Question

On which of the following properties does the coagulating power of an ion depend ?

• A. The sign of charge on the ion alone
• B. The magnitude of the charge on the ion alone
• C. Both magnitude and sign of the charge on the ion
• D. Size of the ion alone

Answer 1

The Correct Option is C

The coagulating power of an ion is crucial in the process of coagulation, where colloidal particles aggregate to form larger particles. This process can be explained by the Schulze-Hardy rule, which states that the coagulating power of an ion is dependent on the magnitude and the sign of the charge on the ion. Let’s explore this in detail:

1. Magnitude of Charge: The coagulating power increases with an increase in the valency of the ion that causes coagulation. For example, trivalent ions like Al^{3+} have more coagulating power than divalent ions like Ca^{2+}, and monovalent ions like Na^{+}. This is because higher-charged ions can neutralize the charge on colloidal particles more effectively.
2. Sign of Charge: The ion’s charge must be opposite to that on the colloidal particles for effective coagulation. If the colloidal particles are negatively charged, positively charged ions will have coagulating power, and vice versa.

Given these considerations, both the magnitude and the sign are crucial for determining the coagulating power, as they collectively decide the effectiveness of coagulation.

Thus, the correct answer is: Both magnitude and sign of the charge on the ion.