[C10] Using resources

What are finite resources?

Resources that aren't formed quickly enough to be considered replaceable

What are renewable resources?

Resources that reform at a similar rate to, or faster than they are used

What are natural resources?

Resources that form without human input

What is sustainable development?

Development that meets the needs of current generations without compromising the ability of future generations to meet their own needs

What is potable water?

Water that is safe to drink

What is desalination?

The removal of salt from water

Is potable water pure?

No - it contains dissolved substances

What is the main source of fresh water in the UK?

Rain water that collects in the ground and in rivers and lakes

Outline the three steps in producing potable water from fresh water (3)

Choose a source of fresh water

Passing water through filter beds

Sterilising it

Why is fresh water passed through filter beds when making potable water?

To remove any solid material

Why is fresh water sterilised when making potable water?

To kill microbes

If supplies of fresh water are limited, how will potable water be generated?

Desalination of salt water or sea water

How is salty water desalinated? (2)

Distillation
Reverse osmosis

How can fresh water be sterilised? (3)

Chlorine

Ozone

UV light

Why is it better to generate potable water from fresh water than salty water?

Desalination of salty water requires lots of energy

How can you test if water is pure? (2)

Check the melting and boiling point

Pure water melts at 0 ᵒC and boils at 100 ᵒC

How is sewage treated? (4)

Screening to remove any large material

Sedimentation to produce sludge and effluent

Sludge undergoes anaerobic digestion to produce natural gas and fertiliser

Effluent undergoes aerobic digestion to produce water

Outline the process of sedimentation during waste treatment (3)

Sewage water stands in a settlement tank

Heavy solids sink to the bottom to produce sludge

Light effluent floats on the top

What happens when sludge undergoes anearobic digestion?

The organic matter is broken down producing natural gas and fertiliser

What happens when effluent undergoes aerobic digestion?

The organic matter is broken down producing water

What happens to the water that is produced from the aerobic digestion of effluent?

Released back into the environment

[𝗛𝗶𝗴𝗵𝗲𝗿 𝘁𝗶𝗲𝗿] What is a low grade ore?

An ore that contains only a small amount of the required metal

[𝗛𝗶𝗴𝗵𝗲𝗿 𝘁𝗶𝗲𝗿] What is an ore?

A naturally occuring compound from which a metal can be extracted

[𝗛𝗶𝗴𝗵𝗲𝗿 𝘁𝗶𝗲𝗿] Name two methods used to extract copper from low-grade copper ores

Phytomining

Bioleaching

[𝗛𝗶𝗴𝗵𝗲𝗿 𝘁𝗶𝗲𝗿] Describe the process of phytomining

- Plants absorb copper compounds from the soil containing low grade copper ore - The plants are harvested and burned to produce ash that contains copper compounds

[𝗛𝗶𝗴𝗵𝗲𝗿 𝘁𝗶𝗲𝗿] Describe the process of bioleaching

- Bacteria feed on copper compounds in low grade copper ores - Bacteria produce leachate that contains copper compounds

[𝗛𝗶𝗴𝗵𝗲𝗿 𝘁𝗶𝗲𝗿] What is leachate?

A solution of soluble copper compounds

[𝗛𝗶𝗴𝗵𝗲𝗿 𝘁𝗶𝗲𝗿] How is copper extracted from the soluble copper compounds produced in bioleaching and phytomining? (2)

Electrolysis
Displacement reactions using scrap iron

[𝗛𝗶𝗴𝗵𝗲𝗿 𝘁𝗶𝗲𝗿] What are the advantages of obtaining copper from bioleaching or phytomining instead of traditional mining?

They don’t involve digging, moving and disposing of large amounts of rock

Why are life cycle assessments carried out?

To assess the environmental impact of the life of a product

What are the main stages of a life cycle assessment? (4)

Consider the environmental impact of products during: 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

What are ceramics?

Non-metal solids with high melting points that aren't made from carbon-based compounds

What are two examples of ceramics?

Glass

clay ceramics

Name two types of glass

Soda-lime glass

borosilicate glass

What is soda-lime glass made from?

Sand, limestone and sodium carboante

What is borosilicate glass made from?

Sand and boron trioxide

How is glass formed?

The components of hte mixture are heated until they melt, when the mixture cools it comes out as glass

Which type of glass has a higher melting point: soda-lime or borosilicate?

Borosilicate glass

How is clay formed?

When it's wet it is moulded into a shape, it is then heated until it hardens

What are composites?

Two or more different materials with contrasting properties

In composites, what is the reinforcement?

Fibres or other material that make up the bulk of a composite material

In composites, what is the role of the matrix?

The substance that binds the reinforcement together

What materials are examples of composites?

Fiberglass, carbon fibre composites, concrete and wood

What are the two types of poly(ethene)?

Low density (LD) poly(ethene) and high density (HD) poly(ethene)

What determines which type of poly(ethene) will form?

The temperature, pressure and presence of a catalyst

How is LD poly(ethene) formed?

Moderate temperatures and high pressures

How is HD poly(ethene) formed?

Lower temperatures and pressures and with a catalyst

What happens to thermosoftening plastics when they are heated?

They melt

What are some of the structural properties of thermosoftening plastics?

No covalent bonds, molecules can slide over each other

What happens to thermosetting plastics when they are heated?

They char or burn but do not melt

What are some of the structural properties of thermosetting plastics?

Strong covalent bonds between molecules

What is corrosion?

Corrosion is the destruction of materials by chemical reactions with substances in the environment

What is rusting?

A corrosion reaction in which substances react with oxygen and water

How can corrosion be prevented?

By applying a coating that acts as a barrier, such as greasing, painting or electroplating

How is aluminium protected from corrosion?

Aluminium has an oxide coating that protects the metal from further corrosion

What are alloys?

A combination of two or more elements where at least one of them is a metal

What is bronze an alloy of?

Copper + Tin

What is brass an alloy of?

Copper + Zinc

How many carats is 100 % gold?

24 carats

What elements are found in alloys with gold?

zinc, copper and silver

Why are aluminium alloys used in aircraft?

They have a low density

What are steels alloys of?

Iron with specific amounts of carbon, plus other metals

What are properities of high carbon steel?

Strong but brittle

What are properties of low carbon steel?

Soft and more easily shaped

What is stainless steel?

Steels containing chromium and nikel. They are hard and resistant to corrosion

What is the symbol equation for the haber process?

N₂ + 3H₂ ⇌ 2NH₃

Where does the nitrogen needed for the haber process come from?

The air

Where does the hydrogen needed for the haber process come from?

Reacting methane from steam to form hydrogen and carbon dioxide

State the conditions used in the haber process

Iron catalyst, high temperature (450 ᵒC) and a high pressure (200 atm)

What is the ammonia produced in the haber cycle used for?

- To make ammonium nitrate ( a very nitrogen rich fertiliser) - Can make other ammonium salts by reacting with acids - Can react it with oxygen and water to produce nitric acid

Why is 450ᵒC a compromise temperature for the Haber process?

- The forward reaction is exothermic - Increaisng the temperature favours the reverse endothermic reaction and shifts the equilibrium to the left, reducing the yield of ammonia - Too low temperatures reduce the rate of the reaction - 450 ᵒC is a compromise between the rate of the reaction and maximum yield of ammonia

Why are pressures above 200 atm not used?

- Too dangerous - Too expensive to generate the energy - Too expensive to build equipment to contain the pressure

Why is an iron catalyst used?

Increase the rate of the reaction (does not affect the yield of ammonia)

What elements are in an NPK fertiliser?

Nitrogen, phosphorous and potassium

What happens to the ammonia formed in the haber cycle?

It is produced as a gas but it cools in the condenser and liquifies. It is then removed

What happens to the unused hydrogen and nitrogen?

They are recycled

What are NPK fertilsiers?

NPK fertilisers are formulations of various salts containing appropriate percentages of the elements

Give sources of potassium for NPK fertilisers

Potassium chloride and potassium sulfate

Why can phosphate rock not be used in fertilisers?

The phosphotate salts are insoluble and so plants can't use them as nutrients

How can phosphate rock be converted into soluble phosphates?

- React with nitric acid to make phosphoric acid and calcium nitrate - React with sulfuric acid to make calcium sulfate and calcium phosphate (this mixture is known as single superphosphate) - React with phosphoric acid produces calcium phosphate (triple superphosphate)

Write a symbol equation for the reaction of ammonia with nitric acid to make ammonium nitrate

NH₃ + HNO₃ -> NH₄NO₃