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AQA Chemistry GCSE > RESOURCESSSS > Flashcards

RESOURCESSSS Flashcards

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1
Q

what do humans use the earths resources for

A

warmth, shelter, food, transport

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2
Q

how are most of earths resources made

A

agriculture

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3
Q

what are trees used for

A

timber and fuel

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4
Q

how is synthetic rubber produced

A

using crude oil

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5
Q

where does natural rubber come from

A

the sap of a tree

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6
Q

what does it mean when a resource is finite

A

they cant be replaced as quickly as theyre being used, theyll eventually run out

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7
Q

examples of finite resources

A
  • metal
  • fossil fuels
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8
Q

examples of renewable resources

A

wood

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9
Q

what does renewable mean

A

we can replace these resources as quickly as we use them, so theyll never run out

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10
Q

what does it mean when human activities are SUSTAINABLE

A
  • we can meet our needs without preventing future generations to meet theirs
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11
Q

examples of how chemistry plays an important role in how we use resources

A
  • Artificial fertilisers allow us to grow more food with the land available
  • provides us with water safe to drink
  • processes such as phytomining and bioleching help us extract metals more efficiently
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12
Q

what does water have to contain to make it safe enough for humans to drink

A
  • low levels of dissolved salts such as sodium chloride
  • low levels of microbes such as bacteria
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13
Q

what is potable water

A

water that is safe to drink

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14
Q

what is the difference between pure water and potable water

A

pure water contains no dissolved substances at all and has a ph of 7, whilst potable water contains dissolved substances, but in quite small amounts

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15
Q

where does most potable water come from in the UK and why

A

rainwater, it contains low levels of dissolved substances
- rain collects in the ground in aquifers and in lakes, rivers and reservoirs and all of these are good sources of fresh water

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16
Q

how to produce potable water

A
  1. First choose a good source of fresh water, eg a river
  2. Pass the water through filter beds to remove all leaves and suspended particles
  3. Sterilise the water with chlorine, UV light or ozone to kill microbes
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17
Q

how is potable water produced in countries where the water is either to salty to drink

A

desalination

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18
Q

what does desalination do

A

it reduces the levels of dissolved minerals down to an acceptable level for potable water

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19
Q

how to carry out desalination

A

using distillation
- pass the water through membranes, reverse osmosis

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20
Q

disadvantages of desalination

A

require very large amounts of energy which makes them expensive

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21
Q

examples of what humans use water for

A
  • hygiene like baths and showers
  • flushing toilets
  • washing clothes
  • agriculture
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22
Q

what does waste water contain

A
  • a very large amount of organic molecules (eg from urine and faeces)
  • harmful microorganisms such as bacteria
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23
Q

How is waste water treated step by step

A
  1. The sewage us screened by passing through a mesh, this removes solids and pieces of grit
  2. the sewage settles in large sedimentation tanks
  3. The sludge is taken away and digested by anaerobic bacteria
    4.air is bubbled through the liquid effluent
  4. After this stage, the liquid effluent can be safely discharged into nearby rivers or seas
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24
Q

why is the sewage passed through a mesh

A

removes solids and grit from the water

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25
Q

why does the sewage settle in large sedimentation tanks

A

this produces a liquid effluent and a semi solid sludge which sinks

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26
Q

why is the bacteria used in waste water treatment useful

A

in the absence of oxygen, these bacteria can produce biogas which can be burned for electricity

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27
Q

what can digested sludge be used for

A

fertilisers and farming

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28
Q

why is air bubbled through the liquid effluent

A

The liquid effluent contains large amounts of organic molecules and harmful microorganisms, so bubbling air through it allows aerobic bacteria to multiply

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29
Q

why are the aerobic bacteria useful

A

in the presence of oxygen, the aerobic bacteria digest the organic molecules and harmful microorganisms

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30
Q

what is the easiest way to produce potable water

A

using ground water from aquifiers, this is safe to drink once it has been treated with chlorine
- however, they can be polluted with fertilisers from farms

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31
Q

where are most metals found

A

in the Earths crust, already reacted with other elements

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32
Q

uses of copper

A
  • used in electronic equipment such as phones
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33
Q

what does a metal ore contain

A

it contains enough metal to make it economical to extract the metal

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34
Q

what foes economical mean

A

cost effective

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35
Q

problems with extracting copper from its ore

A

they are becoming scarce(running out)

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36
Q

what are low grade ores

A

ores that contain a small amount if the metal, meaning they are harder to extract economically

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37
Q

how does phytomining work

A
  1. Plants are grown on the land containing the metal compound we want
  2. The plants absorb the metal compound and they concentrate it in their tissue
  3. The plants are then harvested and burned
  4. The ash contains a relatively high concentration of the metal compound
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38
Q

how does bioleaching work

A
  1. Bacteria are mixed with the low grade ore
  2. The bacteria carry out chemical reactions and they produce a solution called a leachate
  3. The leachate contains the metal compound we want
    4.
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39
Q

How to extract a metal from its COMPOUND (not ore)

A
  • if it is a low reactivity metal, we can use a displacement reaction
  • using electrolysis
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40
Q

why are bioleaching and phytotyming useful

A
  • they allow us to economically extract metals from low grade ores, which is important as the Earth’s resources of metal ores are limited
  • ## these methods dont involve digging, transporting, and disposal of large amount of rock like traditional mining
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41
Q

carry out a life cycle assessment on a plastic bag vs paper bag

A

EXTRACTION/ RAW MATERIALS - produced using chemicals from crude oil(non renewable)
- produced from wood from trees(renewable)
- both need to be chemically processed, which requires a large amount of energy and releases waste products

  • plastic bags are strong, can be reused
  • paper bags weak and can rip easily
  • both plastic and paper bags have to be transported
    -paper bags heavier than plastic, takes more energy to transport
  • plastic is non biodegradable, so major form of litter, fill up landfills
  • paper breaks down quickly when whet
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42
Q

what are some issues with life cycle assesments

A
  • we cannot be certain of how damaging some waste products are to the environment
  • this means in some cases we have to make estimates or value judgements which may not always be accurate
  • LCAS can be biased eg to support claims by advertisers
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43
Q

what are the stages of LCAs

A
  1. Raw materials and extraction
  2. Manufacture
  3. Transportation
  4. Use
  5. Disposal
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44
Q

examples of materials that humans produce

A

plastic
glass
metal
clay ceramics

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45
Q

how are raw materials often obtained

A

by quarrying and mining
- takes a lot of energy to turn these raw materials into useful products

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46
Q

disadvantages of quarrying

A

produces large amounts of dust
destroys habitats

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47
Q

disadvantages of mining

A

can release harmful chemicals into the environment

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48
Q

why is recycling and reusing important

A

they help save limited resources and energy
- will reduce the amount of waste that we produce, will have a less harmful effect on the environment

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49
Q

how can glass bottles be reused

A

they can be crushed and melted to make different glass products

50
Q

how can metals be recycled

A

be melting and recasting or reforming into different products

51
Q

problems with recycling metals

A
  • they usually need to he separated before being recycled, but this depends on the properties of the final product
52
Q

how to reduce the amount of iron that we need to extract from iron ore

A
  • some scrap steel can he added to iron from a blast furnace
  • this reduces the amount of iron that we need to extract from iron ore
53
Q

what is corrosion

A

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

54
Q

examples of corrosion

A

rusting

55
Q

what materials does rusting occur on

A

iron and alloys of iron

56
Q

how to investigate the conditions required for rusting

A
  1. Fill three test tubes and put an iron nail in each, one filled with with distilled water, one filled with boiled distilled water and covered in oil, and the last filled with ANHYDROUS calcium chloride powder with a rubber bung on the test tube
    - leave these for several days and look for changes
57
Q

why is the water covered in oil in the corrosion experiment

A

to prevent any air in the test tube from dissolving in the water

58
Q

what does anhydrous calcium chloride do

A

removes any water from the air in the test tube

59
Q

what dos a rubber bung do

A

prevents any moist air from entering

60
Q

what will the results of the corrosion experiment be

A
  • in the first test tube, the iron is covered in rust
  • in the other test tubes, there is no rust
  • this tells us rusting requires both air and oxygen
61
Q

how to stop corrosion

A
  • grease or paint the material
  • coat the material with metal (electroplating)
  • galvanising (coating metal with zinc)
62
Q

why does galvanising prevent corrosion

A
  • the layer of zinc acts as a barrier against air and water. this prevents the iron from corroding
  • if the zinc gets scratched, it still prevents corrosion since zinc is more reactive than iron, but the zinc corrodes rather than the iron
63
Q

what is sacrificial protection

A

using a more reactive metal layer on top of a less reactive one

64
Q

what is an alloy

A

a mixture which contains a metal blended with other elements

65
Q

how are alloys made

A

by melting our metal, mixing in other elements, and then allowing the alloy to cool

66
Q

why are alloys harder than pure metals

A
  • since the atoms in a metal form layers, if we hammer the pure metal, its layers will slide over each other
  • the atoms in an alloy are different sizes and this disrupts the layers and stops them from sliding
67
Q

features of bronze

A
  • it is an alloy of copper and tin
  • used for statues as it is extremely hard and tends not to corrode
68
Q

features of brass

A
  • is an alloy of copper and zinc
  • harder than pure copper, but can be formed into different shapes
  • can be used for musical instruments or door handles
69
Q

how is gold made harder

A

by being alloyed with silver copper and zinc

70
Q

what is 24 carat

A

100% pure gold

71
Q

what is 18 carat

A

75% pure gold

72
Q

features of steel

A
  • steels are alloys of iron, containing specific amounts of carbon
73
Q

features of high carbon steel

A
  • extremely hard
  • brittle
  • tends to break if we hit it with a hammer
  • used to make cutting tools such as chisels
74
Q

features of low carbon steel

A
  • softer than HCS
  • more easily shaped
  • used to make car bodies
75
Q

why can steel rust

A

because its an alloy of IRON

76
Q

how to prevent the rusting of steel

A

use stainless steels, which contain chromium and nickel, which are resistant to corrosion

77
Q

features of aluminium alloys

A
  • they are low density
  • used in aeroplane bodies
78
Q

what is the most used type of glass

A

soda lime glass

79
Q

uses of soda lime glass and how to make it

A
  • used in windows and bottles
  • to make soda lime glass, mix sand, sodium carbonate and limestone
  • heat this into a furnace until it melts
  • when it cools, it solidifies into any shape we want
80
Q

features of borosilicate glass

A
  • higher melting point than soda lime
  • this makes the glass more useful for objects which require heating such as kitchenware and labware
81
Q

how is borosilicate glass made

A
  • melting sand and boron trioxide
82
Q

how are clay ceramics made

A
  • by shaping wet clay then heating them in a furnace
83
Q

what is clay

A

a mineral we find in the ground

84
Q

what are composites

A

a combination of two or more materials to improve properties

85
Q

how are composites made

A

from two materials, a matrix and a binder surrounding and binding together fibres or fragments of the other material, which is called reinforcement

86
Q

examples of composite materials

A
  • carbon fibre composite (carbon as the reinforcement material and plastic resin as the matrix) - strong an light so used in cars or aircraft parts
  • reinforced concrete - strong and used to make buildigs
87
Q

how is a polymer formed

A

by joining together a large number of monomers

88
Q

what do the properties of polymers depend on

A
  • the monomer
  • the conditions used to make the polymer
89
Q

features of low density polyethene

A
  • soft
90
Q

properties of high density polyethene

A
  • harder
91
Q

how could we change the properties of a polymer

A
  • change temperature
  • change pressure
  • change reaction catalyst
92
Q

properties of thermosoftening polymers

A
  • they melt when heated
  • we can reshape them while they are soft
  • they go back to a solid when we cool them down
93
Q

what happens if we heat then cool a thermosoftening polymer (structure wise)

A
  1. Thermosoftening polymers are held together by intermolecular forces
  • If we heat the polymer, the intermolecular forces break, now the polymer strands can separate from each other and the polymer melts
    2. If we cool the melted polymer, we reform the intermolecular forces, and the polymer goes back to solid
94
Q

properties of thermoSETTING polymers

A
  • they do not melt when heated
  • polymers are connected to each other by strong crosslinks
95
Q

why dont thermosetting polymers heat when melted

A
  • the string crosslinks are not broken by heat
96
Q

uses of ammonia

A

nitrogen based fertilisers

97
Q

how is ammonia produced

A

using the Haber process, purified nitrogen and hydrogen are passed over an iron catalyst at around 450 degrees celsius and 200 atmospheres pressure, and this causes some of the hydrogen and nitrogen to react to form ammonia

  • as its a reversible reaction, some of the ammonia breaks back down into nitrogen and hydrogen
98
Q

equation for the Haber process

A

N2+3H2 —> 2NH3

99
Q

how can nitrogen be extracted

A

from the air

100
Q

how is hydrogen produced for the Haber process

A

by reacting methane with steam

101
Q

how to increase the yield of ammonia

A
  • cool the ammonia to turn it into a liquid which is removed
  • recycle the unreacted nitrogen and hydrogen back over the catalyst
102
Q

in the Haber process, which reaction is EXOTHERMIC?

A

the forward reaction, meaning a relatively cool temperature will shift the equilibrium to the right hand side

103
Q

why can the rate of reaction and equilibrium never be constant in the haver process

A
  • equilibrium will shift to the right if temperature is too low for example
  • a cooler tenperature will make the reaction slow
  • so there is a trade off between the rate of reaction and equilibrium
104
Q

why do we use a temperature of 450 degrees in the Haber process

A
  • its a compromise temperature as we get a relatively fast rate and a relatively high yield of ammonia
  • high temperatures require more energy and this costs more
105
Q

why can we not go higher than 200 atmosphere pressure with the Haber process

A
  • very high pressures are expensive and dangerous
106
Q

why are fertilisers critical for modern farming

A

they replace the elements which have been taken up by plants

107
Q

what do NPK fertilisers contain why are these useful

A
  • nitrogen
  • phosphorus
  • potassium
  • compounds containing these elements improve agricultural productivity and they help plants grow larger and more rapidly
108
Q

what are NPK fertilisers

A

formulations of various salts containing appropriate percentages of the elements

109
Q

what is the main compound of nitrogen in NPK fertilisers and how is it made

A

ammonium nitrate(NH4NO3)
- made by using ammonia made through the Haber process, we can use this ammonia to produce nitric acid
- we then react the nitric acid with more ammonia to make ammonium nitrate

110
Q

how is the potassium in NPK fertilisers produced

A
  • comes from the salts potassium chloride and potassium sulfate
  • both these compounds are mined from the ground and can be used directly without any further processing
111
Q

how is the phosphorus in NPK fertilisers produced (nitric acid)

A
  • treating phosphate rock with nitric acid produces phosphoric acid and calcium nitrate
  • phosphoric acid contains phosphorus, but we cannot add this directly to plants, so we neutralise it with ammonia
  • this produces ammonium phosphate which can be used in NPK fertilisers
112
Q

how is the phosphate in NPK fertilisers produced (sulfuric acid)

A
  • if we treat phosphate rock with sulfuric acid, we make a mixture of calcium phosphate and calcium sulfate
  • this mixture is called a single superphosphate and this can be used in NPK fertilisers
113
Q

what happens if we treat phosphate rock with phosphoric acid

A

we make a triple superphosphate and these can be found in NPK fertlisers

114
Q

compare the industrial production of fertilisers with the laboratory preparations

A
  • for example, ammonium nitrate is made by mixing ammonia with nitric acid and this is a neutralisation reaction
  • in the school lab, we would use dilute solutions of ammonia and nitric acid to make them safe to work with
  • in industry, the ammonia is used as gas and the nitric acid is concentrated. this is much more dangerous as the reaction is very exothermic, meaning the heat had to be safely removed and used for later stages
  • in the school lab, we produce crystals by using a water bath and bunsen burner which requires a lot of heat energy
  • in the industry, some of the energy for evaporation is provided by the exothermic reaction from earlier
  • in the school lab, we can only produce a small amount of ammonium nitrate in one go, this is called a batch process
  • in industry, the chemical is produced by a continuous process, meaning that thousands of kilograms can be produced easily
115
Q

what does a life cycle assessment attempt to do

A

put a number in the environmental impact of a product

116
Q

what does boiling the distilled water do

A

removes any dissolved air

117
Q

how does aluminium protect itself from corrosion

A

the surface of aluminium naturally reacts with oxygen in the air to form a. thin layer of aluminium oxide which protects the metal beneath from further corrosion

118
Q

disadvantages of soda lime glass

A

low boiling point limits its uses

119
Q

examples of clay ceramics

A

pottery
bricks

120
Q

how are clay ceramics made

A
  • when it’s wet, clay can be shaped
  • it’s then heated in a furnace to harden

AQA Chemistry GCSE (27 decks)

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