Description of experiment
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Needed compounds:
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hydrochloric acid : HCl
acetic acid : CH3COOH
sodium chlorite : NaClO2
Class:
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elem=Cl
redox
Summary:
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When sodium chlorite solution is acidified with acetic acid, then a brown
solution is obtained, which on addition of more acetic acid becomes lighter and
which on addition of hydrochloric acid becomes bright yellow.
Description:
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Prepare 1 ml of 30% solution of sodium chlorite and add a single drop of
glacial acetic acid: When the acid reaches the liquid, at first not much seems
to happen. on mixing of the two liquids, the resulting liquid becomes very pale
yellow.
On standing, however, the liquid slowly darkens and after a few minutes, the
liquid has a fairly strong brown color. The gas-mix above the liquid is VERY
pale yellow, almost colorless, but when observed caefully, the gas mix is not
totally colorless.
Add a few more drops of acetic acid: The liquid becomes lighter again. The
liquid remains brown, but the intensity of the color is reduced.
Add a few drops of hydrochloric acid: At once the liquid becomes intense
yellow, but no bubbles of ClO2 are formed. After a while of standing, however,
the gas mix above the liquid also is yellow.