Description of experiment
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Needed compounds:
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sulphuric acid : H2SO4
potassium nitrite : KNO2
potassium bromate : KBrO3
Class:
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elem=N,Br
redox
Summary:
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An acidified solution of potassium bromate quickly oxidises solid potassium
nitrite to potassium nitrate, the bromate being converted to bromine.
Description:
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Dissolve some potassium bromate in 20% sulphuric acid and add some solid
potassium nitrite to this solution: The potassium nitrite very quickly
dissolves, giving an orange solution. A few fairly big gas bubbles are produced
at the solid potassium nitrite, but these gas bubbles quickly dissolve in the
liquid. They do not make it to the surface of the liquid, they dissolve before
they reach the surface.
Shake the liquid: Bromine vapor is released into the air above the liquid. A
strong smell of bromine can be observed.
Apparently, no or only a very small amount of nitrogen oxides is produced in
this reaction, the bromate quickly oxidizes the nitrite to nitrate.