Chapter 14.1, Problem 7SSC

Interpretation Introduction

Interpretation:

The reason behind the Brownian motion is to be explained.

Concept introduction:

Robert Brown (1773−1858), an English botanist in 1827, observed that pollen grains in aqueous suspensions were in constant motion. That time Ultra-microscope was not there, so later on ceaseless erratic and random movements of colloidal particles were observed similar to pollen grains under ultra-microscope. This random and erratic movement of colloid particles is called Brownian motion. Usually, the random movement of a particle is observed to be stronger in smaller sized particles, less viscous liquid and at a higher temperature.

Answer to Problem 7SSC

The Brownian motion is due to the bombardment or collision of colloidal particles by the particles of dispersion medium.

Explanation:

Brownian movement is observed in all colloidal solutions but not seen in true solution. As, true solution is a homogeneous solution and have smaller solute particles. Their collisions in true solutions are uniform. So, they do not show Brownian movement. The Brownian motion is due to the bombardment or collision of colloidal particles by the particles of dispersion medium. As a result, the colloidal particles acquire same amount of kinetic energy as compare to the particles of dispersion medium. Since, colloidal particles are considerably heavier than the particles of dispersion medium, their movement is considerably slower than that of the particles of dispersion medium. The Brownian motion is responsible for the stability of the colloids. That means these random collisions between colloidal particles and the particles of dispersion medium help to prevent the colloid particles from settling out of the mixture.

The Brownian motion of colloidal particles is due to the bombardment or collision of dispersed phase particles by the particles of dispersion medium.

Explanation of Solution

Brownian movement is observed in all colloidal solutions but not seen in true solution. As, true solution is a homogeneous solution and have smaller solute particles. Their collisions in true solutions are uniform. So, they do not show Brownian movement. The Brownian motion is due to the bombardment or collision of colloidal particles by the particles of dispersion medium. As a result, the colloidal particles acquire same amount of kinetic energy as compare to the particles of dispersion medium. Since, colloidal particles are considerably heavier than the particles of dispersion medium, their movement is considerably slower than that of the particles of dispersion medium. The Brownian motion is responsible for the stability of the colloids. That means these random collisions between colloidal particles and the particles of dispersion medium help to prevent the colloid particles from settling out of the mixture.

Conclusion

The Brownian motion of colloidal particles is due to the bombardment or collision of dispersed phase particles by the particles of dispersion medium.