Question

Write Hardy-Sulze rules.

Write a note on Hardy–Schulze rule.

Answer 1

1. Generally, the greater the valency of the flocculating ion added, the greater is its power to cause precipitation. This is known as the Hardy–Schulze rule.
2. In the coagulation of negative sol, the flocculating power follows the following order:
   Al³⁺ > Ba²⁺ > Na⁺
3. Similarly, in the coagulation of positive sol, the flocculating power is in the following order: 
   \[\ce{[Fe(CN)_6]^{4-} > PO_4^{3-} > SO_4^{2-} > Cl^-}\]