3. Colloids

Colloid Solution

Colloid State : A substance is said to be  in colloidal state when the size of the particle of disperse phase is greater than particle of true solution and less than that of  suspension solution particle, their range of diameters between 1 and 1000 nm (10^–9 to 10^–6 m).

Colloid solution : It is a heterogeneous system consisting of 2 phase :

(1) Disperse Phase (D.P) : The phase which is dispersed through the medium is called dispersed phase or discontinuous phase or internal phase.

(2) Dispersion Medium (D.M) : A medium in which colloidal particles are dispersed is called dispersion medium. It is also known as continuous phase or outer phase or external phase.

Colloidal solution = D.P. + D.M.

Ex. In Gold sol, Gold is D.P and water is D.M.

Diffrenciating point of colloids :

(1) A colloid is a heterogeneous system in which one substance is dispersed (dispersed phase) as very fine particles in another substance called dispersion medium.

(2) The solution and colloid essentially differ from one another by particle size.

* In a solution, the particles are ions or small molecules.

* In a colloid, the dispersed phase may consist of particles of a single macromolecule (such as protein or synthetic polymer) or an aggregate of many atoms, ions or molecules.

(3) Colloidal particles are larger than simple molecules but small enough to remain suspended. They have a range of diameters between 1 and 1000 nm (10^–9 to 10^–6 m).