Question

The amount of electrolytes required to coagulate a given amount of $AgI$ colloidal solution (negative charge) will be in order:
A.${\text{NaN}}{{\text{O}}_{\text{3}}}{\text{ > Al(N}}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{3}}}{\text{ > Ba(N}}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{2}}}$
B.${\text{Al(N}}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{3}}}{\text{ > Ba(N}}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{2}}}{\text{ > NaN}}{{\text{O}}_3}$
C.${\text{Al(N}}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{3}}}{\text{ > NaN}}{{\text{O}}_3}{\text{ > Ba(N}}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{2}}}$
D.${\text{ NaN}}{{\text{O}}_3}{\text{ > Ba(N}}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{2}}}{\text{ > Al(N}}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{3}}}{\text{ }}$

Answer 1

Electrolytes: The molecules which conduct electricity due to dissociation of substance into positively charged ions and negative charged ions, are known as electrolytes.
Coagulation: It is defined as the process in which the chemicals are added in the water which causes the small particles in the water to clump. The chemicals which are added for the coagulation are known as electrolytes.

Complete step by step answer:
First of all we will talk about colloidal particles, dispersed and dispersion mediums.
1.Colloidal mixtures: It is defined as the mixture in which the tiny particles are suspended throughout another substance.
2.Dispersion phase: The phase in which the colloidal particles exist, are known as dispersed phases.
3.Dispersion medium: The medium in which the colloidal particles are distributed, is known as dispersion medium.
4.There are two types of electrolytes known as: strong electrolyte and weak electrolyte.
Strong electrolyte: The electrolytes which are completely ionized into ions on dissociation, are known as strong electrolytes.
Weak electrolytes: The electrolytes which are partially ionized into ions on dissociation, are known as weak electrolytes.
5.Coagulation: It is defined as the process in which the chemicals are added in the water which causes the small particles in the water to clump. The chemicals which are added for the coagulation are known as electrolytes. The amount of electrolyte required to coagulate a given amount of colloidal solution depends on the valency of the ion having a charge opposite to the colloidal particles.
In the given question we have to coagulate $AgI$ which is negatively charged ion. So we have to use the electrolyte having positive charge. And according to Hardy Schulze law, the higher the charge of the electrolyte the higher will be its coagulating power (the tendency to coagulate the metal ion).
Now we are given with the cations: ${\text{N}}{{\text{a}}^{\text{ + }}}{\text{ < B}}{{\text{a}}^{{\text{2 + }}}}{\text{ < A}}{{\text{l}}^{{\text{3 + }}}}$ according to the charge.
So the coagulating power of these ions will be as: ${\text{N}}{{\text{a}}^{\text{ + }}}{\text{ < B}}{{\text{a}}^{{\text{2 + }}}}{\text{ < A}}{{\text{l}}^{{\text{3 + }}}}$.
So the amount required of these electrolytes will be as: ${\text{ NaN}}{{\text{O}}_3}{\text{ > Ba(N}}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{2}}}{\text{ > Al(N}}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{3}}}{\text{ }}$(as amount required is inversely proportional to the coagulating power).

Hence option D is correct.

Note:
To coagulate positively charged ions we have to use positive charge electrolytes. And for that positive charge electrolyte the coagulating power of electrolytes will be high for that electrolyte which has high positive charge.