The correct answer is option 3. \(Al_2(SO_4)_3\).
The Hardy-Schulze rule provides a qualitative explanation of the coagulating power of ions in the coagulation of colloidal solutions. Here's a detailed explanation:\
1. Greater the valence of the coagulating ion added, the greater is its power to cause precipitation:
The valence of an ion refers to the number of charges it carries. According to the Hardy-Schulze rule, ions with higher valences have a greater ability to neutralize charges on colloidal particles and, consequently, a stronger coagulating power. This is because ions with higher valences can more effectively counteract the stabilizing forces on colloidal particles.
2. In the coagulation of a negative sol \((AgI/I^–)\), the coagulation power is maximum for \(Al_2(SO_4)_3\):
For the specific case of the coagulation of a negative sol, such as \(AgI/I^-\), aluminum sulfate (\(Al_2(SO_4)_3\)) is identified as having the maximum coagulating power. This is because aluminum ions (\(Al^{3+}\)) have a high valence (3+), making them effective in neutralizing the negative charges on the colloidal particles, leading to precipitation.
3. The coagulation power is in the order: \(Al^{3+} > Ba^{2+} > Na^+\):
The order reflects the increasing valence of the coagulating ions. Aluminum ions (\(Al^{3+}\)) have the highest valence, followed by barium ions (\(Ba^{2+}\)), and then sodium ions (\(Na^+\)). Therefore, according to the Hardy-Schulze rule, the coagulating power follows the order mentioned.
In summary, the Hardy-Schulze rule provides a qualitative guideline for predicting the coagulating power of ions based on their valences. Higher-valence ions are more effective in causing the coagulation of colloidal solutions by neutralizing the charges on the colloidal particles. |
