Problem 39 - A Complete Resource Book in Chemistry for JEE Main

Question

Ebonite is (a) natural rubber (b) synthetic rubber (c) highly vulcanized rubber (d) polypropene

Step-by-Step Solution

Answer

(c) highly vulcanized rubber

Step 1: Understand the Options

Read through the options provided and understand what each term means in the context of rubbers. Natural rubber is harvested from rubber trees, synthetic rubber is made from petroleum, highly vulcanized rubber refers to a rubber with a lot of sulfur added to increase durability, and polypropene is a type of synthetic polymer.

Step 2: Identify Key Characteristics of Ebonite

Research or recall that ebonite is a type of rubber that is made through the process of vulcanization, where sulfur is added to the rubber and it is heated under controlled conditions. This process makes the rubber very hard and durable.

Step 3: Match Definition to Option

Match the key characteristic of ebonite being a highly vulcanized material to the option provided. Understand that this matches most closely with option (c), which indicates ebonite is highly vulcanized rubber.

Key Concepts

Natural Rubber

Natural rubber is a wonderful material derived from the sap of rubber trees, especially the Hevea brasiliensis species. This sap, also known as latex, is a white, milky liquid that is harvested by making small incisions in the bark and collecting the fluid.
Natural rubber possesses excellent elasticity, water resistance, and high tensile strength, making it ideal for a wide range of applications.

• Natural rubber is biodegradable and generally more environmentally friendly than its synthetic counterparts.
• It is widely used in products like tires, hoses, and rubber bands.

However, natural rubber can degrade over time due to environmental factors like heat, sunlight, and ozone exposure, unless it is treated or combined with other materials to improve its properties.

Synthetic Rubber

Synthetic rubber is crafted from petroleum-based monomers, offering an alternative to natural rubber. Unlike natural rubber, synthetic variations are engineered for specific characteristics and uses. There are different types of synthetic rubber, including styrene-butadiene rubber (SBR), nitrile rubber (NBR), and butyl rubber (IIR). These rubbers are developed through chemical reactions known as polymerization, where small molecules called monomers link to form larger chains known as polymers.

• Synthetic rubber generally offers better resistance to abrasion and temperature changes than natural rubber.
• It's often used in automotive parts, industrial applications, and various consumer goods.

Although synthetic rubber is not biodegradable, its tailored properties make it advantageous for numerous industrial applications.

Vulcanization Process

The vulcanization process is an essential technique used to enhance the properties of rubber, making it more durable and elastic. This method involves adding sulfur to rubber and heating it to form cross-links between the polymer chains. The result is a stronger, more stable rubber that can withstand greater stress and environmental conditions.

• Vulcanization shifts rubber from being sticky and soft to firm and elastic.
• This process is critical in producing various elastic materials, including the ebonite or hard rubber used in electric and mechanical parts.

By adjusting the amount of sulfur and the heating time, the characteristics of the vulcanized rubber can be tailored for specific applications.

Polypropene

Polypropene, also known as polypropylene, is a versatile and widely used synthetic polymer. It is produced through the polymerization of the monomer propene, a simple hydrocarbon. Polypropene is a thermoplastic, meaning it becomes pliable above a specific temperature and solidifies upon cooling.
It is known for its resistance to chemicals, toughness, and flexibility, making it an excellent material for various applications.

• Polypropene is often found in packaging, textiles, automotive parts, and consumer goods like kitchenware.
• Its light weight and strength make it a favorite material in engineering and industry.

Furthermore, polypropene is recyclable and has a lower environmental impact compared with some other plastics, contributing to its popularity in sustainable practices.