Question

write the property of colloids

Answer 1

Following are the important physical properties of colloidal solutions: 

Heterogeneity: Colloidal solutions are heterogeneous in nature. These consist of two phases-dispersed phase and dispersion medium. 

Visibility of dispersed particles: Although colloidal solutions are heterogeneous in nature, yet the dispersed particles present in them are not visible to the naked eye and they appear homogenous. This is because colloidal particles are too small to be visible to the naked eye. 

Filterability: Due to very small size, the colloidal particles pass through an ordinary filter paper. However, they can be retained by animal membranes, cellophane membrane and ultrafilters. 

Stability: Lyophilic sols in general and lyophobic sols in the absence of substantial concentrations of electrolytes are quite stable and the dispersed particles present in them do not settle down even on keeping. However, on standing for a long time, a few colloidal particles of comparatively larger size may get sedimented slowly. 

Colour: The colour of a colloidal solution depends upon the size of colloidal particles present in it. Larger particles absorb the light of longer wavelength and therefore transmit light of shorter wavelength. For example, a silver so having particles of size 150nm appears violet, whereas that having particles of size 60nm appears orange yellow.

Answer 2

Answer:

A colloid ( or colloidal solution) appears to be homogenous but actually it is heterogeneous.

• The size of particles in colloidal solution is intermediate to that of solution particles and suspension particles (i.e the particle size is in between 1nm - 100nm.)

• The particles of colloidal solution are unstable.

• The particles of colloid can pass through a filter paper. They can only get separated by the process of centrifugation.