Question -
Answer -
(i)┬аWhen a beam of light is passed through a colloidal sol.
(ii)┬аAn electrolyte, NaCl is added to hydrated ferric oxide sol.
(iii)┬аElectric current is passed through a colloidal sol?
Answer
(i)┬аWhen abeam of light is passed through a colloidal solution, then scattering of lightis observed. This is known as the Tyndall effect. This scattering of lightilluminates the path of the beam in the colloidal solution.
(ii)┬аWhen NaClis added to ferric oxide sol, it dissociates to give Na+┬аand Cl-┬нions. Particles of ferric oxide sol are positively charged. Thus, they getcoagulated in the presence of negatively charged Cl-┬аions.
(iii)┬аThecolloidal particles are charged and carry either a positive or negative charge.The dispersion medium carries an equal and opposite charge. This makes thewhole system neutral. Under the influence of an electric current, the colloidalparticles move towards the oppositely charged electrode. When they come incontact with the electrode, they lose their charge and coagulate.