Conversion of freshly prepared precipitate into the colloidal solution is known as

Peptization

The correct answer is option 4. Peptization.

Let us delve into each term and focus on peptization in detail:

1. Coagulation

Coagulation is the process by which colloidal particles aggregate and form larger particles or a precipitate, typically induced by adding an electrolyte or a flocculating agent.

Mechanism: In a colloidal system, particles are usually stabilized by electrostatic repulsion or steric stabilization. When an electrolyte is added, it neutralizes the charge on the colloidal particles, reducing their repulsion and allowing them to stick together and form larger aggregates or precipitates.

Outcome: Coagulation leads to the destabilization of the colloidal system and the formation of a precipitate, which is the opposite of converting a precipitate into a colloidal solution.

2. Electrolysis

Electrolysis is a chemical process that uses electric current to drive a non-spontaneous chemical reaction. It is used in various applications, including the extraction of metals, electroplating, and the decomposition of compounds.

Mechanism: In electrolysis, an electric current is passed through an electrolyte solution, causing chemical reactions at the electrodes and leading to the formation of different substances.

Relevance: Electrolysis is not related to the conversion of a precipitate into a colloidal solution and is unrelated to the processes involving colloids.

3. Diffusion

Diffusion is the process by which particles move from an area of higher concentration to an area of lower concentration due to random thermal motion.

Mechanism: Diffusion is a fundamental process in various systems, including gases, liquids, and even colloidal systems, but it describes the movement of particles rather than their conversion into a colloidal state.

Relevance: While diffusion can affect the distribution of particles in a colloidal solution, it does not specifically address the conversion of a precipitate into a colloidal solution.

4. Peptization

Peptization is the process of converting a precipitate into a colloidal solution. It involves adding a dispersing agent or electrolyte to the precipitate to break it down into smaller particles that remain suspended in the solution as a colloidal dispersion.

Mechanism: In peptization, a dispersing agent or electrolyte interacts with the precipitate to overcome the attractive forces between the particles, reducing their aggregation. This allows the particles to disperse and stabilize as a colloidal system.

Application: Peptization is often used in various industrial and laboratory processes to produce colloidal solutions from solid precipitates. For example, when a precipitate of metal hydroxides is treated with an electrolyte or a surfactant, the precipitate can be dispersed into a colloidal solution.

Summary

Peptization is the correct term for the process of converting a freshly prepared precipitate into a colloidal solution. It involves breaking down the precipitate into smaller particles and stabilizing them in a dispersed state within the solution. This is achieved by adding a dispersing agent or electrolyte that prevents the particles from aggregating and helps them remain suspended in the solution as a colloidal system.