Question

Arsenic (III) sulphate forms a sol with a negative charge. Which of the following ionic substances should be most effective in coagulating the sol?
A) $KCl$
B) $MgC{l_2}$
C) $A{l_2}{\left( {S{O_4}} \right)_3}$
D) $N{a_3}P{O_4}$

Answer 1

We comprehend that the Coagulating power relies upon such a colloid. In the event that the blend is negative, the molecule with most noteworthy electric charge can have the absolute best coagulating power and in the event that the colloid is positive, at that point the particle with most elevated electric charge will have the most noteworthy coagulating power.

Complete step by step answer:
Let us examine coagulation.
Coagulation is seen in surface science. It is the cycle in colloidal particles total with one another and structures bigger particles and these particles settle down as hastens. Coagulation measure is additionally alluded to as precipitation and flocculation and this cycle is completed by the electrolytes which are added to the arrangement.
Hardy-Schulze rule:
In the event that the valency of oppositely charged particles of the electrolyte being added is more prominent, quicker is the coagulation. In the event that the valency of a coagulating particle is more prominent than more noteworthy is the coagulation power.
Flocculation esteem is contrarily corresponding to the coagulating intensity of the particle.
To coagulate negative sol of Arsenic (III) sulphate, the coagulation intensity of various cations decline in the order $A{l^{3 + }} > M{g^{2 + }} > {K^ + } > N{a^ + }$. Subsequently, the flocculation esteem increments in the order $A{l^{3 + }} < M{g^{2 + }} < {K^ + } < N{a^ + }$. The flocculating values (in milli moles/liter) of $A{l^{3 + }} > M{g^{2 + }} > {K^ + } > N{a^ + }$ are $0.093$, $0.72$, $50$ and $51$ separately. Hence, $A{l_2}{\left( {S{O_4}} \right)_3}$ is the best in coagulating the sol.

So, the correct answer is Option C.

Note: We have to remember that there are 2 assortments of colloids, they're positive and negative colloids. Positive colloids or SOLs: Positive sols have electric charge and each one the metal hydroxide are positive sols. Negative colloids or SOLs. Negative sols have electric charge and all the metal sulfides are negative sols.