nintey2
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Registered: 7-6-2016
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Potassium/sodium nitrite and concentrated acid: evolution of gas unavoidable?
So I believe the formula for this reaction is and it is 1 gram potassium nitrite to every 10 mL concentrated H2SO4
2 KNO2 + H2SO4 = K2SO4 + NO2 + NO + H2O
and the products are potassium sulfate, nitrogen dioxide, nitric oxide and water.
I am looking to create the Liebermann reagent but I am hoping to avoid the evolution of any poisonous gases. Is it possible to make a liter of the
reagent without requiring a fume hood?
Can you add dry ice to the reaction to cool it and avoid an evolution of gas?
I know stirring the h2so4 and adding the KNO2 slowly is the proper technique for the creation of the reagent, but is there any other thing I can do to
ensure that the gas does not evolve?
Thank you for your help and I apologize if this question is extremely rudementry
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woelen
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Registered: 20-8-2005
Location: Netherlands
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A liter of this reagent? That's a lot! This is a reagent which you should make just before use. You cannot store it for a long time.
If you add a nitrite salt to conc. H2SO4, then the decomposition is not as bad as when nitrite is added to dilute aqueous acid. You can dissolve NaNO2
in H2SO4 with just very little production of gas. What you obtain is (NO)HSO4 plus water and sodium bisulfate. This (NO)HSO4 is fairly stable and can
be kept around for an hour or so, allowing you to prepare it just before the reaction you intend with it and then slowly adding it. It is not so
stable that you can make a bottle full of this and store it for a long time.
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