Description of experiment
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Needed compounds:
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sodium metaperiodate : NaIO4
sodium iodate : NaIO3
manganese (II) sulfate : MnSO4 . H2O
Class:
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elem=Mn,I
precipitation
Summary:
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Many iodates are insoluble, but manganese(II) ions do not give a precipitate
with iodate ion, nor is there any redox reaction between these ions.
Periodate on the other hand gives a nice brickred precipitate with
manganese(II).
Description:
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Prepare a solution of manganese(II) sulfate in water. This is an almost
colorless solution.
In two other test tubes prepare
1) a solution of sodium iodate
2) a solution of sodium metaperiodate
Add some of solution (1) to the solution of manganese(II) sulfate: No visible
reaction occurs. The liquid remains clear and colorless. Even when the liquid
is somewhat heated, then no visible reaction occurs.
Add some of solution (2) to the solution of manganese(II) sulfate: Quickly (but
not instantaneously) a red/brown precipitate is formed. The precipitate has a
very fine structure, it is not slimy, but seems to consist of many very fine
crystals. It takes a few seconds before formation of the precipitate is
complete.
First add some of solution (1) and then some of solution (2) to the solution of
manganese(II) sulfate: When solution (1) is added, then no visible reaction
occurs. When some of solution (2) is added, then again a red/brown precipitate
is formed and again it takes a few seconds before the formation of the
precipitate is complete.