IGCSE CHEMISTRY SECTION 5 LESSON 3

Content The iGCSE Chemistry course Section 1 Principles of Chemistry Section 2 Chemistry of the Elements Section 3 Organic Chemistry Section 4 Physical Chemistry Section 5 Chemistry in Society

Content Section 5 Chemistry in industry a)Extraction and uses of metals b)Crude oil c)Synthetic polymers d)The industrial manufacture of chemicals

Lesson 3 c) Synthetic polymers 5.15 understand that an addition polymer is formed by joining up many small molecules called monomers 5.16 draw the repeat unit of addition polymers, including poly(ethene), poly(propene) and poly(chloroethene) 5.17 deduce the structure of a monomer from the repeat unit of an addition polymer 5.18 describe some uses for polymers, including poly(ethene), poly(propene) and poly(chloroethene) 5.19 explain that addition polymers are hard to dispose of as their inertness means that they do not easily biodegrade 5.20 understand that some polymers, such as nylon, form by a different process called condensation polymerisation 5.21 understand that condensation polymerisation produces a small molecule, such as water, as well as the polymer.

The Monomer Do you remember ethene?

The Monomer Do you remember ethene? Alkene C 2 H 4

The Monomer Do you remember ethene? Alkene C 2 H 4 Unsaturated hydrocarbon because it has a double bond

The Monomer Do you remember ethene? Alkene C 2 H 4 Unsaturated hydrocarbon because it has a double bond Can be produced by the cracking of crude oil products

The Monomer Do you remember ethene? Alkene C 2 H 4 Unsaturated hydrocarbon because it has a double bond Can be produced by the cracking of crude oil products Individual ethene molecules can join together to form longer chain molecules called POLYMERS

Polymerization The process of joining single monomers together to form longer chain polymers is known as polymerization.

Polymerization The process of joining single monomers together to form longer chain polymers is known as polymerization. + Pressure Catalyst

Polymerization The process of joining single monomers together to form longer chain polymers is known as polymerization. + Pressure Catalyst

Polymerization The process of joining single monomers together to form longer chain polymers is known as polymerization. + Pressure Catalyst Single ethene molecules Polyethene molecule (or “polythene”)

Polymerization The process of joining single monomers together to form longer chain polymers is known as polymerization. + Pressure Catalyst Single ethene molecules Polyethene molecule (or “polythene”) Polyethene is a wax-like solid with an average relative molecular mass of about 30,000 – 50,000

Polymerization This process is known as addition polymerization because the polymer has the same basic formula as the monomer.

Polymerization This process is known as addition polymerization because the polymer has the same basic formula as the monomer. Polyethene is one of a large group of synthetic substances that we refer to as PLASTICS.

PLASTICS - advantages

Easily shaped and moulded, and can be extruded, injection moulded and vacuum formed

PLASTICS - advantages Easily shaped and moulded, and can be extruded, injection moulded and vacuum formed They are relatively inexpensive, being produced as a by- product of oil refining.

PLASTICS - advantages Easily shaped and moulded, and can be extruded, injection moulded and vacuum formed They are relatively inexpensive, being produced as a by- product of oil refining. They are durable, and do not rust, corrode or decay.

PLASTICS - advantages Easily shaped and moulded, and can be extruded, injection moulded and vacuum formed They are relatively inexpensive, being produced as a by- product of oil refining. They are durable, and do not rust, corrode or decay. They are lighter than steel, wood or stone.

PLASTICS - advantages Easily shaped and moulded, and can be extruded, injection moulded and vacuum formed They are relatively inexpensive, being produced as a by- product of oil refining. They are durable, and do not rust, corrode or decay. They are lighter than steel, wood or stone. They are thermal and electrical insulators.

PLASTICS - disadvantages

They are not biodegradable. This means that they do not decay naturally

PLASTICS - disadvantages They are not biodegradable. This means that they do not decap naturally Many plastics produce poisonous fumes when they burn.

Other examples of addition polymers

Propene C 3 H 6 Polypropene or polypropylene Use: washing-up bowls

Other examples of addition polymers Chloroethene (Vinyl chloride) C 2 H 3 Cl Polychloroethene or PVC Use: waterproof material

Uses for Polymers POLYMERProperties Uses

Uses for Polymers POLYMERProperties Uses Polythene Very cheap and strong. Easily moulded. Plastic bags, bottles, buckets

Uses for Polymers POLYMERProperties Uses Polythene Very cheap and strong. Easily moulded. Plastic bags, bottles, buckets Polyvinyl chloride (PVC) Forms strong waterproof sheets. Hard but flexible. Electric wire insulation, plastic sheets

Uses for Polymers POLYMERProperties Uses Polythene Very cheap and strong. Easily moulded. Plastic bags, bottles, buckets Polyvinyl chloride (PVC) Forms strong waterproof sheets. Hard but flexible. Electric wire insulation, plastic sheets Polystyrene Cheap, easily moulded. Can be expanded into foam Packaging, radio outer cases

Uses for Polymers POLYMERProperties Uses Polythene Very cheap and strong. Easily moulded. Plastic bags, bottles, buckets Polyvinyl chloride (PVC) Forms strong waterproof sheets. Hard but flexible. Electric wire insulation, plastic sheets Polystyrene Cheap, easily moulded. Can be expanded into foam Packaging, radio outer cases Polypropene Resistant to high temperatures Trays, sinks, bottles, funnels

H CH 3 C = C So that was addition polymerization. What’s all this I hear about condensation polymerization?

H CH 3 C = C So that was addition polymerization. What’s all this I hear about condensation polymerization? What’s a condensation reaction?

Condensation Reaction: “Two molecules combine with the loss of a smaller molecule, which may be water”.

Condensation Reaction: “Two molecules combine with the loss of a smaller molecule, which may be water”. The polymer does not have the same empirical formula as the monomers.

For example, nylon is made by condensation polymerization. Adipyl chloride Hexane-1,6-diamine

For example, nylon is made by condensation polymerization. Adipyl chloride Hexane-1,6-diamine Nylon Rotate

For example, nylon is made by condensation polymerization. Adipyl chloride Hexane-1,6-diamine Nylon Hexane-1,6-diamine + adipyl chloride  nylon + hydrogen chloride Rotate

End of Section 5 Lesson 3 In this lesson we have covered: The monomer Addition polymerization Condensation polymerization

H CH 3 C = C H H C C H Cl C H H C H C = C H H Cl H