Question

Kinectic activity of colloidal particles in dispersion medium is called (a) electro-osmosis (b) Brownian movement (c) cataphoresis

Short answer

The kinetic activity of colloidal particles in dispersion medium is referred to as (b) Brownian movement.

Step-by-step solution

Understand the Terminologies

Electro-osmosis is the motion of liquid relative to a stationary surface under the influence of an electric field. Cataphoresis, on the other hand, is the movement of colloidal particles under the effect of an electric field. Both options a and c refer to movement induced by an external electric field, not inherent kinetic activity.

Identify the Correct Term

Brownian motion fits the description of the inherent kinetic activity of colloidal particles in a dispersion medium. It is the random motion of particles suspended in a fluid (or the mathematical model used to describe such random movements) resulting from their collision with the fast, randomly moving molecules in the fluid.

Key concepts

Kinetic Activity

Kinetic activity is a fundamental concept in understanding the behavior of particles in a fluid. It refers to the energy that particles possess due to their motion. Every particle in motion, whether in gases, liquids, or solids, has kinetic energy that contributes to this activity. In the realm of colloidal solutions, kinetic activity is crucial as it accounts for the continuous, random movement of colloidal particles within the dispersion medium.

This movement ensures that the particles remain evenly dispersed and don't settle out due to gravity. This vibrancy is observed as a dynamic and chaotic dance, which, when viewed under a microscope, is known as Brownian motion. It results from the incessant collision of particles with the molecules of the dispersion medium. These collisions induce a zigzag, unpredictable motion, vital for understanding phenomena in fields ranging from physics to biology. The intrinsic kinetic activity showcased in Brownian motion helps prevent the colloidal particles from aggregating and ultimately settling, promoting stability within the colloidal system.

Colloidal Particles

Colloidal particles are minuscule substances, typically ranging in size from 1 nanometer to 1 micrometer, that are dispersed in a medium forming a colloidal system. These systems straddle the line between a true solution, like saltwater, and a suspension, where particles can be seen with the naked eye.

Due to their small size, these particles exhibit properties that are distinct from larger particles, including the aforementioned Brownian motion. Kinetic activity in colloidal particles is particularly significant because their size falls at a point where the influence of thermal energy and gravitational forces are closely matched. This balance allows the particles to be perpetually suspended in their medium, making them neither settle like heavier particles nor dissolve entirely like true solutes. Colloidal particles form the basis of numerous products, from milk and paint to medicinal drugs, and their behavior in the dispersion medium is essential for the desired consistency and function of colloidal mixtures.

Dispersion Medium

The dispersion medium, in the context of colloids, is the substance in which colloidal particles are dispersed. It fundamentally determines the overall properties of the colloid. Common examples of dispersion mediums include water, air, and various organic solvents. The nature of the dispersion medium—be it gas, liquid, or solid—directly affects the movement and interaction of colloidal particles.

In the case of Brownian motion, it is often the liquid or gaseous medium that provides the backdrop for this kinetic activity. The medium's molecules are in constant, vigorous motion, and when they collide with the colloidal particles, they transfer energy, causing the particles to move erratically. The temperature of the dispersion medium also plays a crucial role; higher temperatures increase the energy of the medium's molecules, thus enhancing the kinetic activity of the colloidal particles. Adaptations in the medium, whether intentional or environmental, can alter the behavior and stability of the colloid, which underscores the importance of understanding and controlling the properties of the dispersion medium in colloidal science.