This video lecture from Group VA and Group VIA Elements (F.Sc. second year Chemistry) covers the preparation and chemical reactions of nitrous acid. This oxyacid can be prepared by dissolving dinitrogen trioxide or nitrous anhydride in water or by simply dissolving nitrogen oxide gas in the absence of air as seen in the previous lectures. Pure nitrous acid solution can be prepared by the reaction between ice cold barium nitrate and sulfuric acid. The decomposition reaction and redox reaction mechanism is also covered for nitrous acid. Find more e-learning material and educational video lectures in Urdu at maktab.pk. These videos are free to use for promotional and commercial purpose by keeping the credits to Maktab.