Question

Given below are two statements
Statement I:
In the coagulation of a negative sol, the flocculating power of the three given ions is in the order $A{l}^{3+}>B{a}^{2+}>N{a}^{+}$
Statement II:
In the coagulation of a positive sol, the flocculating power of the three given salts is in the order $NaCl>N{a}_{2}S{O}_4>N{a}_{3}P{O}_4$
In the light of the above statements, choose the most appropriate answer from the options given below.

• A. Statement I is incorrect but statement II is correct
• B. Both Statement I and Statement II are correct
• C. Statement I is correct but Statement II is incorrect
• D. Both Statement I and Statement II are incorrect.

Answer 1

The correct option is C Statement I is correct but Statement II is incorrect

The required amount of electrolyte for the coagulation of a definite quantity of colloidal solution is dependent on the valency of the coagulating ion (which is the ion that holds a charge which is opposite to the charge of the colloidal particles). This observation is often referred to as the Hardy Schulze law.

• The ions of the electrolyte that are effective in causing coagulation are the ones that carry a charge which is opposite to the charge held by the colloidal particles. These ions can be referred to as flocculating ions or coagulating ions.
• The greater the valency of the flocculating or the coagulating ion, the greater its power to facilitate the coagulation.

Statement I is correct, & Statement – II is incorrect.
The flocculation power of anions is $N{a}_{3}P{O}_4>N{a}_{2}S{O}_4>NaCl$