Question

Which of the following acts as the best coagulating agent for ferric hydroxide sol?

• A. Potassium ferrocyanide
• B. Potassium chloride
• C. Potassium oxalate
• D. Aluminium chloride

Answer 1

The correct option is A Potassium ferrocyanide

• The process of settling of colloidal particles is called coagulation or precipitation of the sol.
• The greater the valence of the flocculating ion added, the greater is its power to cause precipitation. This is known as a Hardy-Schulze rule.
  
• Given, ferric hydroxide sol is a positive sol, and hence to coagulate it by using a negative sol.
• Among all the options Pottasium ferrocyanide($K_{4}Fe\left(CN{)}_6.3H_{2}O\right)$ the ion $\left(Fe\right(CN{)}_6{)}^{4-}$ is having the maximum valence and hence acts as best coagulating agent for Ferric Hydroxide sol.