Introduction for Definition of colloids substance:
Colloid substance is a heterogeneous combination in which particles having size between 10-7to 10-4 cm are dispersed in a continuous dispersion medium. The continuous medium in a colloid is called the dispersion medium and the particles form the dispersed phase. The particles of the dispersed phase are generally called colloidal particle.
Classification of Colloids - Definition of Colloids Substance:
The range of the colloidal particles is not visible to naked eye. Colloidal substance is also referred to as sols. If the dispersion medium is water they are called hydrosols and if it is alcohol, they are called alcosols. Colloids play an important part in our day life.
Example:
- Vegetables
- Milk
- Blood
- Toothpaste
- Fruit juices
- Bread
- Office paste (gum)
- Jelly
Classification of colloids:
Depending on the physical status of the dispersed phase and dispersion medium the colloids can be classified into following types.
dispersed phase | dispersion medium | common name | example |
gas | liquid | foam | forth, whipped cream, soap leather, fire extinguisher foam |
gas | solid | foam | pumice, stone, foam, rubber |
liquid | gas | aerosol | fog, liquid sprays, mist |
liquid | liquid | emulsion | milk, hair cream, oil in water emulsion |
liquid | solid | gel | cheese, butter, jam, jelly |
solid | gas | solid aerosol | smoke, dust |
solid | liquid | sol | paints, gold sol, cell fluids, toothpaste, milk of magnesia, mud |
solid | solid | solid sol | coloured glasses, gems, precious stones, pigmented plastics |
Colloids definition can also be classified on the origin of attraction or affinity of dispersed phase and dispersion medium for each other. On this basis colloids have been classified as
- Lyophilic colloids
- Lyophobic colloids
Definition of Lyophilic colloids:
These are solvent (dispersion medium) loving colloids. They directly pass into colloidal state when brought in contact with the solvent. Gelatin and starch are water loving (or hydrophilic) colloids.
Definition of Lyophobic colloids:
These are solvent hating colloids. They do not easily pass into colloidal state when brought in contact with the solvent,
Example:
Metals
Characteristics Properties of Colloids Substance - Definition of Colloids Substance:
- Heterogeneous nature
- Particle size
- Stability
- Filtration
- Brownian movement
- Tyndall effect
- Electrophoresis
- Coagulation
