Problem 3 - Arihant Objective Approach to Organic Chemistry for IIT JEE and NEET all Medical Entrances Part 4

Question

Natural rubber is a polymer of : (a) butadiene (b) ethyne (c) styrene (d) isoprene

Step-by-Step Solution

Answer

Natural rubber is a polymer of isoprene (option d).

Step 1: Understand Polymers

Polymers are large molecules made up of repeating smaller units known as monomers. In natural rubber, these monomers are specific types of hydrocarbons.

Step 2: Know About Natural Rubber

Natural rubber is an elastic substance obtained from the latex sap of trees. Its primary monomer is isoprene, a hydrocarbon with the formula C5H8.

Step 3: Identify the Monomer

Among the given options, identify the correct monomer that makes up the polymer of natural rubber. We know that natural rubber primarily consists of repeating units of isoprene.

Step 4: Match Monomer with Option

Match the monomer, isoprene, with the options provided: - (a) butadiene - (b) ethyne - (c) styrene - (d) isoprene It is clear that option (d) isoprene is the correct match.

Key Concepts

Natural Rubber

Natural rubber is an intriguing material that is both highly elastic and water-resistant. It is derived from the latex sap of rubber trees, primarily the Hevea brasiliensis. When this milky sap is harvested, it can be processed and solidified into the flexible material we recognize as rubber.
Natural rubber is unique due to its ability to stretch and then return to its original shape, a property that makes it invaluable for a wide array of applications, from tires to footwear. This elasticity is a result of the polymerization of isoprene, a hydrocarbon compound, into long chains that form the rubber material.
Understanding natural rubber not only helps in comprehending its mechanical attributes but also its role in both traditional craftsmanship and modern technology. One must consider factors such as temperature and chemical exposure that can affect its properties. Its natural origins also mean it is biodegradable, but it has physical characteristics that can be modified for specific needs in industries.

Isoprene

Isoprene is the primary building block of natural rubber. Chemically, it is a hydrocarbon with the formula C5H8, consisting of carbon and hydrogen atoms. This small molecule is classified as a monomer, a foundational unit that joins with others to form polymers.
In nature, isoprene is produced by many plants and even some animals, serving various biological purposes. However, its significance in polymer chemistry lies in its capacity to form polyisoprene through a process called polymerization, where multiple isoprene units link together into long chains.

• This natural polymerization process results in the elastic properties of rubber.
• It is the repeating double-bonded carbon structure of isoprene that gives rubber its flexibility and resilience.

Isoprene is also used synthetically to produce other materials like synthetic rubber, demonstrating its versatility in material science.

Monomers

Monomers are fundamental to understanding how polymers, like natural rubber, are formed. These are small, simple molecules that bond together in chains to create larger complex structures.
In the context of natural rubber, isoprene acts as the monomer. The process involves repetitive chemical reactions, where the double bonds in isoprene molecules open up, allowing them to connect into long, chain-like molecules called polymers.

• This process transforms separate, simple monomers into a material with entirely new properties.
• The length and arrangement of these polymer chains determine the physical characteristics of the final material, such as elasticity or tensile strength.

Understanding monomers like isoprene gives insight into the molecular foundation of many everyday materials. It highlights the interplay between chemistry at a micro-level and the tangible properties we encounter at a macro level. Mastery of monomer concepts is crucial for anyone delving into polymer chemistry.