Question

Define the following terms with an example in each case :
(i) Macromolecular sol
(ii) Peptization
(iii) Emulsion

Answer 1

Macromolecular sol : These are the colloids obtained by dissolving macromolecules (big size molecules) having large molecular masses in a suitable liquid. In these, the dispersed phase particles have size in the colloidal range (1 nm - 100 nm). e.g., starch, cellulose etc.
(ii) Peptization : It is a process of converting a fresh precipitate into colloidal particles by shaking it with the dispersion medium in the persence of a small amount of a suitable electrolyte. e.g., A freshly precipitated $Fe(OH{)}_3$ is converted into colloidal solution by adding small quantity of $FeC{l}_3$ to the solution of $Fe(OH{)}_3$.
(iii) Emulsion : An emulsion is a colloidal dispersion in which both the dispersed phase and the dispersion medium are liquids which are otherwise immiscible. e.g., milk, cod liver oil etc.