Question

an electrolyte is added to hydrated ferric oxide sol in water

Answer 1

When a beam of light is passed through a colloidal solution, then light scatter from the particles. This is known as the Tyndall effect. This scattering of light illuminates the path of the beam in the colloidal solution.

Upon dissolved in ferric oxide solution, NaCl dissociates into Na+ and Cl-­ ions. Particles of ferric oxide solution are positively charged. Thus, they get coagulated in the presence of negatively charged Cl-ions.

 

 The colloidal particles are charged either a positive or negative charge. The dispersion medium carries an equal and opposite charge which eventually makes the system neutral. Under the influence of an electric current, the colloidal particles move towards the oppositely charged electrode. When they come in contact with the electrode, they lose their charge and stay back.