1. Colour:
The colour of a sol is not always the same as the colour of the substance in the bulk. For example, bluish tinge is given by diluted milk in reflected light and reddish tinge in transmitted light.
2. Size:
The size of colloidal particles ranges from Imp to 1pm diameter.
3. Colloidal solutions are heterogeneous in nature:
They have two distinct phases. Experiments like dialysis. ultrafiltration show the heterogeneous in nature but they are considered as borderline cases.
4. Filterability:
As the size of pores in ordinary filter paper are large, the colloidal particles easily pass through the ordinary filter papers.
5. Non setting nature:
Colloidal solutions are quite stable i.e., they are not affected by gravtiy.
6. Concentration and density:
When the colloidal solution is dilute, it is stable. When the volume of medium is decreased, coagulation occurs. Density of sol decreases with decrease in the concentration.
7. Diffusability:
Unlike true solution, colloids diffuse less readily through membranes.
8. Colligative properties:
The colloidal solutions show colligative properties such as elevation of boiling point, depression in freezing point and osmotic pressure. These. properties are used to determine molecular weight of colloidal particles.
9. Shape of colloidal particles:
Colloidal particles have various shapes
Collidal particle
1. AS2S3
2. Fe(OH)3 (blue gold sol)
3. W3O5 sol(tungstic acid sol)
Shape
1. Spherical
2. Disc (or) plate like
3. Rod like
10. Optical property:
The path of the light is visible when it is passes through a colloidal solution due to the scattering of light by colloidal particles. This is known as Tyndall effect.
11. Kinetic property:
When colloidal solution is viewed through an ultra microscope, they showed a random, zigzag ceaseless motion which is called Brownian movement.
12. Electrical property:
Helmholtz double layer. electrophoresis and electro osmosis are electrical properties of colloids.
