Question

The coagulation value in millimoles per litre of electrolytes used for the coagulation of $A{g_2}{S_3}$ are as below:
$NaCl$=$52$
$KCl$=$51$
$BaC{l_2}$=$0.69$
$MgS{O_4}$=$0.22$
The correct order of their flocculating power is:
A. $MgS{O_4} > BaC{l_2} > KCl > NaCl$
B. $MgS{O_4} > KCl > BaC{l_2} > NaCl$
C. $MgS{O_4} > NaCl > BaC{l_2} > KCl$
D. $MgS{O_4} > BaC{l_2} > NaCl > KCl$

Answer 1

Hint: We can say the precipitation of colloidal solution, with the support of addition of excess of an electrolyte is called flocculation or coagulation.

Complete step by step answer:
The precipitation of colloidal solution, with the support of addition of extra electrolyte is known as flocculation or coagulation.
The electrolyte is called a flocculating agent.
The power of an electrolyte to precipitate a colloidal solution is called flocculating power.
It is determined with the help of Hardy Schulze Rule that states that higher the valency of the ion causing coagulation, greater will be its coagulating or flocculating power.
So, if a colloidal solution could be precipitated by an anion, then higher the negative charge on the anion, greater would be its flocculating power.
And, if a colloidal solution is precipitated by a cation, then higher the positive charge on the cation, greater would be its flocculating power.
The reciprocal of coagulation value is coagulation power.
$Coagulation\,power\,\alpha \,\dfrac{1}{{Coagulation\,value}}$
The given set of values is,
$NaCl$=$52$
$KCl$=$51$
$BaC{l_2}$=$0.69$
$MgS{O_4}$=$0.22$
From the given set of values, the correct order of $MgS{O_4} > BaC{l_2} > KCl > NaCl$.

So, the correct answer is Option A .

Note:
We must remember that some of the applications of flocculation are in surface chemistry, physical chemistry, civil engineering/earth science, biology, water treatment process, cheese industry and brewing. Deflocculation is the opposite of flocculation, also called peptization. An example is sodium silicate. Generally in higher pH ranges in addition to low ionic strength of solutions and domination of monovalent metal cations the colloidal particles could be dispersed. Deflocculant is the additive, which prevents the colloids from forming flocs.