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
Correct Answer: D
Explanation
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
