Question

The electrical charge on a colloidal particle is indicated by :

• A. Brownian movement
• B. electrophoresis
• C. ultra microscope
• D. molecular sieves

Answer 1

Answer: (B)

electrophoresis

The colloidal particles carry an electric charge. The colloidal solution is taken in a U- tube and two platinum electrodes are dipped in the sol as shown in the figure. The current is then switched on. On closing the circuit, it is found that colloid particles move to the oppositely charged electrode and on reaching that electrode, they get discharged. As soon as the charge of the particles is neutralized, they aggregate and settle down. This movement of colloid particles in electric field is known as electrophoresis in case of the true solutions.