Question

Explain the effect of (i) zeta pontential, (ii) Hamaker constant and (iii) molar salt concentration on the colloid stability.

Answer 1

Colloidal solution is solution which contains microsolid substace disperse in the other liquid substance called dispersion medium. It also called colloidal suspension.

Due to two other phases it need some stability testing such as-

I- Zeta potential- the potential difference that exists between the surface of a solid particle when it is immersed in a conducting solvent or fluid such water and the bulk of the solvent. It must be within the limit to found a good effect on the stability of colloidal solution.

Zeta potential [mV] Stability behavior of the colloid

from 0 to ±5, Rapid coagulation or flocculation

from ±10 to ±30 Incipient instability

from ±30 to ±40 Moderate stability

from ±40 to ±60 Good stability

more than ±61 Excellent stability

ii Hamaker constant-The Hamaker constant A can be defined primarily for Van der Waals (VdW) body–body interaction. The force that operates between the particles or bonds make the solution stable.

III molar salt concentration - it is also one of the most important parameter for colloidal solution. Equilibrium must be maintain in a stoichiometric molar concentration. if the molar concentration is more it may lead to Aggregragation and at very low molar concentration it may lead to DEFFLUCULATIion.