This video lecture from Group VA and Group VIA Elements (F.Sc. second year Chemistry) covers the preparation of Ortho-phosphoric acid. Ortho phosphoric acid can be prepared by dissolving phosphorus pentaoxide in water or by the action of concentrated nitric acid on phosphorus. It can also be prepared by the reaction of water with phosphorus penta-chloride or by heating a mixture of bone ash and sand. 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.