Question

Assertion: Lower is the gold number of a protective colloid, higher is its protective power. Reason: Gold number gives an identification of the charge on a colloidal solution of Protective Colloid.

Short answer

Assertion is true; Reason is false.

Step-by-step solution

Understand the Gold Number

The gold number is a term related to colloidal solutions. It measures the minimum amount (in milligrams) of a protective colloid necessary to prevent the coagulation (precipitation) of a sol in an electrolyte solution. The smaller the gold number, the more effective the protective power of the colloid.

Recognize the Aim of Protective Colloids

Protective colloids are substances that, when added to a colloidal solution, help preserve its stability by preventing coagulation. The primary goal of a protective colloid is to stabilize the colloidal particles against the effects of electrolytes.

Analyze the Assertion

The assertion states that a lower gold number means higher protective power. Since a lower gold number indicates that a smaller amount of the colloid is needed to prevent coagulation, it suggests that the colloid is highly effective at stabilizing the solution.

Understand the Reason

The reason claims that the gold number shows the identity of the charge on the colloidal solution of a protective colloid. However, the gold number actually measures protective efficiency and not the charge. Hence, this statement about charge identification is incorrect.

Conclude Based on Analysis

The assertion is true because the lower the gold number, the higher the protective power of the colloid. However, the reason is false because the gold number does not provide information about the charge of the colloidal solution.

Key concepts

Gold Number

The concept of the gold number is essential in understanding colloidal systems. It is used to evaluate the effectiveness of a protective colloid by measuring the smallest amount required to prevent coagulation in a colloidal solution. Imagine you have a colloidal gold solution. If an electrolyte is added and a protective colloid is present, it will keep gold particles from clumping together. The gold number is this minimum amount in milligrams, making it a direct indicator of a colloid's protective ability. A lower gold number means that less of the colloid is needed, indicating higher protective power. Therefore, colloids with a small gold number are excellent at stabilizing colloidal particles.

Protective Colloids

Protective colloids are crucial in maintaining the stability of colloidal solutions. They are added to prevent the particles within the colloid from clumping together due to the effects of electrolytes. Understanding their function is vital for any colloidal chemistry application. When added, protective colloids form a layer around the particles in a solution. This layer acts as a barrier that prevents particles from aggregating. Their role is to keep colloids stable in various conditions, thus making processes like paint formulation and food production feasible. Protective colloids are an essential armor that maintains the integrity of colloidal dispersions.

Stability of Colloids

The stability of colloids is a fundamental aspect of colloidal chemistry. Colloids must remain evenly dispersed without settling or clumping. This stability can be affected by factors such as the presence of electrolytes, pH levels, and temperature changes. To achieve stability, particles are often charged or stabilized by protective colloids. Charged particles repel each other, aiding in their even distribution in a solution while protective colloids provide a physical barrier against aggregation. Ensuring stability is crucial for a variety of industries, like pharmaceuticals and food, where uniformity and texture are key.

Coagulation of Colloids

Coagulation refers to the process of particles in a colloidal solution aggregating to form larger particles and eventually precipitate out. In colloids, this can happen when the electric charge on dispersed particles is neutralized, often by adding electrolytes. The neutralization causes particles that once repelled each other to stick together. When protective colloids are absent, coagulation can occur readily, disrupting the stability of the colloid and leading to separation. Understanding coagulation is necessary to control and prevent it, especially in applications requiring stable colloidal suspensions, such as in water purification and waste treatment processes.