Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
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sulphuric acid : H2SO4
sodium chlorite : NaClO2
sodium chlorate : NaClO3
sodium nitrite : NaNO2
Class:
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elem=N,Cl
redox
Summary:
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Chlorite ion and nitrite ion react with each other in acidic medium, giving off
quite some heat, while this does not occur with chlorate and nitrite.
Description:
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Dissolve some sodium chlorate and excess amount of sodium nitrite in a few ml
of water and mix the two liquids: When this is done no visible reaction occurs.
Add a few drops of 20% sulphuric acid: The liquid becomes pale blue and
bubbles of a gas are produced. The air above the liquid becomes very pale
brown. The pale blue color of the liquid hardly is visible. It looks like the
chlorate does not react with the nitrite or only very slowly. The liquid does
not heat up at all.
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Dissolve some sodium chlorite and excess amount of sodium nitrite in a few ml
of water and mix the two liquids: When this is done no visible reaction occurs.
Add a few drops of 20% sulphuric acid: The liquid becomes very pale blue,
hardly visible, and a small amount of colorless gas bubbles are produced. The
liquid becomes rather hot. The air above the liquid becomes pale brown.
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This pair of simple experiments shows that chlorite and nitrite quickly react
when they are in acidic medium and that a lot of heat is produced in that
reaction. Most likely the chlorite is reduced to chloride and the nitrite is
oxidized to nitrate.