Lesson Notes By Weeks and Term v5 - Grade 12

Lesson Video

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Performance objectives

• Define and differentiate between addition and condensation polymers.
• Identify and draw monomers for specific polymers.
• Relate polymer structure to its properties.
• Discuss the environmental impact of polymers.
• Write equations for polymerization reactions.

Lesson summary

Organic chemistry is the study of carbon-containing compounds. Macromolecules, large polymers built from smaller repeating units (monomers), are essential to life and industry. This week, we will focus on the structure, properties, and reactions of polymers, specifically addition and condensation polymers, and relating their properties to their uses. Understanding polymers is crucial because they are ubiquitous in our daily lives, from the plastics in our food packaging and water bottles to the synthetic fabrics in our clothing. In South Africa, the polymer industry is a significant contributor to the economy, employing thousands of people in manufacturing, recycling, and research.

Lesson notes

2.1 Introduction to Polymers Polymers are large molecules (macromolecules) composed of repeating structural units called monomers, connected by covalent bonds. The process of joining monomers to form a polymer is called polymerization. Polymers can be classified into two main types: addition polymers and condensation polymers. 2.2 Addition Polymers Addition polymers are formed when monomers add directly to each other without losing any atoms. This usually happens with unsaturated monomers (containing double or triple bonds), typically alkenes. The double bond breaks, and the monomers join to form a long chain.

Mechanism: The double bond in the alkene monomer breaks, allowing the monomers to link together in a chain reaction.

General Formula: (Monomer)n, where 'n' represents the number of repeating monomer units.

Examples: Polyethylene (PE): Formed from ethene (ethylene) monomers. PE is used in plastic bags, food packaging, and bottles.

Polyvinyl Chloride (PVC): Formed from chloroethene (vinyl chloride) monomers. PVC is used in pipes, window frames, and flooring.

Polypropylene (PP): Formed from propene monomers. PP is used in yogurt containers, ropes, and automotive parts.

Polytetrafluoroethylene (PTFE) (Teflon): Formed from tetrafluoroethene monomers. Teflon is used in non-stick cookware.

Drawing Addition Polymers: To draw an addition polymer, show a repeating unit enclosed in brackets with a subscript 'n'. For example, polyethylene would be represented as [-CH2-CH2-]n