Properties Of Colloids

Properties Of Colloids

What is a colloid solution?

A colloidal solution is a type of a mixture which consists of particles whose size varies between 1 to 1000 nanometers. In colloidal solution the particles are distributed evenly. During this process the particles do not settle down. This is one of the best know thing about colloidal solutions.

Properties of colloids and their variation are a well-known area ever since the primitive age. The best example to prove their familiarity with us is that we know from very early times that coagulation of milk results in the formation of curd.

Physical properties of colloids

  1. The nature of the colloidal solution is heterogeneous i.e. unlike. These solutions dwell with two different phases:
    • Dispersed medium
    • Dispersed phase
  2. Despite the fact that colloidal dispersions are unlike in description (nature), yet the dispersed fragments are not detectable by the human eye. This is due to the microscopic size of the particles in the solution.
  3. The color of the colloidal dispersion is determined by particles in the solution based on their size. The wavelengths of light that is absorbed will be longer if the size of the particle is large.
  4. As a result of its size, the colloidal fragments can easily be passed through a traditional filter paper. However, these particles can be filtered by using membranes such as animal, cellophane, and ultrafilters.

Electrical properties of colloids

  1. Electrical double layer theory: In this theory, charge is imparted to the particles by placing ions which are adsorbed preferentially at immovable points which for the first layer. The second layer consists of diffused mobile ions. The charge present on both the layers is equal. This two-layer arrangement leads to a development of potential called zeta or Electrokinetic potential. As a result of this potential developed across the particles, under the influence of electric field these particles move.

  2. Electrophoresis: It is a process in which an electric field is been applied to a colloidal solution which is responsible for the movement of colloidal particles. Depending upon the accumulation near the electrodes the charge of the particles can be predicted. The charge of the particles is positive if the particles get collected near a negative electrode and vice versa.

    Electrophoresis - Properties Of Colloids

  3. Electro-osmosis: It is a process in which the dispersing medium of the colloidal solution is brought under the influence of electric field and the particles are arrested.

    Electro osmosis - Properties Of Colloids

Optical properties of colloids

Tyndall effect is defined as the phenomenon in which light is scattered by the colloidal particles. The light is been absorbed by the particles present in the solution. Once the light is been absorbed a part of the light gets scattered in all the directions. The result of scattering exhibits this effect.

Kinetic properties of colloids

During the observation of the colloidal dispersion under an ultra-microscope, it is clearly seen that the particles are in a continuous movement in the solution. This random zig-zag movement of the particles in the colloidal solution is called Brownian effect. This movement is mainly due to the unique bombardment of the molecules present in the dispersed medium on the colloidal particles.

To get more details on this topic you can download BYJU’S – India’s largest k-12 app.


Practise This Question

When an excess of a very dilute aqueous solution of KI is added to a very dilute aqueous solution of silver nitrate, the colloidal particles of silver iodide are associated with which of the following Helmholtz double layer?