Question

The coagulation value in millimoles per liter of electrolytes used for the coagulation of $A{{g}_{2}}{{S}_{3}}$are as below:
$I.\text{ }NaCl=52$
$II.\ KCl=51$
$III.\text{ }BaC{{l}_{2}}=0.69$
$IV.\text{ }MgS{{O}_{4}}=0.22$
The correct order of their flocculation 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: The addition of electrolytes also known as coagulation is inversely proportional to the coagulation or flocculation value. So, the more the addition of electrolyte less will be the coagulation or flocculation value.

Complete step by step answer:
Coagulation also is known as precipitation is a process in which the colloidal particles aggregate together to change them into large-sized particles which ultimately settle as a precipitate.
When we add electrolytes the Coagulation process starts. When we add an electrolyte to a colloidal solution, the particles of the sol will take up the ions which are oppositely charged and will get neutralized. The ion responsible for the neutralization of charge on the colloidal particles is called coagulating ion or flocculation ion. The neutral particles then start to accumulate and form particles of larger size which settle down. When the concentration of the electrolyte is low, a small amount of electrolyte is added.
So, we can define the coagulation or flocculating value as the minimum amount of an electrolyte that should be added to one liter of the colloidal solution. Thus, the smaller is the coagulation value of an electrolyte greater is its coagulating or flocculating power.
So, the given data:
$I.\text{ }NaCl=52$
$II.\ KCl=51$
$III.\text{ }BaC{{l}_{2}}=0.69$
$IV.\text{ }MgS{{O}_{4}}=0.22$
$NaCl$will have the least coagulating power and$MgS{{O}_{4}}$ will have the highest coagulating power.
The order will be: $MgS{{O}_{4}}$ >$BaC{{l}_{2}}$ > $KCl$ >$NaCl$

Therefore, the correct answer is an option (a)- $MgS{{O}_{4}}$ >$BaC{{l}_{2}}$ > $KCl$ >$NaCl$

Note: The valency of the coagulating ion is the property on which the addition of an electrolyte in the solution is decided. This observation was done by Hardy and Schulze and it is called Hardy and Schulze Law.