Question

Write the main reasons for the stability of colloidal sols.

Answer 1

Hint: The stability of the colloidal system is defined by the particles remaining suspended in the solution at equilibrium. Stability is hindered by aggregation and sedimentation phenomena which are driven by colloid’s tendency to reduce surface energy. Reducing the interfacial tension will stabilize the colloidal system by reducing this driving force.

Complete step by step answer:
A colloid is one of the three primary types of mixtures, with the other two being a solution and suspension. Colloidal particles collide with each other due to the Brownian motion, convection, gravity and other forces. Collisions may result in coagulation of the particles and destabilization of the colloid. If a colloidal particle is brought to a short distance to another particle, they are attracted to each other by the van der Waals force. If there is no counteracting force, the particles will aggregate and the colloidal system will be destabilized. Colloidal stability is achieved due to repulsion forces balancing the attraction forces in the way similar to the stable mechanical equilibrium {if a body is disturbed it tends to return to its former position).
The reasons for the stability of colloidal sols are
Electrostatic Stabilization: It is the mechanism in which the attractive van der Waals forces are counterbalanced by the repulsive Coulomb forces acting between the negatively charged colloidal particles.
Solvation: Solvation describes the interaction of solvent with dissolved molecules. Solvation is the process of reorganizing solvent and solute molecules into solvation complexes. Solvation involves bond formation, hydrogen bonding, and van der Waals forces. Solvation of a solute by water is called hydration

Note: It is the Brownian movement that ensures the particles that are colliding with each other. This is the only phenomenon that clearly explains the random motion of sol particles and indicates that these particles are not static.