Colloids
Properties of Colloids
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.
Brownian Movement
There are continuous collisions between the colloidal particles and molecules of dispersion 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.
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.
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.
8types of colloidal dispersion
* solid particles dispersed in a gas (solid aerosol); example: dust in air
* liquid droplets dispersed in
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.
Brownian Movement
There are continuous collisions between the colloidal particles and molecules of dispersion 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.
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.
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.
8types of colloidal dispersion
* solid particles dispersed in a gas (solid aerosol); example: dust in air
* liquid droplets dispersed in