Question

Sedimentation potential is reverse of:
a) Electro-osmosis
b) Electrophoresis
c) Electro kinetic potential
d) Steaming potential

Answer 1

Knowledge of sedimentation potential and electrophoresis is important to answer these kinds of questions. Sedimentation potential is the movement of dispersed phase particles forcefully under the action of centrifugation or gravity in a particular medium.

Complete answer:
Electro osmosis is the method of movement of dispersed medium under the influence of electric field when the movement of dispersed particles is restricted by some suitable means.Electro osmosis is the special case of electrophoresis where by the action of some suitable solvent the movement of dispersed particles is stopped and then the movement of dispersed medium gets started under the influence of electric field.
Electro kinetic potential is also known as zeta potential is the potential difference between the fixed layer and the diffused layer of oppositely charged colloidal solutions.
Electrophoresis is the method to determine the charge on colloidal particles. When in a colloidal solution, electric potential is applied by dipping platinum electrodes, the colloidal particles of positive charge move towards the negative electrode and particles of negative charge move towards the positive electrode. This movement under the action of the electric field is known as electrophoresis.
After this the electrodes are taken out and discharged which causes the dispersed particles to precipitate.
But in the case of sedimentation potential, particles which are in rest are disturbed and by the action of centrifugation or gravity which cause movement in the medium. This process is the reverse of electrophoresis, where the colloidal particles are charged, and are not in rest. Thus movement is possible easily.

Hence the correct option is (b).

Note:
These methods are also used for the coagulation of lyophobic sols as after the separation of charges the electrode plates, they lose their charges, come nearer to each other. After that they aggregate, precipitation occurs easily.