Question

The Schulze-Hardy rule states that the critical (salt) concentration required to coagulate an electrostatically stabilized suspension is inverse proportional to the 6th power of the valency of the ions. Does this rule equally apply to peri- and orthokinetic coagulation? Explain why or why not.

Answer 1

The Schulze-Hardy rule is applicable to the colloids due to the Brownian motion of the colloidal particles. Perikinetic coagulation is governed by such Brownian motions of the particles in a suspension/colloid and hence the Schulze-Hardy rule is applicable to them more appropriately. On the other hand, orthokinetic coagulation is triggered by virtue of the hydrodynamic interactions such as sedimentation or convection, which are not exactly affected by the introduction of salts to the colloid. Hence the Schulze-Hardy rule would not be equally applicable to the orthokinetic coagulation cases.