Tuesday, August 20, 2013

General Properties of Colloidal Solutions

         a).     Filterability
                        Colloidal particles can pass through ordinary filter paper (diameter of pores in ordinary filter paper is about 10-6m).
         b).     Molecular weight
                        Colloidal particles are formed by aggregation of a large number of small molecules, e.g starch (C6H10O5)n. Hence they possess very high molecular weights.
         c).     Osmotic Pressure
                        As colloidal particles is an aggregation of large number of particles, the number of particles in sol is very small. Therefore, osmotic pressure of sol is very low. The measurement of osmotic pressure has been used for determination of molecular weights of colloids.
         d).     Colour
                        The colour of sol depends on the wavelength of light. Scattered by colloidal particles which in turn depends on the size of the particles on which the wavelength of scattered light depends. Gold sol can be red, blue or purple depending upon size of particle.

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