Problem 10 - A Complete Resource Book in Chemistry for JEE Main

Question

The migration of colloidal particle under the influence of electric field towards an electrode is known as (a) electrophoresis (b) electro-osmosis (c) Tyndall effect (d) Brownian movement

Step-by-Step Solution

Answer

The correct answer is (a) electrophoresis.

Step 1: Understanding the Terms

Before solving the problem, let's understand what each option means: (a) Electrophoresis is the movement of charged particles through a fluid under the influence of an electric field towards the opposite electrode. (b) Electro-osmosis is the movement of liquid relative to a charged surface under the influence of an electric field. (c) Tyndall effect is the scattering of light by colloidal particles in a liquid or gaseous medium. (d) Brownian movement is the random motion of particles suspended in a fluid.

Step 2: Identifying Key Information

The exercise describes the movement of colloidal particles under the influence of an electric field towards an electrode. This indicates a process where particles move due to an electric field. This key information helps identify the correct term.

Step 3: Matching Description to Term

Based on the descriptions: - Electrophoresis involves particles moving towards an electrode under an electric field, which matches the exercise description. - Electro-osmosis, Tyndall effect, and Brownian movement do not match the given scenario as they involve different processes or effects.

Step 4: Choosing the Correct Option

Since electrophoresis fits the described movement of particles toward an electrode when an electric field is applied, option (a) is the correct answer. Therefore, the migration of colloidal particles due to an electric field towards an electrode is known as electrophoresis.

Key Concepts

Understanding Colloidal Particles

Colloidal particles are tiny particles that are distributed throughout another substance. They may be found in various mediums, such as liquid, gas, or solid. These particles are larger than atoms or simple molecules but too small to be seen with the naked eye. Their size typically ranges from 1 to 1000 nanometers.
A good example of a colloidal particle is the particles in fog or milk. In these cases, the particles are suspended in air or a liquid, producing a uniform mixture.
Colloidal systems can be vital in many scientific studies, particularly in chemistry and physics. They have unique properties, like the ability to scatter light, which is known as the Tyndall effect.

• These particles can remain suspended indefinitely because of collisions with molecules in the dispersion medium.
• The interactions with surrounding molecules prevent them from settling down.

Colloids play a crucial role in numerous applications, from industrial processes to biological systems.

Exploring the Electric Field

An electric field is a region around a charged particle or object where an electric force is exerted on other charged particles. It's a fundamental concept in electromagnetism.
In simple terms, it is the space around a charged object in which another charged object experiences an electric force.
This field can be either attractive or repulsive, based on the charges of the objects involved.

• If the charges are opposite, the field can attract them towards each other.
• If the charges are alike, the field can push them apart.

The electric field is not visible but can be represented graphically using lines of force. These lines indicate the direction a positive test charge would move if placed within the field. The influence of an electric field plays a pivotal role in the process of electrophoresis. In this context, an external electric field is applied to move colloidal particles towards an electrode.

Role of the Electrode

In the context of electrophoresis, electrodes are critical components. An electrode is a conductor through which electricity enters or leaves a medium, allowing for the flow of electrical current.
They come in various forms and materials, commonly metals like copper, platinum, or graphite.
When an electric field is applied across a medium with colloidal particles, electrodes play a vital role in determining the direction of the particle's movement.

• The positive electrode, known as the anode, attracts negatively charged particles.
• The negative electrode, known as the cathode, attracts positively charged particles.

The introduction of an electric field between electrodes causes charged colloidal particles to move, facilitating processes like separation and purification.

Understanding Charged Particles

Charged particles are atoms or molecules that have gained or lost electrons, giving them a net positive or negative charge. The presence of an electric charge allows these particles to interact strongly with electric fields.
Charged particles can exist in various states, such as ions in a solution or charged colloidal particles in a fluid. These charged entities behave predictably in electric fields, moving towards the electrode with an opposite charge.

• Positive particles are known as cations and move towards the cathode, the negatively charged electrode.
• Negative particles are known as anions and move towards the anode, the positively charged electrode.

The movement of charged particles under the influence of an electric field is the essence of electrophoresis. This principle finds wide use in scientific and medical applications, where it's used for the separation and analysis of substances like DNA or proteins.