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using resources Flashcards

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1
Q

Give four reasons why humans use the earth’s resources.

A

humans use the earth’s resources for:

  • warmth
  • shelter
  • food
  • transport
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2
Q

Give two cases in which resources are provided by agriculture.

A

resources provided by agriculture:

  • cotton - produced by a plant
  • trees - for timber, fuel (eg. power stations that run on biofuels, like woodchips)
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3
Q

What is meant by a synthetic object? Give an example.

A

A synthetic object is a substance made by chemical synthesis to imitate a natural product. For example, rubber naturally comes from the sap of a tree, but synthetic rubber is made from crude oil. Two thirds of the rubber today is synthetic.

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4
Q

What does it mean when natural resources are finite? Give two finite natural resources.

A

Some natural resources are finite, which means that they cannot be replaced as quickly as they are being used.

  • fossil fuels - humans use millions of kg everyday, but rate they are formed is slower
  • metals - in earth’s crust
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5
Q

What does it mean when a resource is renewable? Give an example.

A

Some resources are renewable, for example wood. This means we can replace them as quickly as they are being used.

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6
Q

What does sustainable mean?

A

Sustainable means meeting our needs without preventing future generations from meeting theirs.

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7
Q

Give three examples in which Chemistry is important in how we use resources.

A

importance of Chemistry in how we use resources:

  • to provide safe, potable water
  • artificial fertilisers allow us to grow more food with the same area of land
  • phytomining and bioleaching help to extract metals efficiently
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8
Q

What two processes can help to extract metals efficiently?

A

Phytomining and bioleaching help to extract metals efficiently

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9
Q

What is potable water?

A

Potable water is water that is safe to drink. This is essential for human life.

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10
Q

What dissolved substances are typically in water for humans?

A

For humans, water should have sufficiently low levels of dissolved salts (eg. sodium chloride) and microbes (eg. bacteria).

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11
Q

Why are potable water and pure water not the same?

A

Potable water contains small volumes of dissolved substances, but pure water contains no dissolved substances.

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12
Q

In the UK, where does most potable water come from? Why?

A

In the UK, most potable water comes from rain water as it already contains low levels of dissolved substances. This collects in the ground in aquifers, lakes, rivers and reservoirs. These reserves are plentiful in the UK.

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13
Q

Describe the process to produce potable water.

A

producing potable water:

1) choose a plentiful source of fresh water
2) pass this through filter beds to remove materials like leaves and suspended particles
3) sterilise to kill microbes (in the UK, this is done with chlorine, but other places use ozone and ultraviolet light)

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14
Q

What is desalination?

A

In many places, fresh water is scarce, so the only plentiful source is salt water, which has very high levels of dissolved minerals, so potable water is produced by desalination, which reduces the levels of dissolved minerals down to an acceptable level for human consumption.

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15
Q

What are the two ways of carrying out desalination? What is the problem with these methods?

A

methods of desalination:
- distillation
- reverse osmosis - passing it through membranes
The problem with these is that they require large amounts of energy, which makes them very expensive.

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16
Q

Why must waste water be treated?

A

A large amount of water is used for personal hygiene, flushing toilets, washing clothes and agriculture. After it has been used for these purposes, it will contain a large amount of organic molecules (eg. faeces, urine) and harmful microorganisms (eg. bacteria), so it must be treated before released into the environment again.

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17
Q

Describe the process of waste water treatment.

A

waste water treatment:

1) sewage is screened by passing through a mesh, which removes solids and pieces of grit
2) it settles in large sedimentation tanks, which produces a liquid effluent and a semi-solid sludge
3) the sludge sinks and is taken away and digested by anaerobic bacteria
- the bacteria produce biogas due to the lack of oxygen, which can be burned for electricity
- digested sludge can be used as fertilisers
4) the liquid effluent contains a large amount of organic molecules and harmful microorganisms
- air is bubbled through it so aerobic bacteria can multiply and digest the organic molecules and harmful microorganisms
5) the liquid effluent can be safely discharged back into nearby rivers

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18
Q

What must happen to water used by industry before waste water treatment?

A

A lot of water is used by industry, like in making paper and chemicals. When this water is treated, any harmful chemicals must be removed, and then they can be passed to the general sewage treatment.

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19
Q

What is the easiest way to obtain potable water? Why?

A

easiest way of obtaining potable water:

  • use ground water from aquifers
  • usually, this is safe to drink from after treated with Cl
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20
Q

Name three ways of obtaining potable water and their problems.

A

obtaining potable water:
AQUIFERS
- water here may be polluted (eg. fertilisers), so water from aquifers must be tested carefully
WASTE WATER
- directly from waste water such as sewage
- takes many purification steps
SALT WATER
- must be desalinated, which takes a lot of energy, so it is expensive

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21
Q

What are most metals like when they are found in the earth’s crust?

A

Most metals are found in the earth’s crust already reacted with other elements, such as oxygen.

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22
Q

Give one reason why copper is important.

A

Worldwide demand for metals is growing, such as copper. It is used in electronic equipment, like phones.

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23
Q

Why are metal ores good for extracting metals?

A

Metal ores contain enough metal to make it economical (cost effective) to extract the metal.

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24
Q

What is happening as a result of copper ores becoming scarce? Why is this a problem?

A

Copper ores are becoming scarce, so we need to extract copper from low-grade ores (have a small amount of copper), so it is less cost effective.

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25
Q

Describe the process of phytomining.

A

phytomining:

  • plants are grown on land with the metal compound we want
  • the plants absorb the metal compound and concentrate it in the tissue
  • the plants are then harvested and burned
  • the ash contains a relatively high concentration of metal compounds
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26
Q

Describe the process of bioleaching.

A

bioleaching:

  • bacteria is mixed with a low grade ore
  • the bacteria carries out chemical reactions, which produces a solution called leachate
  • leachate contains the metal compound we want in a higher concentration
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27
Q

How is the metal extracted from a metal compound?

A

Metals can be extracted from their metal compound through electrolysis. Copper can be extracted via displacement with scrap iron, which is much cheaper.

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28
Q

Why are phytomining and bioleaching both cost effective?

A

Phytomining and bioleaching are cost effective extraction methods from low grade ores. It is cheaper as it doesn’t involve digging, transporting or disposing od large amounts of rock, unlike mining.

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29
Q

What is a life cycle assessment?

A

A life cycle assessment attempts to put a number on the environmental impact of a product.

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30
Q

Give four factors that affect the life cycle assessment of a product.

A

factors affecting life cycle assessment:

  • impact of extracting and processing the raw materials
  • manufacturing and packaging
  • impact of use and operation during its lifetime
  • disposal of product at the end of its useful lifetime
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31
Q

Name an advantage and two disadvantages of life cycle assessments.

A

life cycle assessments:
ADVANTAGE
- the use of water, energy and the production of some waste products with reasonable accuracy
DISADVANTAGES
- cannot be certain how damaging they are to the environment, so we have to use estimates, so may be inaccurate
- can be biased, like to support advertisers

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32
Q

What is the difference in production of plastic and paper bags? What are the negatives in each?

A

production:
PLASTIC BAGS
- produced using chemicals from crude oil, which is non-renewable
- extracting crude oil can be harmful to habitats, like if there is an oil leak
PAPER BAGS
- made from wood from trees, which is renewable
- felling trees can be damaging to habitats
- making paper requires a lot of energy
BOTH
- crude oil and wood need to be chemically processed, which requires a lot of energy and releases waste products

33
Q

What is the difference in the use during the lifetime of plastic and paper bags?

A 
re-usability:
PLASTIC BAGS
- strong and reused, like in bin liners
PAPER BAGS
- not as strong and tend to tear, usually used once then thrown away
34
Q

What is the difference in the impact at the end of the lifetime of plastic and paper bags?

A

impact at end of lives:
PAPER BAGS
- take more energy to transport as they’re often heavier
BOTH
- have to be transported to recycling or landfills, which requires energy

35
Q

What is the difference in biodegradability of plastic and paper bags?

A

biodegradability:
PLASTIC BAGS
- non-biodegradable, so it is not broken down by microorganisms
- therefore, remain in the environment for a very long time, so major form of litter and fill landfills
PAPER BAGS
- paper breaks down easily, especially when wet

36
Q

Name five items produced by limited raw supplies.

A

items produced by limited raw supplies:

  • metals
  • glass
  • building materials
  • clay ceramics
  • most plastics
37
Q

Name two methods of obtaining raw materials and why they are harmful to the environment.

A

obtaining raw materials:

  • quarrying - releases lots of dust, destroying habitats
  • mining - releases harmful chemicals, destroying habitats
38
Q

Why is turning raw materials into useful products expensive and damaging?

A

It takes a lot of energy to turn raw materials into useful products, and this energy often comes from limited resources, like fossil fuels.

39
Q

Give three ways in which glass bottles can be recycled or reused.

A

Glass bottles can be reused. They can also be crushed and melted into different glass products. They can also be recycled into fleece jackets and carpets.

40
Q

Why is the reduction in use, reuse and recycling of materials beneficial?

A

The reduction in use, reuse and recycling of materials by users reduces the use of limited resources, energy sources, waste and impacts.

41
Q

How are metals recycled? What is the problem with this?

A

Metals can be recycled by melting them and reforming them into different products. A problem is that different metals need to be separated before they are recycled, but this depends on the properties of the final product.

  • for example, scrap steel can be added to iron from a blast furnace to reduce the amount of iron needed to extract from iron ore
42
Q

What is corrosion?

A

Corrosion is the destruction of materials by chemical reactions with substances in the environment. An example is rusting.

43
Q

What is rusting?

A

Rusting is the corrosion of iron and alloys of iron.

44
Q

What two things are required for rusting to occur?

A

Air and water are both required for rusting.

45
Q

Describe a way to investigate the requirements for rusting, and the observations you would see.

A

requirements for rusting investigation:
AIR AND WATER
- iron nail in distilled water, without a bung so it is open to air
- the nail will end up being covered in rust

WATER PRESENT (NO AIR)

  • iron nail in boiled distilled water (removes dissolved air) and oil layer on top (prevents air from dissolving into the water
  • no rust on the nail

AIR PRESENT (NO WATER)

  • anhydrous calcium chloride power (removes water from the air) and a rubber bung (prevents moist air from entering the tube)
  • no rust on the nail
  • therefore, air and water must both be present for rusting
46
Q

Why is corrosion a problem?

A

Corrosion is a problem as it damages materials.

47
Q

Name two ways to prevent corrosion.

A

preventing corrosion:
- a barrier between the material and the environment (such as grease, paint or electroplating (coat in a metal, for example, aluminium has an oxide coating that prevents it from further corrosion))

  • some coatings are reactive, and have a more reactive metal to provide sacrificial protection - the more reactive metal corrodes, even when scratched (for example, zinc is used to galvanise iron (coat in zinc))
48
Q

What is an alloy?

A

An alloy is a metal blended with other elements. They tend to be harder than pure metals, and most metals in everyday use are alloys.

49
Q

What is bronze? Give two properties and what is it used in.

A

Bronze is an alloy of copper and tin. It is hard and tends not to corrode, so it is used in statues.

50
Q

What is brass? Give a property and what is it used in.

A

Brass is an alloy of copper and zinc. It can be formed into shapes, so it is used in instruments and door handles.

51
Q

What is gold (in jewellery)? What is meant by carats?

A

Gold in jewellery is an alloy of silver, copper and zinc. The proportion of gold is measured in carats. For example, 24 carats is 100% gold, 12 carats is 50% gold.

52
Q

What is steel? What are the two different types and their uses?

A

Steels are alloys of iron containing specific amounts of carbon and other metals.

  • high carbon steel is extremely hard but brittle (used in cutting tools and chisels)
  • low carbon steel is softer and more easily shaped (used in car bodies)
  • contains iron, so it can rust, so stainless steel is used
53
Q

What is stainless steel?

A

Stainless steel doesn’t rust. It is an alloy of chromium and nickel. It is hard.

54
Q

What is the main property of aluminium alloys? What are they used in?

A

Aluminium alloys are of a low density, so they are used in aeroplane bodies.

55
Q

What is most of the glass today made of? Why is this ideal?

A

Most of the glass we use today is soda-lime glass. This is ideal for windows and bottles.

56
Q

How is soda-lime glass made?

A

Soda-lime glass is made by mixing sand, sodium carbonate and limestone. Then, we heat it until it melts. Then, it is moulded and we cool it.

57
Q

What is a problem with soda-lime glass?

A

One problem with soda-lime glass is that it has a low melting point, which limits its uses.

58
Q

How is borosilicate glass made?

A

Borosilicate glass is made by mixing sand and boron trioxide.

59
Q

Why, in some cases, can borosilicate glass be more useful than soda-lime glass?

A

Borosilicate glass has a higher melting point than soda-lime glass. This is useful for kitchen and lab appliances, which require heating.

60
Q

What is clay? How are they used?

A

Clay is a mineral found in the ground. When it is wet, it is shaped and heated to harden. They are used in pottery and bricks.

61
Q

What are composites?

A

Composites are made by combining two different materials. It is usually made of a reinforcement, which consists of fibres or fragments of one material, surrounded by a matrix or binder material. They have different properties based on the materials in it.

62
Q

Give two examples of composites and what they are used for.

A

composites examples:
- carbon fibre composite - contains fibres of carbon as the reinforcement and plastic resin as the matrix, it is very strong and light, so it is useful in cars and aircraft

  • reinforced concrete - steel bars surrounded by concrete, extremely strong, so used in buildings
63
Q

What two factors affect the properties of a polymer? Give an example.

A

The properties of polymers depend on the monomer and the conditions used to make the polymer.
- for example, high and low density poly(ethene) both are made of the same monomer, but the conditions they are made in affect the density

64
Q

What three things could you change to change the properties of a polymer?

A

To change the properties of a polymer, you can change the reaction temperature, pressure or the catalyst used.

65
Q

What are thermosoftening polymers? Describe why they have the properties that they have.

A

thermosoftening polymers:

  • melt when heated, so they can be reshaped and cooled
  • the intermolecular forces between the monomers break as they are heated
  • the polymer strands separate and it melts
  • if they are cooled, the intermolecular forces reform and it becomes a solid again.
66
Q

What are thermosetting polymers? Describe why they have the properties that they have.

A

thermosetting polymers:

  • don’t melt when they’re heated
  • the polymer chains are connected by strong cross links which cannot be broken by heat
67
Q

What is the Haber Process used for?

A

The Haber Process is used to manufacture ammonia, which can be used to produce nitrogen-based fertilisers for farming.

68
Q

Give the word and symbol equation for the Haber Process.

A

the haber process:
nitrogen + hydrogen (reverse reaction arrow) ammonia
N2 (g) + 3H2 (g) (reverse reaction arrow) 2NH3 (g)

69
Q

How do we get the raw materials needed for the Haber Process?

A

The raw materials needed are nitrogen and hydrogen.

  • nitrogen can be extracted from the air
  • hydrogen can be produced by reacting methane with steam
70
Q

What four conditions are required for the Haber Process?

A

needed for the haber process:

  • purified nitrogen and hydrogen
  • iron catalyst
  • 450 degrees Celsius
  • 200 atmospheric pressure
71
Q

Give three ways to increase the yield of ammonia in the Haber Process.

A

increasing yield of ammonia in the haber process:
- cool the ammonia to turn it back into a liquid, then remove it and recycle the unreacted nitrogen and hydrogen back over the catalyst
LE CHATELIER’S PRINCIPLE
- forward reaction is exothermic, so a cooler temperature will shift the equilibrium to the right side, so there is a higher yield of ammonia
- due to mol ratio, there is a higher pressure on the left side, so increasing the pressure will shift the equilibrium to the right side and increase the yield of ammonia

(catalyst has no effect on position of equilibrium)

72
Q

Name two compromises that need to be made in the Haber Process and why.

A

compromises in the haber process:
- low temperature means high yield of ammonia, but it is very slow, so 450 degrees Celsius is a compromise temperature which is a relatively fast and high yield

  • high pressures can be dangerous and they are expensive as they require energy, so 200 atmospheric pressure is a compromise
73
Q

What is the function of fertilisers?

A

Fertilisers replace the elements that have been taken up by plants.

74
Q

What are NPK fertilisers? How are they produced?

A

NPK fertilisers:

  • contain compounds of nitrogen, phosphorus and potassium
  • they are produced in large industrial facilities, where a variety of raw materials are processed together
  • they are formulations of different salts that contain the elements in specific percentages required by the plant
75
Q

What is the function of NPK fertilisers?

A

NPK fertilisers improve agricultural productivity, which help plants to grow larger and more rapidly.

76
Q

What is the main compound in NPK fertilisers? How is this compound produced?

A

The main compound in NPK fertilisers is ammonium nitrate (NH4NO3). This is made by using ammonia, which can be used to produce nitric acid, which is then reacted with more ammonia.

77
Q

What two sources can the potassium in NPK fertilisers come from?

A

potassium for NPK fertilisers sources:
- the salts potassium chloride or potassium sulfate - mined from the ground and can be used directly without further processing
- phosphate rock - must be chemically processed before being used in fertilisers, can be treated with;
> nitric acid - produces phosphoric acid and calcium nitrate; phosphoric acid can be neutralised with ammonia, produces ammonium phosphate, which can then be used in NPK
> sulfuric acid - produced a mixture of calcium phosphate and calcium sulfate, which is a single superphosphate and can be used in NPK
> phosphoric acid - makes triple superphosphate, which can be used in NPK

78
Q

Where does the nitrogen come from in NPK fertilisers? How is it produced in the lab and in the industry?

A

nitrogen in NPK fertilisers:
- ammonium nitrate - ammonium + nitric acid
IN THE LAB
- in a lab, use dilute amounts of each so it is safe
- produce crystals using a water bath and Bunsen burner, which requires a lot of heat energy
- can only produce a small amount in one go
- called the batch process
IN THE INDUSTRY
- in the industry, ammonia is used as a gas and nitric acid is concentrated, dangerous as it is very exothermic, so heat muse be safely removed and used in later stages, like some of the energy for evaporation is provided by this
- the chemical is processed by a continuous process, so thousands of kg can be produced easily

y chemistry paper two (6 decks)

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