Problem 33 - Chemistry: Principles and Reactions

Question

Which of the following monomers could form an addition polymer? A condensation polymer? (a) \(\mathrm{C}_{2} \mathrm{H}_{6}\) (b) \(\mathrm{C}_{2} \mathrm{H}_{4}\) (c) \(\mathrm{HO}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{OH}\) (d) \(\mathrm{HO}-\mathrm{CH}_{2}-\mathrm{CH}_{3}\)

Step-by-Step Solution

Answer

Answer: - Monomer (a) cannot participate in either addition or condensation polymerization. - Monomer (b) can participate in addition polymerization. - Monomer (c) can participate in condensation polymerization. - Monomer (d) can participate in condensation polymerization.

Step 1: Understand Addition and Condensation Polymerization

Addition polymerization is a process where monomers containing double bonds combine to form a larger molecule without losing any atoms. Condensation polymerization, on the other hand, involves the combination of two monomers with the elimination of a small molecule (often water).

Step 2: Analyze Monomer (a)

Molecule (a) is \(\mathrm{C}_{2} \mathrm{H}_{6}\). This molecule has a single bond between the carbon atoms and no functional groups that can undergo polymerization reactions. Therefore, it cannot participate in either addition or condensation polymerization.

Step 3: Analyze Monomer (b)

Molecule (b) is \(\mathrm{C}_{2} \mathrm{H}_{4}\). This molecule contains a double bond between the carbon atoms, which allows it to participate in addition polymerization reactions. There are no functional groups present that would allow it to undergo condensation polymerization.

Step 4: Analyze Monomer (c)

Molecule (c) is \(\mathrm{HO}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{OH}\). This molecule contains two hydroxyl groups, one on each end of the molecule. These functional groups can participate in condensation polymerization reactions, but there are no double bonds present for addition polymerization.

Step 5: Analyze Monomer (d)

Molecule (d) is \(\mathrm{HO}-\mathrm{CH}_{2}-\mathrm{CH}_{3}\). This molecule contains one hydroxyl group at one end, which can participate in condensation polymerization reactions. However, it lacks any double bonds and cannot undergo addition polymerization.

Step 6: Summarize the Results

Based on our analysis: - Monomer (a) cannot form either an addition or condensation polymer. - Monomer (b) can form an addition polymer. - Monomer (c) can form a condensation polymer. - Monomer (d) can form a condensation polymer.

Key Concepts

addition polymerization

Addition polymerization is a fascinating chemical process that transforms small monomers into long-chain polymers. In this method, monomers with double or triple bonds join together to form a larger compound. Importantly, no atoms are lost or removed during this process. This makes it a clean and efficient method for creating polymers.
For example, consider the monomer ethylene (\(\mathrm{C}_{2} \mathrm{H}_{4}\)). It contains a double bond between the carbon atoms. During addition polymerization, free radicals, heat, or catalysts can break this double bond, allowing the monomer units to link together in a repeating pattern. As a result, a vast and flexible polymer chain forms.

• Common materials produced via addition polymerization include polyethylene, polypropylene, and PVC.
• The process is generally fast and useful for large-scale production.

Understanding this process is key to grasping how everyday items like plastic bags and bottles are made and why they have specific properties.

condensation polymerization

Condensation polymerization is another essential polymer-making process. Here, monomers bond together to form polymers, but unlike addition polymerization, a small molecule like water is released as a byproduct. This usually involves monomers with two functional groups such as alcohol, amine, or carboxylic acid.
For instance, consider the monomer glycol (\(\mathrm{HO}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{OH}\)), which contains two hydroxyl groups. In condensation polymerization, these groups react with complementary groups, often resulting in the formation of ester or amide bonds. Water is typically released as a side product. This process results in versatile polymers known for their durability and resistance.

• Key products from condensation polymerization include nylon, polyester, and some biodegradable plastics.
• The slow and controlled process is ideal for specialty and high-strength materials.

This detailed understanding can help explain why these polymers are chosen for specific applications like fabrics and engineering plastics.

monomers analysis

Analyzing monomers to understand their potential in polymer formation is crucial. Each type of polymerization requires monomers with specific structural features:
1. **Addition Polymerization**: Requires monomers with multiple bonds (like double bonds) for the polymer chains to form. For instance, ethylene, with its double bond, fits this criterion perfectly.
2. **Condensation Polymerization**: Needs monomers with at least two functional groups capable of reacting and releasing a small molecule. Molecules like glycols or amino acids are common in this process.

• Monomer \(\mathrm{C}_{2} \mathrm{H}_{6}\) was insufficient for both types due to lacking both multiple bonds and reactive functional groups.
• Monomer \( \mathrm{C}_{2} \mathrm{H}_{4}\) was perfect for addition polymerization owing to its double bond.
• Monomer \( \mathrm{HO}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{OH}\) could participate in condensation polymerization due to its reactive hydroxyl groups.
• Monomer \( \mathrm{HO}-\mathrm{CH}_{2}-\mathrm{CH}_{3}\) had a single hydroxyl, making it fitting for condensation polymerization but not addition.

This monomer evaluation helps in selecting the right polymerization technique to achieve desired properties in the resulting polymer. This foundational knowledge is invaluable for chemistry students seeking to understand material sciences.