Description of experiment
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Needed compounds:
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sodium persulfate : Na2S2O8
bismuth : Bi
nitric acid : HNO3
Class:
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elem=Bi
redox
Summary:
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Bismuth(III) in nitric acid solutoin is not oxidized by peroxodisulfate to a
bismuth(V) species.
Description:
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Prepare a solution of bismuth nitrate in nitric acid by adding bismuth metal to
nitric acid. Dilute the solution after preparation, such that the acid has a
concentrated between 15 and 20%. If any opalescence appears on dilution
(hydrolysis of bismuth(III) in aqueous non-coordinating solution) then allow
the solid material to settle and decant the clear liquid.
To the clear liquid add some solid sodium peroxodisulfate and carefully heat
the liquid, until all of the solid has dissolved: No reaction occurs. The only
visible reaction is formation of oxygen due to decomposition of peroxodisulfate
when the liquid is heated too strongly.
Allow the liquid to stand for a few hours: After a few hours the liquid still
is clear and colorless, no solid material has settled at the bottom.
Apparently, bismuth(III) is not easily oxidized to bismuth(V) in acidic
solution.