Chapter 14.1, Problem 6SSC

Interpretation Introduction

Interpretation:

The reason why Dispersed colloidal particles stay dispersed in dispersion medium have to be described or stability of a colloid has to be explained.

Concept introduction:

A colloid is a two-phasic heterogeneous mixture where one phase is dispersed in another phase. The dispersed particles of liquid colloids move in a jerky or zig-zag, random manner. This erratic movement of colloid particles is due to the collision between particles of the dispersion medium with the dispersed particles. These collisions make the colloid stable. Again, the dispersed particles in a colloid often contain polar or charged atomic groups on their surfaces. These polar or charged surfaces attract opposite charged areas of the dispersing-medium particles resulting in the formation of electrostatic layers around the particles. These layers repel each other when the dispersed particles collide thus, the particles remain in the colloid.

Answer to Problem 6SSC

There are two reasons behind the stability of a colloid or why dispersed colloidal particles stay dispersed in dispersion medium, (i) its electrical property and (ii) some extent kinetic property or Brownian motion.

Explanation:

The particles do not settle out due to its electrical property of colloid. Each colloidal particle is surrounded by a diffuse layer, havingmainly opposite charge. A strong repulsive force between two diffuse layers prevents two colloidal particles forming an association or these diffuse layers repel each other and prevent the particles from settling or separating. Thus colloid becomes stable.

Brownian motion continuously takes the colloidal particles from one place to another and thus probability of particles to come together or aggregating is minimized. So, Brownian motionhelps to prevent the colloid particles from settling out of the mixture to make the colloid stable.

Dispersed colloidal particles stay dispersed in dispersion medium:

1. Its electrical property
2. Some extent kinetic property or Brownian motion.

Explanation of Solution

The particles do not settle out due to its electrical property of colloid. Each colloidal particle is surrounded by a diffuse layer, havingmainly opposite charge. A strong repulsive force between two diffuse layers prevents two colloidal particles forming an association or these diffuse layers repel each other and prevent the particles from settling or separating. Thus colloid becomes stable.

Brownian motion continuously takes the colloidal particles from one place to another and thus probability of particles to come together or aggregating is minimized. So, Brownian motionhelps to prevent the colloid particles from settling out of the mixture to make the colloid stable.

Conclusion

Dispersed colloidal particles stay dispersed in dispersion medium:

1. Its electrical property
2. Some extent kinetic property or Brownian motion.