Problem 13 - A Complete Resource Book in Chemistry for JEE Main

Question

PVC as obtained after polymerization is (a) soft and pliable (b) hard, brittle and transparent (c) hard and infuseable (d) none of these

Step-by-Step Solution

Answer

(b) Hard, brittle and transparent.

Step 1: Understanding PVC

PVC, or polyvinyl chloride, is a synthetic thermoplastic material made through the polymerization of vinyl chloride. It is commonly used in applications where durability and resistance to environmental factors are required.

Step 2: Analyze the Properties of PVC

PVC is known for being a rigid material that can be either rigid or flexible depending on the addition of plasticizers. Without plasticizers, PVC exhibits hardness and slight brittleness but remains transparent, which is typical for many commercial applications before any additives.

Step 3: Determine the Correct Characteristics

Based on understanding PVC's natural properties post-polymerization and without plasticizers, it aligns most closely with being hard, brittle, and transparent.

Key Concepts

Synthetic Thermoplastic

Polyvinyl chloride, or PVC, is a fascinating example of a synthetic thermoplastic. But what exactly does that mean? Let's break it down. A synthetic material is one that is man-made, crafted through chemical processes rather than occurring naturally. Thermoplastics, on the other hand, are a type of plastic that becomes soft when heated and hard when cooled. This process can be reversible, allowing thermoplastics to be reshaped multiple times.

In the context of PVC, its synthetic nature comes from its creation in a laboratory setting through artificial means. As a thermoplastic, PVC can be heated to form various shapes and cooled to maintain its form, making it incredibly versatile. Industries often take advantage of these properties to produce everyday items like pipes, cables, and flooring. Its adaptability and resilience ensure that PVC continues to be a popular choice for many products.

Polymerization Process

The polymerization process is a crucial scientific technique used to create polymers, such as polyvinyl chloride (PVC). So, how does this process work? At its core, polymerization involves the linking of small molecules called monomers to form long, repeating chains, resulting in a polymer.

For PVC, the monomer used is vinyl chloride. Under specific conditions of temperature and pressure, along with initiators that kickstart the reaction, these vinyl chloride molecules connect.

• This chain reaction results in the creation of PVC.
• The process requires careful control to ensure the polymer has the desired attributes, like rigidity and durability.

The final product, polyvinyl chloride, emerges with a set of qualities ideal for various industrial uses, linking all those vinyl chloride molecules into one impressive polymer.

Vinyl Chloride

Vinyl chloride is the essential building block of PVC. It is a colorless gas with a slight, sweet odor and acts as the monomer in the creation of polyvinyl chloride. Its chemical formula is C extsubscript{2}H extsubscript{3}Cl, signifying its simple but effective molecular structure.

During the production phase of PVC, vinyl chloride molecules undergo polymerization, where they combine to form the long chains that make up polyvinyl chloride. Important safety notes about vinyl chloride include:

• It is highly flammable.
• Extreme care is needed during handling.

The role of vinyl chloride is vital, as it determines the structural basis upon which the properties of PVC, such as strength and flexibility, depend. By understanding these fundamentals, we gain insight into why PVC exhibits its well-known traits.