Chemistry

Properties of colloidal solutions
Heterogeneous Nature : A colloidal solution is heterogeneous in nature. It consists of two phases : dispersed phase and dispersion medium.
Filtrability : The size of the colloidal particles is less than the pores of a filter paper, and, therefore, they easily pass through a filter paper. Colloidal particles however, cannot pass through the parchment paper or an animal membrane or ultra-filter.
Tyndall Effect : When a strong beam of light is passed through a colloidal solution placed in dark place, the path of the beam gets illuminated by a bluish light . This phenomenon is called Tyndall effect. The phenomenon is due to the scattering of light by the colloidal particles.
The same phenomenon is noticed when a beam of sunlight enters a dark room through a small slit, due to scattering of light by dust particles in the air.
Visibility : Colloidal particles are too small to be seen by the naked eye. They however, scatter light and become visible when viewed through an ultra microscope.
Brownian movement : When colloidal particles are seen under an ultra microscope, the particles are found to be in constant motion in zig-zag path in all possible directions. This zig-zag motion of colloidal particles is called Brownian movement. The movement of the particles is due to the collisions with the molecules of the dispersion medium.
Diffusion : Colloidal particles diffuse from a region of higher concentration to that of lower concentration. However, because of their bigger sizes colloidal particles move slowly and hence diffuse at slower rate.
Sedimentation or settling : Under the influence of gravity, the solute particles tend to settle down very slowly. This rate of settling down or sedimentation can be accelerated by the use of high speed centrifuge called ultra-centrifuge.