Tyndall Effect
Tyndall observed this phenomenon in
1869. He observed that when a beam of
light is allowed to pass through a colloidal solution, the path of light gets
illuminated. This phenomenon is known as Tyndall Effect. It occurs because light is
scattered by particles present in colloidal solution. The intensity of the scattered
light depends on the difference between the refractive indices of the dispersed
phase and the dispersion medium. Greater is the difference, greater the intensity of
light.
light is allowed to pass through a colloidal solution, the path of light gets
illuminated. This phenomenon is known as Tyndall Effect. It occurs because light is
scattered by particles present in colloidal solution. The intensity of the scattered
light depends on the difference between the refractive indices of the dispersed
phase and the dispersion medium. Greater is the difference, greater the intensity of
light.
Brownian Movement
There are continuous collisions between the colloidal particles and molecules ofdispersion medium which are in constant motion and passes kinetic energy to colloidal
particles by striking it from all sides. This results into zigzag movement of colloidal
particles. This zigzag movement of colloidal particles is known as Brownian movement.
Colligative Property
Colligative properties depend upon the
number of moles of solute present in
given mass of solvent. It does not depend on nature of solute particles. Colloidal
particles are not simple molecules, they are aggregations of molecules. Hence,
all colloidal dispersions give low value of osmotic pressure, depression in freezing
point and elevation in boiling point.
given mass of solvent. It does not depend on nature of solute particles. Colloidal
particles are not simple molecules, they are aggregations of molecules. Hence,
all colloidal dispersions give low value of osmotic pressure, depression in freezing
point and elevation in boiling point.
Electrophoresis
The movement of colloidal particles
under the influence of electric field is
called Electrophoresis. When an electric field is applied across the colloidal
solution, the colloidal particles migrate to oppositely charged electrode where
they get neutralized. This phenomenon is known as electrophoresis.
called Electrophoresis. When an electric field is applied across the colloidal
solution, the colloidal particles migrate to oppositely charged electrode where
they get neutralized. This phenomenon is known as electrophoresis.
Electro Osmosis
When electrophoresis of dispersed
particle in a colloidal system is prevented by
some suitable means, it is observed that dispersion medium itself begins to move
in an electric field. This phenomenon is known as electro osmosis.
some suitable means, it is observed that dispersion medium itself begins to move
in an electric field. This phenomenon is known as electro osmosis.