In the present lecture, the experiments on viscosity, surface tension and distribution coefficient were described. The viscosity of two liquids was compared by making use of an Ostwald Viscometer. The use of viscosity measurement to determine the average molecular weight of a polymer was also outlined.

If in a system of two immiscible or slightly miscible solvents, a substance, soluble in both the solvents is added, then the added substance distributes itself between the two liquids in a definite manner depending upon its solubility. At equilibrium, the ratio of the concentrations of the solute in the two liquids is constant at a given temperature and is called the distribution coefficient or partition coefficient. The determination of the partition coefficient of iodine between chloroform and water was described. The partition law was also used to determine the equilibrium constant between KI, I₂ and KI₃.