Using Resources

What do humans use the Earth’s resources for?

Warmth, shelter, food and transport

What are examples of finite resources?

• Crude oil for polymers and fuels

• Limestone for cement

• Metal ores to extract metals

What is an alternative synthetic product to wool?

Acrylic fibres e.g. polypropene

What is an alternative synthetic product to cotton?

Polyester

What is an alternative synthetic product to silk?

Nylon

What is an alternative synthetic product to wood?

PVC, composites e.g. MDF

What are the requirements for drinking water in the UK?

Low levels of dissolved salts and microbes

What is potable water?

Water that’s safe to drink

Why is potable water not pure in the chemical sense?

It contains dissolved substances

What do the methods used to produce potable water depend on?

• Available supplies of water

• Local conditions

How is most potable water produced?

1. Choose an appropriate source of fresh water

2. Passing the water through filter beds

3. Sterilising

What are 3 sterilising agents used for potable water?

Chlorine, ozone or ultraviolet light

When would desalination be required?

If supplies of fresh water would be limited and desalination of salty/sea water would be necessary

How can desalination be completed?

By distillation or by membrane-using processes such as reverse osmosis

Why is desalination not desirable?

Uses lots of energy

What needs to be removed from sewage and agricultural waste water so that it can be released into the environment?

Organic matter and harmful microbes

What needs to be removed from industrial waste water so that it can be released into the environment?

Organic matter and harmful chemicals

What happens during sewage treatment?

• screening and grit removal

• sedimentation to produce sewage sludge and effluent

• anaerobic digestion of sewage sludge

• aerobic biological treatment of effluent

What are some traditional methods for mining metal ores?

Digging, moving and disposing of large amounts of rock

What happens during phytomining?

• Plants absorb metal compounds

• Plants are harvested and burnt

• Ash contains metal compounds

What happens during bioleaching?

• Bacteria feed on low-grade metal ores

• The leachate is obtained from waste copper ore and contains the metal compounds

What is a low grade ore?

An ore that contains a small percentage of the metal or its compound

How can copper be obtained from solutions of copper compounds?

By displacement using scrap iron or by electrolysis

What does an LCA (life cycle assessment) carry out?

An assessment into the environmental impact of products at these stages:

• extracting and processing raw materials

• manufacturing and packaging

• use and operation during its lifetime

• disposal at the end of its useful life, including transport and distribution at each stage

Why can selective or abbreviated LCAs be misused?

Misused to reach pre-determined conclusions e.g. in support of claims for advertising purposes

What does the reduction in use, reuse and recycling of materials by end users reduce?

• Use of limited resources

• Use of energy sources

• Waste

• Environmental impacts

What are some example of items produced from limited raw materials?

• Metals

• Glass

• Building materials

• Clay ceramics

• Most plastics

What does quarrying and mining cause?

Environmental impacts as a result of obtaining raw materials

How can glass bottles be reused?

Crushed and melted to make different glass products

How can metal be recycled?

By melting, recasting or reforming into different products

What does the amount of separation required for recycling depend on?

The material and the properties required of the final product

What is corrosion? Give an example.

The destruction of materials by chemical reactions with substances in the environment. E.g. rust

What is necessary for iron to rust?

Air and water

How can corrosion be prevented?

By applying a coating that acts as a barrier:

• greasing

• painting

• electroplating

What prevents aluminium from corroding?

An oxide coating

What is sacrificial protection?

Where some coating are reactive and contain a more reactive metal to provide sacrificial protection e.g. zinc galvanises iron

What is bronze an alloy of?

Copper and tin

What is brass an alloy of?

Copper and zinc

What is gold used in jewellery an alloy of?

Silver, copper and zinc

How many carats is 100% gold?

24

What are steels?

Alloys of iron that contain specific amounts of carbon and other metals

What are the properties of high carbon steel?

Strong but brittle

What are the properties of low carbon steel?

Softer and more easily shaped

What do stainless steels contain?

Chromium and nickel

How is soda-lime glass made?

By heating sand, sodium carbonate and limestone

What is borosilicate glass made from? What are its properties?

Made from sand and boron trioxide, Melts at higher temperatures than soda-lime

How are clay ceramics, pottery and bricks made?

By shaping wet clay and heating it in a furnace

What do the properties of polymers depend on?

The monomers they’re made from and the conditions under which they’re made

What happens to thermosoftening polymers when they’re heated? Why?

They melt because they’re intermolecular forces are weak

What happens to thermosetting polymers when they’re heated? Why?

They don’t melt because of their cross-linking

What are most composites made up of?

A matrix or binder surrounding and binding together fibres of the other material, the reinforcement

What are some examples of composites?

• Plywood

• Concrete

• Fibreglass

What is the Haber process used for?

Used to manufacture ammonia which can be used to produce nitrogen-based fertilisers

What are the raw materials for the Haber process?

Nitrogen from the air and hydrogen from natural gas

What happens during the Haber process?

• Purified gases are passed over an iron catalyst at a high temperature (450°C) and a high pressure (200 atm)

• Reaction is reversible of ammonia is formed and broken down

• On cooling, the ammonia liquefies and is removed

What is the equation for the Haber process?

nitrogen + hydrogen → ← ammonia

Why is a higher pressure not used during the Haber process?

It would produce higher yields but it would be too expensive to run

Why is a higher temperature not used during the Haber process?

Lower temperatures would increase the yield but it would be produced too slowly

What are NPK fertilisers made up of?

Nitrogen, phosphorus and potassium

What are NPK fertilisers?

Formulations of various salts containing appropriate percentages of the elements

What can ammonia be used to manufacture?

Ammonium salts and nitric acid

What is phosphate rock treated with to produce soluble salts that can be used as fertilisers?

Nitric or sulphuric acid

What salt is produced when phosphate rock is treated with nitric acid?

Phosphoric acid and calcium nitrate

What salt is produced when phosphate rock is treated with sulphuric acid?

Single superphosphate, a mixture of calcium phosphate and calcium sulfate

What salt is produced when phosphate rock is treated with phosphoric acid?

Triple superphosphate (calcium phosphate)