Description of experiment
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Needed compounds:
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potassium iodate : KIO3
chrome alum : KCr(SO4)2 . 12H2O
Class:
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elem=Cr,I
precipitation
coordination
Summary:
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Chromium(III) ions give a light green precipitate with iodate.
Description:
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Dissolve some solid chromium sulfate (or chrome alum) in some water: A fairly
dark, pruple/blue/grey solution is obtained (somewhat hard to describe color).
Dissolve some potassium iodate in water: A colorless clear solution is
obtained. It takes some time to dissolve all of the solid, it does not dissolve
easily.
Add the solutions to each other, assuring that an excess amount of iodate is
used: A remarkably light precipitate is produced. The precipitate has a nice
light green/mint color.
Heat the solution: The precipitate becomes more coarse, it remains light green.