Problem 10 - A Complete Resource Book in Chemistry for JEE Main

Question

Treatment of rubber with sulphur is (a) annealing (b) vulcanization (c) quenching (d) none of these

Step-by-Step Solution

Answer

The treatment of rubber with sulphur is vulcanization (b).

Step 1: Understanding the Question

The question is asking about a process involving the treatment of rubber with sulphur. This involves a transformation in the properties of rubber through a chemical reaction.

Step 2: Analyzing the Options

We have four options to consider: (a) Annealing: This is a heat treatment that alters the physical properties of a material, often used with metals to relieve stress. It is not typically associated with rubber. (b) Vulcanization: This is a process where sulphur is added to rubber to improve its elasticity and strength. This is directly related to rubber treatment. (c) Quenching: This is another heat-treatment process used for metals to make them harder and more brittle. It is not relevant to rubber. (d) None of these: Suggested if none of the above options were applicable.

Step 3: Identifying the Correct Answer

Based on the definitions, vulcanization is the relevant process involving sulphur that improves rubber's properties, making it more elastic and durable. Therefore, the treatment of rubber with sulphur is known as vulcanization.

Step 4: Verifying the Answer

Ensure that the answer fits the context and definitions. Vulcanization uses sulphur to change the properties of rubber, making it the appropriate choice here.

Key Concepts

Rubber Treatment

Rubber treatment refers to the processes used to enhance the properties of natural rubber, making it suitable for various applications. Natural rubber, as it is, is usually too soft and sticky for many purposes. It needs to be treated to improve properties like elasticity, strength, and heat resistance. This is where vulcanization comes into play.

Vulcanization is the most common treatment process for rubber. It involves heating the rubber with sulfur, which creates cross-links between the polymer chains, significantly altering its characteristics:

• Increased Elasticity: Vulcanized rubber can stretch more easily and return to its original shape, making it perfect for products like tires and elastic bands.
• Improved Strength: The interlinking molecules make the rubber more robust and tougher than untreated rubber.
• Enhanced Heat Resistance: Treated rubber can withstand higher temperatures without melting or deforming.

Through these changes, treated rubber becomes far more versatile and functional in everyday items.

Sulphur in Chemistry

Sulphur is a non-metal element that plays a vital role in chemistry, especially in its application in vulcanization. Known by the symbol \( S \) and holding an atomic number of 16, sulphur is known for its non-toxic, bright yellow crystals in its elemental form. However, sulphur's exciting action occurs during chemical reactions, like vulcanization, where it transforms materials on a molecular level.

In the context of rubber treatment, sulphur facilitates the formation of cross-links between rubber polymer chains. This process involves a chemical reaction between sulfur and the rubber's carbon backbone:

• These sulphur bridges between polymer molecules give the treated rubber its enhanced properties.
• The amount and type of sulphur added can adjust the rubber's hardness and flexibility.
• Vulcanization can create different sulphur bridges, like monosulfide or polysulfide, which fine-tune the material's properties.

Understanding sulphur's role in vulcanization highlights its importance in creating everyday goods with longer lasting and more durable features.

Chemical Reaction

Chemical reactions are processes where substances undergo transformation to form new materials with different properties. In the context of vulcanization, the chemical reaction between rubber and sulphur is pivotal to transforming natural rubber into a more durable material.

During vulcanization:

• The rubber and sulphur are heated together, prompting the sulphur atoms to form covalent bonds with the rubber polymer chains.
• This results in a network of cross-linked polymers that drastically change the material's properties.
• The increased molecular weight of the treated rubber contributes to its enhanced physical properties, such as flexibility and resistance to various environmental factors.

Chemical reactions like this are essential in materials science, showcasing how a simple element like sulphur can significantly enhance a natural material through precise and controlled transformations.