CC08 — Organic Compounds & Polymers

📖 CC08 · CDS General Science — Chemistry

From everyday plastics to DNA in every cell — polymers and biomolecules shape all of modern life. CDS tests the monomer, polymerisation type, and key uses of common synthetic polymers, and the broad categories of biomolecules.

📌 CDS Focus: Addition polymerisation (polyethylene, PVC, Teflon) vs condensation (Nylon, Polyester, Bakelite); natural polymers (starch, cellulose, natural rubber); biomolecules (carbohydrates → glucose; proteins → amino acids; fats → glycerol + fatty acids). The monomer of Teflon (tetrafluoroethene) and Nylon-6,6 are direct CDS questions.

1. Types of Polymerisation

▶ Addition Polymerisation

Monomers join by opening a double bond — no byproduct released
Requires unsaturated (alkene) monomers
Product: same composition as monomer, just much larger
Examples: Polyethylene (PE), PVC, Teflon, Polystyrene, Polypropylene

▶ Condensation Polymerisation

Two different monomers join with elimination of a small molecule (H₂O, HCl, etc.)
Requires monomers with two functional groups each
Produces a chain with a different composition from monomers
Examples: Nylon-6,6; Polyester (Terylene/Dacron); Bakelite; Silk; Proteins

2. Important Polymers

Fig. 1 — Synthetic Polymers: Monomer, Polymerisation Type and Uses

3. Natural Polymers & Biomolecules

CategoryMonomer / UnitExamples & Function CarbohydratesMonosaccharides (glucose)Glucose (energy); Starch (plant storage); Cellulose (cell walls, dietary fibre); Glycogen (animal storage) ProteinsAmino acids (20 types; joined by peptide bonds)Enzymes (catalysts); Haemoglobin (O₂ transport); Antibodies (immunity); Keratin (hair, nails); Collagen (connective tissue) Fats & OilsGlycerol + 3 fatty acids (triglycerides)Energy reserve (9 kcal/g); carrier of fat-soluble vitamins (A,D,E,K); thermal insulation; cell membrane component Natural RubberIsoprene (2-methylbuta-1,3-diene)Tyres, gloves, erasers; vulcanised with sulfur to improve strength CelluloseGlucose (β-linked)Plant cell walls; paper, cotton; humans cannot digest (dietary fibre) StarchGlucose (α-linked)Food storage in plants (rice, wheat, potato); turns blue-black with iodine (test for starch)

📝 CDS PYQs — Organic Compounds & Polymers

Q1. The monomer of Teflon is: CDS PYQ

(a) Ethene(b) Vinyl chloride(c) Tetrafluoroethene(d) Styrene

✔ Answer: (c) Tetrafluoroethene (C₂F₄)

Teflon (PTFE — polytetrafluoroethylene) is made by addition polymerisation of tetrafluoroethene (C₂F₄). The C—F bonds are extremely strong and non-polar, making Teflon chemically inert, heat-resistant, and non-sticky. Used in non-stick cookware coatings and lab equipment.

Q2. Nylon is an example of: CDS PYQ

(a) Addition polymer(b) Natural polymer(c) Condensation polymer(d) Biopolymer

✔ Answer: (c) Condensation polymer

Nylon-6,6 is formed by condensation polymerisation of hexamethylenediamine and adipic acid, eliminating water at each step. Condensation polymers are formed from two different monomers with elimination of small molecules. Addition polymers (like polyethylene, PVC, Teflon) use a single monomer and open a double bond.

Q3. The building blocks (monomers) of proteins are: CDS PYQ

(a) Monosaccharides(b) Fatty acids(c) Amino acids(d) Nucleotides

✔ Answer: (c) Amino acids

Proteins are polymers of amino acids joined by peptide bonds (—CO—NH—). There are 20 naturally occurring amino acids. Protein function depends on the sequence and 3D folding. Monosaccharides are monomers of carbohydrates; fatty acids + glycerol form fats; nucleotides are monomers of DNA/RNA.

🧠 Quick Memory Chart — CC08

⚛ Addition Polymers

Polyethylene: ethene → bags, bottles
PVC: vinyl chloride → pipes, cables
Teflon: C₂F₄ → non-stick pans
No byproduct; same composition

⚛ Condensation Polymers

Nylon: two monomers, releases H₂O
Polyester: PET bottles, clothing
Bakelite: phenol+formaldehyde
Proteins & DNA: natural condensation

🐑 Biomolecules

Carbs: glucose units; starch → iodine blue
Proteins: amino acids; enzymes, Hb
Fats: glycerol + fatty acids
Rubber: isoprene; vulcanised with S

📝 Practice Exercise

E1. Which test is used to identify starch?

(a) Benedict's test(b) Iodine test (blue-black colour)(c) Biuret test(d) Fehling's test

E2. Bakelite was the first commercial:

(a) Natural polymer(b) Synthetic polymer (plastic)(c) Biopolymer(d) Rubber

E3. Vulcanisation of rubber involves treating it with:

(a) Nitrogen(b) Chlorine(c) Sulfur(d) Phosphorus

Answers: E1 → (b) Iodine test [starch turns blue-black; useful field test for starch presence] | E2 → (b) Synthetic polymer [Bakelite = phenol + formaldehyde; first fully synthetic plastic, 1907] | E3 → (c) Sulfur [sulfur cross-links polymer chains, making rubber harder and more elastic]

📝 Mock Tests 🎯 Subject Quizzes ✈️ Telegram