidant will oxidize I-,while reducing itself back to Fe(II).I2 generated will solute in CCl4,and that makes Fe(OH)2 generally pure.For better results,you can add a seal to the testtube but as long as there is I- in the solution Fe(II)is well protected.This is just like putting an iron pit into Fe2+ solution to keep it from oxidized.Why isnt it working?

Offline kevins

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Re:how to make pure Fe(OH)2?
« Reply #1 on: December 24, 2004, 01:50:38 AM »
I think you use FeI2 is not a suitable reagent because iodine is an oxidizing agent. Although you use the CCl4 to extract the iodine, it take an equilibrium with the aqueous phase.
I suggest you use pure ammonium iron (II) sulphate and also keep the solution in the reducing atmosphere by some reducing agent such as sodium sulphite, hydrazine etc.
Please try. :D

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