This video lecture from Group VA and Group VIA Elements (F.Sc. second year Chemistry) covers the chemical reactions of Ortho-phosphoric acid. The reactions include those in which it reacts as a weak tri-basic acid and reacts with bases to form salt and water in a neutralization reaction. Other reactions include the decomposition of orthophosphoric acid into pyrophosphoric acid and later into metaphosphoric acid at elevated temperatures. 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.