Question

A colloidal solution is subjected to an electric field than colloidal particles more towards anode. The amount of electrolytes of BaCl₂, AlCl₃ and NaCl required to coagulate the given colloid is in the order

• A. NaCl > BaCl₂ > AlCl₃
• B. BaCl₂ < AlCl₃ > NaCl
• C. AlCl₃ = NaCl = BaCl₂
• D. AlCl₃ > BaCl₂ > NaCl

Answer 1

The Correct Option is A

Coagulation of a colloidal solution depends on the electrolyte’s ability to neutralize the charge on colloidal particles. The more the valency of the cation, the more efficient the electrolyte is in coagulating the colloid.

The order of coagulation power is:

• NaCl has a single positive ion (Na⁺) and is least efficient in coagulation.
• BaCl₂ has a divalent cation (Ba²⁺) and is more efficient than NaCl.
• AlCl₃ has a trivalent cation (Al³⁺) and is the most efficient at coagulating the colloidal particles.

Thus, the order of coagulation is NaCl > BaCl₂ > AlCl₃.

So, the correct answer is (A): NaCl > BaCl₂ > AlCl₃.