Question

Why is gelatin mixed with gold sol?

• A. Gold sol is lyophobic sol, gelatin acts as stabilising agent.
• B. Gold sol is lyophilic sol, gelatin acts as stabilising agent.
• C. Gelatin produces negative charge on gold particles in gold sol.
• D. Gelatin helps gold sol to get its critical micelle concentration.

Answer 1

The correct option is A Gold sol is lyophobic sol, gelatin acts as stabilising agent.

• Lyophilic sols are more stable than lyophobic sols. This is due to the fact that lyophilic colloids are extensively solvated, i.e., colloidal particles are covered by a sheath of the liquid in which they are dispersed.
• Lyophilic colloids have a unique property of protecting lyophobic colloids.
• When a lyophilic sol is added to the lyophobic sol, the lyophilic particles form a layer around lyophobic particles and thus protect the latter from electrolytes. Lyophilic colloids used for this purpose are called protective colloids.
• Gelatin is a Lyophilic sol and when it is added to gold sol which is lyophobic sol it acts as a stabilizing agent by protecting the colloid.
• Hence, options A is the right answer.