Explain what is observed when
(i) an electric current is passed through a sol
(ii) a beam of light is passed through a sol
(iii) an electrolyte (say NaCl) is added to ferric hydroxide sol
(i) When NaCl is added to hydrated ferric oxide solution, then coagulation
will take place. A negatively charged solution is obtained with absorption
(ii) When electric current is passed through a colloidal solution, the positively
charged particles move towards cathode while negatively charged particles
move towards anode where they lose their charge and get coagulated.
The phenomenon is known as Electrophoresis.
(iii) When a beam of strong light is passed through a colloidal solution,
scattering of light occurs by colloidal particles and the path of light
becomes visible and the phenomenon is known as Tyndall effect.