Question

Explain why particles of a colloidal solution do not settle down when left undisturbed, while in the case of a suspension, they do.

Answer 1

Colloidal solution:

1. The definition of a colloidal solution is a mixture of different kinds of particles. These particles, which are regularly suspended in a fluid and are microscopically dispersed
2. Due to Brownian motion, colloid particles resist quickly settling to the bottom of a vessel.
3. Brownian movement is the random movement of colloidal particles suspended in a liquid or gas caused by the collisions with molecules of the surrounding medium.
4. Colloids have continuously moving particles. The particles are attracted to one another strongly by intermolecular interactions.
5. However, the particles in a suspension are larger than those in a colloid, and the molecular interactions in a suspension are insufficient to keep the particles suspended, thus they settle down.

Therefore, due to the Brownian movement present in colloids particles of a colloidal solution do not settle down when left undisturbed.