Question

The capacity of an ion to coagulate a colloidal solution depends upon (a) nature of charge (b) amount of charge (c) its shape (d) both (a) and (b)

Short answer

(d) both (a) and (b)

Step-by-step solution

Understand the Nature of Charge

The coagulation of colloidal solutions is influenced by the interaction between the charge on the colloidal particles and the ions added to it. Particles in a colloidal solution typically bear a charge, and this charge helps stabilize the system. The nature of the charge on the added ions can either enhance stability or lead to coagulation, depending on whether it neutralizes or disrupts the charge of the colloid particles.

Recognize the Role of Amount of Charge

The effectiveness of an ion in coagulating a colloidal solution is also dependent on the amount of charge it carries. Ions with a higher charge can neutralize or alter the charge on multiple colloidal particles more effectively, leading to their aggregation and subsequent coagulation. This is due to the ion's increased ability to overcome the repulsive forces between like-charged particles in the colloid.

Analyze the Impact of Shape

The shape of an ion might affect its ability to approach the colloidal particles but primarily, it is the nature and amount of charge that dictate coagulation. Different shapes could influence physical interactions, but they have a minimal effect compared to the charge impact concerning coagulation.

Combine the Influences

Considering the influences of nature of charge and amount of charge together, both factors play crucial roles in the coagulation process. The charge must be of an opposite nature to the colloidal particles for coagulation to occur, and larger charges are more effective in causing coagulation due to their ability to neutralize or alter more particles.

Key concepts

Charge Neutralization

Charge neutralization is a key concept in understanding how colloidal solutions coagulate. In a colloidal solution, particles are often stabilized by the existence of like charges that prevent them from clumping together. These charges create a repulsive force that keeps the particles distributed uniformly in the solution. However, when ions of opposite charge are introduced, they can neutralize this charge.

• Opposites Attract: The ions that are added to the solution must carry a charge opposite to that of the colloidal particles. This is because opposite charges attract, leading to a neutralization of the existing charge on the particles.
• Breaking Stability: Once the charge on the particles is neutralized, the particles lose their stability and start to coagulate or clump together.

Thus, charge neutralization is essential for transforming a stable colloidal mixture into a coagulated mass.

Nature of Charge

The nature of charge on colloidal particles and added ions plays a significant role in the coagulation process. The stability of colloidal solutions often depends on the electric charge of these particles, which can be either positive or negative.

• Stabilizing Forces: Colloidal particles are stabilized by these charges, which create repulsion between similarly charged particles, preventing them from aggregating.
• Disruption of Charge: When ions with an opposite charge are introduced, they can disrupt and neutralize the existing charges on the colloid particles, leading to coagulation.

Understanding the charge nature is crucial because only ions with a charge that is opposite to the particles' charge will lead to effective coagulation.

Amount of Charge

The amount of charge carried by an ion is crucial in determining its coagulation ability. Not all ions are equally effective in neutralizing the charge of colloidal particles.

• Higher Charge, Greater Effect: Ions with a higher charge have a greater ability to neutralize colloidal charges. This is because they can overcome the repulsive forces between the colloidal particles more effectively.
• Multiplicity of Neutralization: Ions with more charge can affect more particles at once, leading to faster and more comprehensive coagulation.

Thus, the effectiveness of an ion in causing coagulation is significantly increased with the right amount of charge it bears.