Medium MCQ +4 / -1 PYQ · JEE Mains 2023

Which of the following salt solutions would coagulate the colloid solution formed when $\mathrm{FeCl_3}$ is added to $\mathrm{NaOH}$ solution, at the fastest rate?

  1. A 10 mL of 0.15 mol dm$^{-3}$ CaCl$_2$
  2. B 10 mL of 0.2 mol dm$^{-3}$ AlCl$_3$ Correct answer
  3. C 10 mL of 0.1 mol dm$^{-3}$ Na$_2$SO$_4$
  4. D 10 mL of 0.1 mol dm$^{-3}$ Ca$_3$(PO$_4$)$_2$

Solution

In the coagulation of a negative sol, the flocculating power is in the order. <br/><br/> $\therefore \mathrm{Al}^{3+}>\mathrm{Ba}^{2+}>\mathrm{Na}^{+}$and $\mathrm{FeCl}_{3}$ with $\mathrm{NaOH}$ forms a negative sol. <br/><br/> $\therefore \mathrm{AlCl}_{3}$ coagulate it most.

About this question

Subject: Chemistry · Chapter: Surface Chemistry · Topic: Adsorption

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