4.4 Materials
Polymers - Assumed knowledge

Polymers extends the work on materials introduced in Stage 1 subtopics 1.1 and 2.1, addition polymerisation introduced in Stage 1 subtopic 3.4, and condensation polymerisation in Stage 2 subtopics 3.7 and 3.8.

Production of polymers

Polymers are produced from monomers by addition or condensation reactions.

  • Identify whether a molecule could undergo polymerisation, given its structural formula and, if so, the type of polymerisation.
  • Identify a polymer as being the product of an addition polymerisation or a condensation polymerisation, given its structural formula.
  • Identify the repeating unit of a polymer, given its structural formula.

Animated Notes

The chemistry of football shirts

Synthetic polymers

The production of synthetic polymers allows the manufacture of materials with a diverse range of properties.

  • Discuss the advantages and disadvantages of synthetic polymers.
  • Compare the effects of heating on thermoplastic and thermoset polymers.

Animated Notes

Physical properties of polymers

Organic polymers can have different properties, such as rigidity, depending on the monomers and the degree of cross-linking between chains.

  • Compare the physical properties of polymers with different degrees of cross-linking and secondary interactions between polymer chains.

Animated Notes

Polymer source materials

Polymers can be made from fossil resources or from renewable materials.

  • Discuss the advantages and disadvantages of making polymers from fossil resources or from renewable materials.

Video: Intro to Polymers (Flippin' Science)

Biodegradable polymers

Some polymers are biodegradable — being able to be broken down by microorganisms and other living things.

  • Explain why some polymers are biodegradable but others are not.
  • Explain the advantages of polymers being biodegradable.

Video: Biopolymers (Flippin' Science)

Metals - Assumed knowledge

Metals applies the concepts of reactions of acids from Stage 1 subtopic 5.2, and draws on concepts of redox, metal reactivity, and electrochemistry introduced in Stage 1 Topic 6.

Conversion of minerals for reduction

The occurrence of metals in combined or uncombined form in the Earth’s crust is related to the reactivity of the metal.

The production of some metals requires the conversion of minerals to a form suitable for reduction.

  • Explain, with the aid of equations, the methods chosen for the conversion of a mineral to a metal, given sufficient information.

Animated Notes

Video: Redox Rocks

Video: Froth Flotation demo

Methods of reduction

The method used in the reduction stage in the production of a metal is related to the reactivity of the metal and the availability of energy.

Given the position of a metal in the activity series of metals:

  • Predict whether the metal is likely to occur in nature in a combined or uncombined form.
  • Predict and explain the likely method of reduction of the metal compound, including electrolysis of the molten compound, electrolysis of an aqueous solution of the metal compound, and use of carbon as a reducing agent.
  • Explain the benefits of one method of reduction compared with another, given relevant information.

Animated Notes

Electrolytic cells

Electrolytic cells are used to produce required substances.

  • Identify the anode and cathode and their charges, as well as the direction of ion and electron flow in an electrolytic cell, given sufficient information.
  • Write electrode half-equations for an electrolytic cell, given sufficient information.

Animated Notes

Redox numbers practice
Half equation method practice
Electrolysis product practice

Recycling - Assumed knowledge

Recycling draws on concepts introduced in Stage 1 subtopics 2.1, 3.2, and 3.4.

Advantages of recycling

There is a finite amount of materials on Earth. Materials that can be recycled reduce the amount of new materials that need to be produced from the Earth’s crust.

  • Explain the advantages of recycling materials.

Video: VISY Recycling

Video: Recycling (Flippin' Science)

Video: Super Elements

Ease of recycling

Some objects are difficult to recycle.

  • Explain the difference in the ease of recycling thermoplastic and thermoset polymers.

Animated Notes

Composite materials

Composite materials comprise two or more constituent materials to produce a material with properties different from the individual components.

  • Explain the advantages using of composite materials.
  • Explain the difficulties associated with recycling materials and objects comprising two or more different materials with different properties.

Video: Recycling (Flippin' Science)

Fact Sheet: Recycle Right SA