Question

Mixing of the positively charged colloidal solution with negatively charged colloidal solution brings ______. The decreasing order of coagulating power of $N{a}^{+}$, $B{a}^{2+}$ and $A{l}^{3+}$ for negatively charged colloidal solution is ______.

• A. mutual coagulation, $N{a}^{+}$ > $B{a}^{2+}$ > $A{l}^{3+}$
• B. mutual coagulation, $A{l}^{3+}$ > $B{a}^{2+}$ > $N{a}^{+}$
• C. coagulation, $N{a}^{+}$ > $B{a}^{2+}$ > $A{l}^{3+}$
• D. peptization, $A{l}^{3+}$ > $B{a}^{2+}$ > $N{a}^{+}$

Answer 1

The correct option is B mutual coagulation, $A{l}^{3+}$ > $B{a}^{2+}$ > $N{a}^{+}$

• The process of settling of colloidal particles is called coagulation or precipitation of the sol.

• When an excess of an electrolyte is added, the colloidal particles are precipitated. The reason is that colloids interact with ions carrying a charge opposite to that present on themselves. This causes neutralization leading to their coagulation. The ion responsible for the neutralization of charge on the particles is called the coagulating ion. A negative ion causes the precipitation of positively charged sol and vice versa.
  

• 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
  

• Hence,correct order of coagulating power is $N{a}^{+}<B{a}^{2+}<A{l}^{3+}$