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1
Q

State what humans use the Earth’s resources for:

x4

A
  • Warmth
  • Shelter
  • Food
  • Transport
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2
Q

What are natural resources of the Earth supplemented by?

What do natural resources provide?

A
  • They are supplemented by agriculture.

Natural resources provide:

  • Food
  • Timber
  • Clothing
  • Fuels

eg cotton and fossil fuels.

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3
Q

True or false, chemistry plays an important role in:

  • Improving agricultural and industrial processes to provide new products in sustainable development?
A

True.

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4
Q

What is meant by sustainable development?

A

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

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5
Q

Finite resource:

  • state two examples
A

A resource that runs out because they cannot be replaced as quickly as they are used

EXAMPLES
- Metal
- Fossil fuels

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6
Q

Renewable resource:

A

A resource that don’t run out because they can be replaced as quickly as they are used.

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7
Q

State an example of a natural product that has been replaced by a synthetic one:

A

Natural rubber from tree sap being replaced with synthetic rubber from crude oil.

Where does synthetic rubber come from?
Crude oil!

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8
Q

What is the difference between potable water and pure water?

A
  • Potable water is water that contains low levels of dissolved salts and low levels of microbes.
  • Pure water contains no dissolved chemicals.
  • So potable water isn’t pure as it contains dissolved chemicals.
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9
Q

Water that is safe for humans to drink must have:

A

Low levels of dissolved salts and microbes. This is called potable water.

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10
Q

What do the methods used to provide potable water in an area depend on?

x2

A
  • Water supplies in that area.
  • The local conditions of that area.
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11
Q

Describe how potable water is produced in the UK:

DO NOT MIX UP SEWAGE WATER CLEANING AND POTABLE WATER PRODUCTION!

A

In the UK rain water provides water with low levels of dissolved substances. This rain water collects in the ground and in lakes in rivers.

Potable water is produced from this rain water by:

  • Selecting an appropriate source of water eg rivers
  • Passing the water through filter beds to remove suspended particles and materials
  • Sterilising the water to kill microbes.

selection, filtration and sterilisation

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12
Q

3 ways of sterilising potable water:

A
  • Using chlorine
  • Using Ozone
  • Using ultraviolet light
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13
Q

What is fresh water?

A

Water that has low levels of dissolved minerals.

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14
Q

In countries where freshwater supplies are limited, how is potable water produced?

State a disadvantage of using these methods?

A

By desalination of salty water or sea water.

How does desalination occur?

  • By distillation

OR

  • By using processes that include membranes such as reverse osmosis.

DISADVANTAGE:

They require a lot of energy.

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15
Q

Describe the differences in the treatment of groundwater and salty water:

A

Salty - desalination by distillation or processes that include membranes.
Ground water - filtration, sterilisation

These are how we produce water, not clean it!

Cleaning - sewage and sludge
Production - potable water, desalination, ground water etc

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16
Q

True or false, urban lifestyles and industrial processes produce large amounts of waste water?

A

True.

EG showering and car washes.

What happens to this waste water before it is released back into the environment?

It is treated.

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17
Q

What may industrial waste water be require the removal of?

A

Organic matter and harmful chemicals.

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18
Q

What may sewage and agricultural waste water require the removal of?

A

Organic matter and harmful microbes.

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19
Q

Describe the process at which waste water is treated:

A
  • The sewage water is screened by being passed through a mesh in order to remove solids such as grit.
  • The sewage is left to settle in sedimentation camps and this produces liquid effluent and sludge which sinks.
  • The sludge is digested by anaerobic bacteria.
  • Air is bubbled through the liquid effluent to allow aerobic bacteria to multiply and these digest harmful microorganisms and organic molecules.
  • Now liquid effluent is safely discharged into nearby rivers or sea.
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20
Q

When sludge is digested by anaerobic bacteria what is produced, and what can this be used for?

A

The bacteria produces biogas, this can be burnt to produce electricity.

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21
Q

What can the digested sludge be used for?

A

Fertilisers for farming.

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22
Q

How is potable water easily produced with respect to:

  • Ground water
  • Waste water
  • Salt water
A

The easiest way to produce potable water is from ground water/aquifers (these can be treated using chlorine, but the water is often polluted w fertilisers from farms so these need to be tested carefully).

Water from waste water eg sewages: many purification steps so is only done in places when water is scarce.

Water fro salt water needs to be desalinated to produce potable water. Desalination requires a lot of energy so is expensive.

ORDER (easiest, to hardest).
- Ground
- Waste - many steps only where scarce
- Salt - requires alot of energy so expensive

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23
Q

Copper ores are becoming scarce so methods are being used to extract copper from low grade ores.

State two of these methods.

Also what is a low grade ore?

A
  • Phytomining
  • Bioleaching

^These methods don’t include the traditional methods of mining, digging, moving rocks and disposing large amounts of rocks.

^Low grade ores are ores that contain only a small amount of a particular metal.

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24
Q

What is a metal ore?

A

An ore that contains enough metal that makes it economical to extract the metal.

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25
Q

Describe what occurs during phytomining to extract a metal:

A
  • Plants are grown on land containing the desired metal compound.
  • The plants absorb the metal compound and concentrate it in their tissue.
  • The plants are now harvested and burned.
  • This ash now contains a relatively high concentration of the metal compound.
  • The metal compound is now processed to obtain the metal.
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26
Q

Describe what occurs during bioleaching to extract a metal.

A
  • Bacteria are mixed with a low grade ore.
  • The bacteria carry out chemical reactions to produce a solution called a leachate.
  • This leachate solution contains the desired metal compound.
  • Metal compound is now processed to obtain the metal.
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27
Q

After phytomining and bioleaching the metal is still in the metal compound, true or false?

What can we do to solve this

  • 2 methods.
A

True.

  • We can carry out displacement reactions. eg with copper we can displace the copper from its compound using iron (typically scrap iron) because iron is cheap.
  • Electrolysis.
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28
Q

Advantages of phytomining and bioleaching:

A
  • They don’t involve the digging, mining and disposing of rocks.
  • They allow us to economically extract metals from low grade ores.
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29
Q

How can copper be extracted from solutions of copper compounds?

x2

A
  • Electrolysis
  • Displacement reactions using scrap iron.
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30
Q

What are life cycle assessments (LCAs)?

A

Assessments carried out to assess the environmental impacts of products in the following stages:

  • Extracting and processing raw materials use to make the product.
  • Manufacturing and packaging of that product.
  • Use and operation of the product during its lifetime
  • Disposal of the product at the end of its life time including the transport and the distribution at each stage.

^^These stages require energy and may produce harmful waste products which affect the environment.

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31
Q

Comparative LCA for shopping bags made from plastic and paper:

A
  • Production and extraction, manufacturing, operation and disposal P.E.M.O.D

production:
- Paper bags from wood and trees (Renewable), plastic bags from chemicals in crude oil (non-renewable).

extraction:
- extraction of crude oil to make plastic bags can be harmful to habitats if there’s an oil leak, cutting down trees to make paper bags can destroy habitats.

manufacturing and processing:
- they both need to be chemically processed which requires a lot of energy and releases waste and making paper releases a lot of water.

operation:
- plastic bags = strong and reused, paper bags agents and are typically reused just once and tend to tear.

disposal:
- at the end of their lives they have to be transported either for recycling or to landfills, transporting emits GHG and plastic bags are often heavier than paper bags so requires more energy for transport.
- plastic bags are non BD so stay in the environment for a long time so are a major form of litter and also fill up land fills.

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32
Q

Issues with LCAs

A
  • Though we can measure the use of water and energy we cannot be certain of how damaging the effects of these are, so we have to make estimates or value judgements during LCAs and these aren’t always accurate.
  • They can be biased to support claims by advertisers.
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33
Q

How can we limit resources we use to:

  • Reduce the amount of use of limited resources
  • Reduce waste
  • Reduce energy use

^And the impact these have on the environment.

A
  • Recycling products we use.
  • Reusing products we use.
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34
Q

Obtaining raw materials from the Earth by processes such as quarrying and mining causes environmental impacts, true or false?

A

True.

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35
Q

Give examples of how certain materials can be recycled and reused.

A

Glass bottles:
- Simply reused
- Crushed and melted to make different glass products.

Metals:
- Can be recycled by melting and recasting.

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36
Q

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

A
  • The material being recycled.
  • The properties required of the final product.
37
Q

Give an example of a specific metal that can be recycled

A

Scrap steel can be added to iron to extract iron from iron ore.

38
Q

What is meant by corrosion?

A

The destruction of materials by chemical reactions with substances in the environment

39
Q

What are the conditions required for corrosion to occur?

A

oxygen and water

40
Q

How can we prevent corrosion?

A

Coatings (now expand)

41
Q

Give an example of corrosion

A

Rusting - RUSTING ONLY APPLIES TO IRON AND ALLOYS OF IRON SUCH AS STEEL!!!!!

42
Q

Describe how to carry out an experiment on the conditions required for rusting:

A
  • Set up three test tubes like this:
  • In one open test tube place an iron nail into distilled water (water + air)
  • In the second test tube place an iron nail into boiled distilled water covered in oil. (just water)
  • In the third test tube place an iron nail into anhydrous calcium chloride powder and cover it with a bung (just air)
  • Leave this set up for a few days and we should observe that rusting only took place on the iron nail in the test tube containing distilled water, this showed us that rusting requires air and water.
43
Q

What is coating a metal with zinc called?

A

Galvanising.

  • By coating a less reactive metal with zinc, the zinc reacts/corrodes instead of the metal and this is known as sacrificial protection.
44
Q

What is sacrificial protection?

A

When some **reactive coatings* *that contain more reactive metal are used to cover and protect a less reactive one to protect it from corrosion eg zinc coating (galvanising). w

^^In this case, the zinc is replaced every few years.

45
Q

Examples of how corrosion can be prevented:

A

Corrosion can be prevented by:

Barrier methods such as

  • Greasing
  • Painting
  • Electroplating

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

46
Q

What are alloys?

A

A metal that is blended with other elements.

^^An alloy is a mixture! They tend to be harder than pure metals.

47
Q

Why are alloys generally harder than pure metals:

A
  • They are made up of metals blended with other elements so the particles in an alloy aren’t the same size.
  • So the structure is distorted and the particles can’t slide over each other so they are hard.

^no longer arranged in regular layers

48
Q

What is bronze?

A

An alloy of copper and tin.

49
Q

What is brass?

A

An alloy of copper and zinc.

50
Q

Uses of bronze:

A
  • Bc it is hard and tends not to corrode it can be used for statues.
51
Q

Uses of brass:

A
  • Can be formed into different shapes so can be used for musical instruments and door handles.
52
Q

Gold is used in jewellery and is typically an alloy of what 3 metals?

A
  • Silver
  • Copper
  • Zinc

^Bc pure gold is too soft

53
Q

The purity of gold is measured in what?

A

Carats:

24 carat = 100% pure
18 carat = 75% gold

54
Q

What is steel an alloy of?

A

Iron containing specific amounts of the non-metal carbon and other metals.

STEEL: Iron, specific amounts of carbons, other metals.

55
Q

High carbon steel versus Low carbon steel:

Qualities and their uses.

A

High carbon steel = strong but brittle (cutting tools such as chisels)
Low carbon steel = softer and more easily shaped (car bodies)

56
Q

What is the issue with steel?

How can this be prevented?

A

Because it is an alloy of iron it can be rusted so to prevent this we have stainless steel.

57
Q

What is stainless steel an alloy of?

Advantage of stainless steel:

A

Iron, specific amounts of carbon, chromium and nickel.

It is hard but also resistant to corrosion.

58
Q

What are aluminium alloys and why are they useful?

A

Alloys of aluminium.

  • Because they are low density they are very useful for aeroplane bodies.
59
Q

How do we make soda lime glass?

What can it be used for?

Issues?

A

From sand, sodium carbonate, lime-stone.
This is heated in a furnace and melted into the shape we want.

They are ideal for:
- Windows
- Bottles

It has a relatively low melting point so this limits its uses.

60
Q

How do we make borosilicate glass?

A

From melting a mixture of sand and boron trioxide.

Has a higher melting point than sodium lime glass which allows for it to be useful for objects which require heating eg kitchenware and lab ware.

61
Q

How are clay ceramic formed?

A

Clay is a mineral found in the ground and when it is wet it can be shaped and heated in a furnace in order to harden into the shape we desire.

62
Q

What is meant by a composite and give examples of them.

A

Substances made by combining two different materials to create a product with enhanced properties.

Composites consist of reinforcement which consist of fibres of one of the materials, they make up the bulk of the composite.

This reinforcement is surrounded by a matrix/binder material (binds reinforcement together)

REMEMBER:

Composites have different properties to the materials they are made from.

EXAMPLES OF COMPOSITES:
- Carbon fibre composite!!!!
- Reinforced concrete!!!!

63
Q

What are the two categories of ceramics?

A
  • Glass ceramics
  • Clay ceramics
64
Q

What do the properties of polymers depend on?

A
  • The monomers they are produced from.
  • The conditions used to make them.
65
Q

What conditions could we change when making a polymer?

A
  • The presence of a catalyst.
  • Temperature
  • Reaction pressure
66
Q

What are thermosoftening polymers?

Advantages (in bold)

A
  • Polymers that melt when they are heated which allow us to reshape them when they are soft.
  • They eventually become solid when they are cooled down.

HOW?
- When we heat thermosoftening polymers IMF between polymer strands break, and the polymer strands separate from each other and melt.
- When we cool the melted thermosoftening polymers the IMF are reformed and the polymer returns to a solid.

67
Q

Describe the Haber process for the manufacturing of ammonia.

A

BLURT!

68
Q

Thermosetting polymers:

A

Polymers that dont melt when heated.

WHY?
Because the polymer chains are connected to each other by strong cross links which do not break when they are heated.

69
Q

How are conditions for the Haber selected to maximise the yield of ammonia produced?

A
  • We can adjust the temperature and the pressure at which the reaction is taking place to shift the position of equilibrium to the right hand side.
  • By doing this more ammonia is produced.
70
Q

What can ammonia be used for?

A

To make nitrogen based fertilisers for farming.

71
Q

What is the equation for the Haber process?

Where does nitrogen and hydrogen come from?

What are the three conditions?

A

Nitrogen + Hydrogen -> Ammonia

Conditions:
- Iron catalyst
- High temperatures
- High pressures

^This is purified nitrogen and hydrogen that undergo this reaction.

^This causes the nitrogen and hydrogen molecules to react to produce ammonia.

  • Nitrogen can be extracted from the air.
  • Hydrogen can be produced by reacting methane with steam.
72
Q

Information about the Haber process to produce ammonia:

A

It is a reversible reaction, some of the ammonia breaks back down into nitrogen and hydrogen.

How can we increase the yield of ammonia:

  • We can cool any ammonia into a liquid which is then removed.
  • Then we can recycle the unreacted nitrogen and hydrogen by passing it back over the iron catalyst.
73
Q

In the Haber process, which direction reaction is exothermic?

How can we use this to increase the yield of ammonia.

A

The forward reaction.

So to increase the yield of ammonia we can cool the reaction to shift equilibrium to the right hand side.

(Think abt it, forward reaction = exo = temp of reaction is warmer? if ygm, so if we cool the reaction equilibrium would wn restore it and move to the side that is warmer, that side is the forward reaction so ammonia yield will increase.)

74
Q

What is the issue with cooling the Haber process to increase the yield of ammonia?

What can the iron catalyst do to help?

A

A cooler temperature makes the rate of reaction slower.

So there is a trade-off between the rate of reaction and the position of equilibrium.

So 450 degrees Celsius is a compromise temperature:

We get a relatively fast rate of reaction with a relatively high yield of ammonia produced.

^The iron catalyst also increases the rate of reaction anyways.

75
Q

How can pressure be used to increase the yield of ammonia produced?

A

N2 + 3H2 -> 2NH3

More molecules on reactant side.
So if we increase the pressure, equilibrium will move to the right and the yield of ammonia will increase.

76
Q

So in summary how can we increase the yield of ammonia produced?

A
  • Cooling (forward reaction is exothermic)
  • Increasing pressure.

^Look at the graph.

77
Q

In the Haber process:

  • Low temperatures:::
A
  • Increase the yield of ammonia produced
  • Decrease the rate of the reaction.
  • Cause the reaction to require alot of energy
  • So we use the compromise 450 degrees Celsius.
78
Q

In the Haber process:

  • High pressures:
A
  • Increase the yield of ammonia
  • Are extremely dangerous and expensive
  • So we use the compromise pressure of 200 atm.
79
Q

Does the iron catalyst affect the position of equilibrium?

A

No.

Only:
- Pressure and temperature.

80
Q

What are the elements in NPK fertilisers?

A
  • Nitrogen
  • Phosphorus NOT PHOSPHATE!!!!!!!!!!!!!!
  • Potassium

^These improve agricultural productivity and help plants to grow larger and more rapidly.

81
Q

Describe how NPK fertilisers are produced.

A

BLURT

82
Q

Compare the industrial production of NPK fertilisers with their production in a lab.

A

EG The production of ammonium nitrate: (reacting ammonia with nitric acid = neutralisation reaction).

IN A SCHOOL LAB:
- We use dilute solutions of ammonia and nitric acid (it is safer to work w)
IN INDUSTRY:
- Ammonia is used as gas and nitric acid is concentrated.
- This reaction is more dangerous as it is exothermic so the heat is removed and used in later stages.

IN A SCHOOL LAB:
- We produce crystals using a water bath and a Bunsen burner, this requires a lot of energy.
IN INDUSTRY:
- Some of the energy for evaporation is provided by the heat energy given of by the exothermic reaction.

IN A SCHOOL LAB:
- We can only produce a small amount of ammonium nitrate (batch process)
IN INDUSTRY:
- Chemicals are produced in a continuous process so a lot is produced at once easily.

LAB
Small batch quantities
Dilute solutions of gases and liquids
Evaporation to form crystals has energy from bunsen burner and water bath

INDUSTRY
Continous - easily make a large amount at a time
Concentrated solutions of gases and liquids
Evaporation to form crystals is supplied by energy release from exothermic reactions.

83
Q

True or false, NPK fertilisers are formulations of different salts?

A

True.

These salts contain the appropriate percentages of the N, P and K elements needed by plants.

84
Q

Compounds containing Nitrogen in NPK fertilisers:

A

Ammonium Nitrate. (NH4NO3)

85
Q

How is ammonium nitrate produced?

A
  • Ammonia produced by the Haber process can be used to produce nitric acid.
  • The nitric acid is reacted with MORE ammonia to produce ammonium nitrate.
86
Q

Where does the potassium in NPK fertilisers come from?

How are these extracted, where do they come from?

A

The salts:

  • Potassium chloride OR Potassium sulfate.

^These compounds are mined from the ground and can be used directly without any further processing.

87
Q

Where does the Phosphate in NPK fertilisers come from?

A
  • Phosphate rock is mined from the ground.
  • Phosphate rock needs to be processed before being used in fertilisers.

HOW?
- Nitric acid
- Sulfuric acid
- Phosphoric acid

88
Q

What three acids are used to treat phosphate rock?

HOW?

A
  • Nitric acid
  • Sulfuric acid
  • Phosphoric acid

HOW?

NITRIC ACID
- Treating phosphate rock with nitric acid will produce phosphoric acid and calcium nitrate.
- Phosphoric acid contains phosphorus, but we can’t add this directly to plants, so we neutralise it with ammonia.
- This produces ammonium phosphate which can be used in NPK fertilisers.

SULFURIC ACID
- Treating phosphate rock with sulfuric acid will produce calcium sulfate and calcium phosphate.
- This mixture is called single superphosphate which can be used in NPK fertilisers.

PHOSPHORIC ACID
- Treating phosphate rock with phosphoric acid produces triple superphosphate.
- This can be used in NPK fertilisers.

GCSE Chemistry (13 decks)

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