Question

Gold sol is to be prepared from rods of gold.

1. Which method do you suggest? 

2. Explain. 

3. Distinguish between sol and gel with suitable examples for each.

Answer 1

1. Electrical disintegration method – Bredig’s Arc Method.

2. An electric arc is struck between electrodes of the metal immersed in dispersion medium. The heat produced vapourises the metal which then condenses to form colloids.

3. Difference between sol and gel with suitable examples :

• Sol – Colloids in which dispersed phase is solid and dispersion medium is liquid, e.g. Paints, Cell fluids.
• Gel – Colloids in which dispersed phase is liquid and dispersion medium is solid, e.g. Cheese, Butter.