Question

Lyophilic sols are more stable than lyophobic sols because the particles (1) are positively charged (2) are negatively charged (3) are solvated (4) repel each other (5) are heavy (a) 2,3 and 4 (b) 2 and 3 (c) 1,2 and 5 (d) 3 only

Short answer

Option (d) 3 only; lyophilic sols are stable because they are solvated.

Step-by-step solution

Understanding Lyophilic Sols

Lyophilic sols are colloidal particles that have a strong affinity for the solvent they are in. This characteristic contributes greatly to their stability. In lyophilic sols, particles are usually solvated, meaning they are surrounded or 'coated' by solvent molecules.

Identifying Key Characteristics

From the given options, being solvated is the key characteristic that significantly contributes to the stability of lyophilic sols. This process creates a protective layer around the particles, preventing them from aggregating easily.

Analyzing Stability Factors

The stability of colloidal solutions can be influenced by several factors, including solvation (being surrounded by solvent). For lyophilic sols, solvation is the most crucial factor because it reduces the surface energy and enhances stability.

Selecting the Correct Option

Considering that the stability of lyophilic sols largely arises from their solvation, option (d) 3 only, which indicates that the particles are solvated, accurately represents why lyophilic sols are more stable.

Key concepts

Colloidal Particles

Colloidal particles are tiny particles ranging in size from 1 to 1000 nanometers. These particles are dispersed throughout a medium, which can be a liquid, solid, or gas. This dispersion creates what we know as a colloidal solution, characterized by its ability to scatter light.
Colloidal particles are distinct due to their intermediate size, sitting between the smaller particles of a true solution and the larger particles of a suspension. These micro-particles are not easy to see with the naked eye, but their presence makes a big impact on the properties of the colloidal solution.
Unlike particles in a true solution, colloidal particles do not settle out upon standing. This is due to their small size and the constant bombardment of solvent molecules, a phenomenon known as Brownian motion. The stability and unique behavior of colloids are largely due to these key characteristics:

• Ability to remain suspended in the medium
• Exhibit Tyndall effect - scattering of light
• Stable against coagulation due to electrostatic charges or solvation

Understanding colloidal particles is fundamental in exploring the stability mechanisms within different types of sols.

Solvation

Solvation is the process by which solvent molecules surround and interact with solute or colloidal particles. In a lyophilic sol, this process is particularly significant because it leads to the formation of a stable colloidal solution. When particles within a colloid are solvated, they attract and retain a layer of solvent molecules.
This layer acts like a shield, protecting colloidal particles from aggregating or clumping together. Think of it as each particle having its own personal armor of solvent. This armor reduces the possibility of particles coming together and forming a bulk phase.
Important aspects of solvation include:

• The solvation shell: A protective layer of solvent molecules
• Enhanced particle stability: Promotes dispersion and avoids aggregation
• Coulombic and van der Waals forces: Facilitate the strong interaction between solvent molecules and particles

Solvation is essential not just for the stabilization of lyophilic sols but also provides insights into the behavior of molecules at interfaces, affecting their functionality in various applications.

Colloidal Solution Stability

The stability of colloidal solutions is a crucial aspect that determines their usefulness and applicability in various fields. Stable colloids do not coagulate or precipitate over time, allowing them to maintain their properties and functionality. This is especially true for lyophilic sols, which are inherently more stable due to their affinity for the solvent.
Several factors influence the stability of a colloidal solution:

• Solvation: The primary factor for lyophilic sols, where the solvent acts as a protective layer.
• Electrostatic stabilization: Arises when particles acquire charge, creating a repulsive force that prevents them from coming together.
• Hydration and steric stabilization: Involve the surface chemistry of particles and how molecular structures prevent aggregation.

By understanding these stability factors, we can better design and utilize colloidal solutions for various technological and medical applications. For lyophilic sols, maintaining their stability means ensuring that the solvation process is effective and continuous.