Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
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sodium nitrite : NaNO2
trichloroisocyanuric acid : C3N3O3Cl3
Class:
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elem=N,Cl
redox
Summary:
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When trichloroisocyanuric acid and sodium nitrite are mixed then no reaction
occurs. As soon as some water is added a fairly vigorous reaction starts. A
brown gas mix is produced, and the material starts foaming. The gas inside the
foam bubbles is colorless and only when bubbles pop, a brown gas is observed.
Description:
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Add some solid dry sodium nitrite to a piece of trichloroisocyanuric acid
(TCCA): No reaction occurs.
Add a tiny amount of water, such that the solids are just wetted: Bubbles of
gas are produced, the gas mix above the solids becomes brown.
Add a little more water (a few drops): A vigorous reaction occurs and the
material starts foaming a lot. Half of the test tube is filled with big bubbles
of foam and the gas inside the bubbles is colorless.
With a glass rod, touch the big bubbles of foam, such that the bubbles pop: The
colorless gas is mixed with air and the mix becomes brown.
Explanation: In the presence of a little water, sodium nitrite dissolves and
this dissolved sodium nitrite reacts with TCCA and water in which one of the
reaction products is HCl. This makes the solution strongly acidic and this
leads to formation of NO and NO2.