Hardy Schulze Rule

Hardy Schulze Rule

Hardy Schulze rule states that the amount of electrolyte required for the coagulation of a definite amount of a colloidal solution is dependent on the valency of the coagulating ion(i.e.Coagulating ion is the ion which has the charge opposite to the charge of the colloidal particles).
Greater the valency of the flocculating or the coagulating ion, the greater its power to facilitate the coagulation.
Coagulation power order of Al³⁺, Na⁺ and Ba²⁺ is Al³⁺ > Ba²⁺ > Na⁺.

Limitations of Hardy Schulze Rule

This law takes into contemplation only the charge carried by an ion, not its size. The lesser the size of an ion, the more will be its polarizing control. Thus, Hardy-Schulze law can be modified in terms of the polarizing power of the flocculating ion. Thus, the modified Hardy-Schulze law can be stated as the greater the polarizing power of the flocculating ion added, the greater is its power to cause precipitation.