Problem 61 - A Complete Resource Book in Chemistry for JEE Main

Question

The movement of colloidal particles towards the oppositely charged electrodes on passing electric current is known as (a) Tyndall effect (b) cataphoresis (c) Brownian movement (d) none of these

Step-by-Step Solution

Answer

(b) Cataphoresis.

Step 1: Understanding the Question

The exercise is asking about a specific phenomenon where colloidal particles move towards oppositely charged electrodes when an electric current is passed through a colloid. We need to identify the term that describes this process.

Step 2: Analyzing the Options

We will analyze each option: (a) Tyndall effect - This is a phenomenon related to the scattering of light by particles in a colloid. (b) Cataphoresis - Often another term for electrophoresis, where particles move under the influence of an electric field. (c) Brownian movement - This refers to the random motion of particles suspended in a fluid. (d) None of these - If none of the options fit, this might be the choice, but we need to check if any option matches first.

Step 3: Matching the Phenomenon to the Options

The movement of charged particles in a colloid towards oppositely charged electrodes when an electric current is applied is best described by the option (b) cataphoresis. This is another name for electrophoresis, and it fits the described phenomenon.

Key Concepts

Colloidal Particles

Colloidal particles are tiny particles that are dispersed throughout a medium, usually a liquid or a gas. These particles are significantly larger than atoms or simple molecules but still tiny enough to remain suspended without settling.
They range from approximately 1 nanometer to 1 micrometer in size.

• Due to their size, they exhibit unique properties, such as scattering light, leading to phenomena like the Tyndall effect.
• Colloidal particles can be seen in everyday items like milk, fog, and paint.
• Their behavior and interaction with light and other substances make them essential in various scientific and industrial processes.

Understanding colloidal particles is essential for grasping their movement during processes like electrophoresis, where they respond to electric fields due to their charge.

Electric Current

Electric current is the flow of electric charge through a conductor or medium. Often represented by the symbol 'I,' electric current is measured in amperes (A).
In a system involving colloids, electric current is what induces the movement of charged particles towards electrodes.

• An electric current is created by applying a voltage across a medium, causing charged particles to move.
• This movement is critical in electrophoresis, where it causes colloidal particles to drift towards oppositely charged electrodes.
• Understanding electric current's role is vital in both chemistry and physics for manipulating how charged particles behave in different environments.

Through electric current, scientific processes leverage the controlled movement of particles, enhancing techniques like separation and purification.

Charged Electrodes

Charged electrodes are conductors that have either a positive or negative charge. They are essential in processes like electrophoresis, where they attract oppositely charged particles.
These electrodes create the necessary electric field to influence particle movement.

• The positive electrode is known as the anode, while the negative electrode is the cathode.
• In electrophoresis, negatively charged particles move toward the anode, and positively charged particles move toward the cathode.
• Charged electrodes are crucial in various applications, including electrochemical cells and batteries, as they facilitate the flow of current by attracting and releasing charged particles.

The strategic use of charged electrodes enables the separation of particles in lab settings, providing an understanding of particle characteristics and reactions.