Problem 66 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following statement is incorrect? (1) Vinyon is a copolymer of vinyl chloride and vinyl acetate (2) Saran is a copolymer of vinyl chloride and vinylidene chloride (3) Butyl rubber in a copolymer of isobutylene and isoprene (a) 1 and 2 (b) 2 only (c) 1 only (d) none is incorrect

Step-by-Step Solution

Answer

(d) none is incorrect

Step 1: Understand the Problem

We need to identify which statement among the three given polymer descriptions is incorrect. Each statement describes the composition of a different polymer.

Step 2: Analyze Statement 1

Statement 1 claims that Vinyon is a copolymer of vinyl chloride and vinyl acetate. Vinyon is indeed a copolymer, but it is commonly known as a copolymer of vinyl chloride and vinyl acetate. Therefore, this statement is correct.

Step 3: Analyze Statement 2

Statement 2 states that Saran is a copolymer of vinyl chloride and vinylidene chloride. Saran is indeed made from a copolymer of vinyl chloride and vinylidene chloride, making this statement correct.

Step 4: Analyze Statement 3

Statement 3 mentions that Butyl rubber is a copolymer of isobutylene and isoprene. This is true, as Butyl rubber is typically produced from isobutylene (the major component) and a small amount of isoprene. Hence, this statement is also correct.

Step 5: Conclusion

After analyzing each statement, we find that all three statements accurately describe the compositions of their respective polymers, meaning none of the given statements is incorrect.

Key Concepts

Understanding Copolymers

Polymers are large molecules composed of repeating subunits called monomers. When two or more different types of monomers are joined together to form a polymer, it's referred to as a copolymer. Copolymers offer the advantage of combining properties from different monomers, leading to materials with unique characteristics.

Copolymers can be classified into various types based on how the monomers are arranged within the polymer chain:

• Random copolymers: Monomers are arranged in a random sequence, without any specific order.
• Block copolymers: Different types of monomers group together in large blocks.
• Alternating copolymers: Monomers alternate in a regular pattern throughout the polymer chain.
• Graft copolymers: Chains of one monomer are attached to the backbone of another monomer.

By selecting monomers with desirable properties, copolymers can be synthesized to suit various applications, such as improved strength, flexibility, or chemical resistance.

Exploring Vinyl Chloride

Vinyl chloride is a significant monomer used predominantly in the production of polyvinyl chloride (PVC), a versatile plastic. Structurally, vinyl chloride is a compound with the formula \( ext{C}_2 ext{H}_3 ext{Cl} \), featuring a chloroethene group.

Key properties of vinyl chloride include:

• Flammability: Vinyl chloride is highly flammable and poses safety considerations during handling and processing.
• Polymerization: It polymerizes to form long chains of PVC under specific conditions of heat and pressure, catalyzed by free radicals.
• Health risks: As a gas, vinyl chloride is hazardous and must be managed in closed systems to limit exposure.

PVC, the result of vinyl chloride polymerization, is extensively used in building and construction, piping, and medical devices due to its durability and resistance to environmental degradation.

Introduction to Isobutylene

Isobutylene is a hydrocarbon with a structure of \( ext{C}_4 ext{H}_8 \), and is one of the main monomers used in the production of butyl rubber. Known for its stability and impermeability, isobutylene plays a critical role in various industrial applications.

Key points about isobutylene include:

• Properties: It is a colorless gas at room temperature and possesses a distinctively low reactivity due to the presence of a double bond.
• Polymerization: Through polymerization, isobutylene can form butyl rubber, which is inherently impermeable to gases—an essential quality for applications requiring airtight sealing.
• Versatility: When combined with a small proportion of isoprene, it creates butyl rubber, enhancing elasticity and resilience.

Due to these features, isobutylene-based polymers are prominent in industries like automotive, where they are used for tire inner linings, as well as in other fields requiring reliable sealing components.