Question

Which of the following ion has minimum coagulation value and maximum coagulation power to oppositely charged sols?

Br^-
C2O4 ^2-
PO4^3-
SO4^3-​

Answer 1

Explanation:

coagulation power α 1/coagulation value

more charge, more coagulation power

so PO4^3- has maximum coagulation power and minimum coagulation value

Answer 2

PO4^3- ion has minimum coagulation value and maximum coagulation power to oppositely charged sols.

What is coagulation value?

• Minimum concentration of electrolyte(in millimoles) required to coagulate 1 L of a colloidal solution.
• Coagulation value is inversely proportional to  coagulation power

          Coagulation value ∝ 1/ Coagulation power.

Coagulation power

• Coagulation power depends on the charge of the ion.

• Coagulation power also depends on the size of the ion.

Hardy Schulze Law:

1. Ions of opposite charge bring effective coagulation of the colloid. These ions are known as coagulating ions.
2. Greater is the valency ie, greater is charge on the ion, more is the coagulating power.

Given ions                  Charge

•     Br^-                           1

• C2O4 ^2-                      2

• PO4^3-                          3

• SO4^2-​                          2

   Since, charge on PO4^3- is maximum, therefore, it has minimum coagulation value and maximum coagulation power.