Colloids

An ordinary solution consists of a solvent and a solute. The particles of a solute in an ordinary solution are usually either normal molecules or ions. In some solution the particles of solute are much larger: they may consist of aggregates of hundreds of ordinary sized molecules or even of a single larger or macro-molecule. Such as proteins dissolved in water. Such kind of solution is referred to as colloidal solution.

A colloidal solution cannot always be distinguished from a true solution with the naked eye. The particles, even though they may consist of some thousands of molecules, will pass through a filter paper, and cannot be seen under the microscope. A colloidal solution, however, is a two-phase system, whereas a true solution is regarded as being homogeneous, and therefore consists of only one phase. Colloidal are intermediate between solutions and precipitates, and there is a gradual transition between the two.

In gist, a colloidal solution is a heterogeneous two−phase system in which a substance is distributed in colloid state (i.e., of diameter between 2 x 10^-4 to 1 x 10^-7 cm) in an insoluble medium. The particle of the dispersed substance are in discontinuous phase called dispersed phase; while insoluble medium or external phase in which they are distributed is called dispersion medium. Besides these, a colloidal solution some times have a stabilizing agent which keeps the colloidal particles apart, thereby avoiding their coalescence and consequent settling under the influence of gravity.

Types of Colloids

Other Resourceful Topics

• Hydrophillic and Hydrophobic Colloids
• Characterstics of Colloidal Solution
• Stability of Colloids