In the laboratory preparation of trioxonitrate (V) acid the nitrogen(iv) oxide formed as a by-product is removed by

  • A further heating
  • B adding concentrated H2SO4
  • C cooling the acid solution with cold water
  • D bubbling air through the acid solution
jamb 2017chemistry

The correct answer is D. bubbling air through the acid solution

Bubbling of air through the acid solution removes deposited oxides of nitrogen.

Nitric acid is prepared in the laboratory by heating a nitrate salt with the concentrated acid.

NaNO3 + H2SO4 → NaHSO4 + HNO3

Vapours of nitric acid are condensed to a brown liquid in a receiver cooled under cold water. "Dissolved oxides of nitrogen" e.g NO2 are removed by redistillation or blowing a current of carbondioxide or dry air through the warm acid

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