Description of experiment
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Needed compounds:
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sodium dithionite : Na2S2O4 . 2H2O
potassium ferrocyanide : K4 [Fe(CN)6] . 3H2O
ferric chloride : FeCl3 . 6H2O
Class:
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elem=Fe
coordination
redox
Summary:
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Dithionite is capable of reducing prussian blue (ferric ferro cyanide).
Description:
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Add a solution of ferric chloride to a solution of potassium ferro cyanide:
A dark blue precipitate is formed. This is the well known prussian blue.
Add a freshly prepared solution of sodium dithionite: The dark blue precipitate
disappears. The liquid becomes a little bit milky and gets a pale yellow color.
A strong smell of sulphur dioxide and possible hydrogen sulfide is observed,
the dithionite decomposes quickly.