Question

What happens when a lyophilic sol is added to a lyophobic sol? (a) Lyophilic sol is protected (b) Film of lyophobic sol is formed over lyophilic sol (c) Lyophobic sol is protected (d) Film of lyophltic sol is formed over lyophobic sol.

Short answer

Lyophobic sol is protected.

Step-by-step solution

Understanding Lyophilic and Lyophobic Sols

First, we need to understand what lyophilic and lyophobic sols are. Lyophilic sols have a strong affinity for the dispersion medium (often a liquid like water), which means they readily dissolve and stabilize in it. Common lyophilic sols include gelatin and starch. On the other hand, lyophobic sols do not have a strong affinity for the dispersion medium and tend to precipitate easily; examples include metals like gold or silver dispersed in water.

Interaction Between Sols

When a lyophilic sol is added to a lyophobic sol, the lyophilic sol can stabilize the lyophobic sol. This occurs because the lyophilic sol forms a protective layer around the particles of the lyophobic sol. This layer prevents the lyophobic particles from coagulating or aggregating, thus 'protecting' the lyophobic sol from precipitating. This phenomenon is known as the 'protection of the lyophobic sol' by the lyophilic sol.

Analyzing Options

Now, let's examine the given options in light of what we know: (a) Lyophilic sol is protected - incorrect, as it's the lyophobic sol that is protected. (b) Film of lyophobic sol is formed over lyophilic sol - incorrect, as there is no protective film formed by lyophobic sol. (c) Lyophobic sol is protected - correct, as discussed, the lyophilic sol protects the lyophobic sol. (d) Film of lyophilic sol is formed over lyophobic sol - although this is close to the actual process, it's not 'film formation' in a literal sense, but rather a stabilization process, so this is somewhat misleading.

Conclusion

Based on the analysis, we conclude that the correct answer is 'Lyophobic sol is protected' because the lyophilic sol stabilizes the lyophobic sol and prevents it from precipitating.

Key concepts

Lyophilic Sols

Let's start with understanding lyophilic sols, which are also known as solvent-loving sols. These sols frequently have a strong affinity for the dispersion medium, such as water. This means they dissolve easily and remain stable in their solvent. From a molecular perspective, lyophilic sols are quick to interact with the molecules in their medium, making them very stable and resistant to separation.
Common examples of lyophilic sols include gelatin, starch, and gum arabic. These materials can form colloidal systems where the particles are homogeneously distributed throughout the solvent.
The stability of lyophilic sols is advantageous in various applications such as food products, pharmaceuticals, and personal care products where consistent texture and distribution are important. Here's what makes lyophilic sols special:

• They are reversible sols, meaning they can easily be converted back and forth between sol and gel forms.
• They are highly stable and do not separate on standing.

Lyophobic Sols

On the opposite end of the sol spectrum, we have lyophobic sols, also known as solvent-hating sols. These sols do not easily dissolve or stabilize in the dispersion medium. Their particles tend to aggregate and precipitate out of the dispersion if left unstabilized.
Examples of lyophobic sols include metal sols like gold or silver dispersed in water. Suspensions of colloidal silver or colloidal gold are well-known lyophobic sols, known for their bright colors.
Lyophobic sols need special attention since they lack the spontaneous stability seen in lyophilic sols. They often require stabilizing agents or precise environmental conditions to remain suspended. Why are lyophobic sols challenging? Here are a few points:

• They are irreversible, meaning they require special conditions to redissolve once coagulated.
• They need protective agents to prevent precipitation.

Sol Stabilization

Sol stabilization is a key process in colloidal chemistry, particularly involving lyophobic sols. Without proper stabilization, these particles would aggregate due to their tendency to attract and collide in the medium. Here's where the magic of lyophilic sols comes into play.
Lyophilic sols stabilize lyophobic sols by forming a protective layer around their particles. This layer acts as a barrier preventing the particles from touching and clumping together. It's a delicate ballet of balance in the dispersion, where the lyophilic sol essentially safeguards the lyophobic sol.
By studying how these interactions work, scientists and engineers can enhance the stability of various colloidal systems. This knowledge is applied in industrial sectors ranging from pharmaceuticals to materials science. Sol stabilization is vital because:

• It maintains the uniform distribution of particles.
• It prevents the undesirable coagulation or precipitation of lyophobic sols.

Protection of Sols

The protection of sols is a fascinating concept where a stable lyophilic sol is used to protect a lyophobic sol. This concept showcases one of the clever strategies used in colloidal chemistry to harness the stability of one sol to benefit another.
When a lyophilic sol is introduced into a system containing a lyophobic sol, it does more than just coexist. It envelopes the lyophobic particles, reducing their tendency to aggregate and making them stable within the dispersion medium. This process is often likened to a sort of shield or armor for the lyophobic sols.
The protection mechanism is essential in prolonging the shelf life of commercial products, ensuring performance consistency. Here's what to remember about the protection of sols:

• Lyophilic sols extend the stability of lyophobic sols.
• It is a non-permanent process, flexible based on conditions and concentrations.