Q. Why is high temperature not used in preparing Nitric acid in the laboratory?
Nitric acid is prepared in the laboratory by heating a mixture of sodium nitrate and dark H2SO4 to 200°C. Nitric acid is also produced at high temperatures i.e. 800°C. But the reaction does not take place at high temperatures.
Why is high temperature not used in preparing Nitric acid in the laboratory?
(i) Nitric acid decomposes at high temperatures to produce nitrogen dioxide, water and oxygen.
4HNO3 = 4NO2 + O2 + 2H2O
(ii) At high temperatures the apparatus is likely to burst.
(iii) The solid sodium sulphate (Na2SO4) produced at high temperatures accumulates on the vessel in such a way that it cannot be easily removed from the vessel. But sodium bi-sulphate (NaHSO4) formed at low temperatures is liquid and can be easily removed from the container.