Description of experiment
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Needed compounds:
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potassium ferrocyanide : K4 [Fe(CN)6] . 3H2O
ferrous sulfate : FeSO4 . 7H2O
sodium sulfite hepta hydrate : Na2SO3 . 7H2O
sodium bisulfate : NaHSO4
Class:
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elem=Fe
precipitation
coordination
Summary:
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Reaction between ferrous-ion and hexacyanoferrate (II) ion.
Description:
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Dissolve some NaHSO4 and Na2SO3.7H2O in much water and make two portions
of this solution.
To one portion add some ferrous sulfate and dissolve this: The resulting
liquid is essentially colorless. A normal solution of ferrous sulfate
always is pale yellow and a little opaque, due to oxidation and hydrolysis.
The the other portion add some potassium ferrocyanide: The resulting
liquid has a very faint color (almost colorless) and is clear.
Add both portions to each other: The resulting liquid becomes pale blue
and slightly opaque. So still there is some iron (III). Apparently the
ferric ions are bound to the acidic sulfite, such that a pale solution
is created.