This video lecture from Reaction Kinetics (F.Sc. first year Chemistry) covers the specific rate constant which is also called velocity constant of a reaction. It is the constant which helps to equate the active masses of reactants with the rate of reaction. It is defined as the rate of reaction as the concentrations of reactants are taken as one (i.e. uni-molar). Rate constant varies for each reaction and is also a function of several parameters including nature of reactants and temperature. The law of mass action which helps to determine the rate law is also discussed. 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.