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chemistry > Water and using our resources > Flashcards

Water and using our resources Flashcards

1
Q

How do humans use resources

A

To provide warmth, shelter food and transport

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2
Q

Where do our resources come from

A

The earths crust, oceans or atmosphere

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3
Q

How do we produce our resources

A

By agriculture

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4
Q

What does modern agriculture help us so

A

It helps us grow enough resources to meet the demands of the world

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5
Q

What are trees used for

A

Timber or fuel

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6
Q

How does agriculture help us

A

It helps us use the earths resources more efficiently

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7
Q

What have we done to prevent the use of the earths resources

A

We have replaced natural resources with synthetic alternatives

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8
Q

Example of an synthetic alternative

A
  • rubber, natural rubber comes from the sap from trees whilst synthetic rubber comes from crude oil, 2/3 of the world use synthetic rubber
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9
Q

What are finite resources

A

Resources that cannot be replaced as quickly as they are being used

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10
Q

Examples of finite resources

A
  • fossil fuels
  • metals
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11
Q

What are renewable resources

A

Resources that can be replaced at the same rate they are used

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12
Q

What is sustainable development

A

Development that meets the needs of the current generation without preventing future generations from meeting theirs

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13
Q

How does chemistry play an important role in how we use resources

A
  • artificial fertilizers allow is to grow more food with the land available
  • it provides water that is safe to drink
  • processes such as phytomining and bioleaching allow us to extract metals more efficiently
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14
Q

How has the availability of natural resources changed over the past years

A
  • in the past natural resources were sufficient to provide the human population with food, timber, clothing and fuel’s however as the population increased humans had to rely on agriculture to replace and supplement each resource
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15
Q

How to analyse a sample of water for purity REQUIRED PRACTICAL

A

1) check the pH of water by placing a small amount of water into a piece of universal indicator paper
2) the universal indicator is green if the pH is 7 and if the pH is not 7 then the water sample contains dissolved acid or alkali and therefore not pure
3) if the pH is 7 it doesn’t mean that the water is pure so we would have test for dissolved solids
4) to do this we would first use a balance to weigh an empty evaporating basin and record the mass
5) we would fill the evaporation basin with the water sample and place it on a tripod and gauze
6) we then would use a Bunsen burner to gently heat the water until it’s fully evaporated
7) after this we would allow the evaporating basin to cool and then weigh it again
8) if the water contained any dissolved solids the mass of the empty basin would’ve increased so it would have not been pure, if the mass of the evaporating basin did not increase then the water did not contain any dissolved solids and could be pure

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16
Q

Why would the mass of the evaporating basin increase in the How to analyse a sample of water for purity REQUIRED PRACTICAL

A

Since the water would contain dissolved solids so the water would’ve evaporated but the dissolved solids would formed crystals on the surface of the evaporating basin basin

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17
Q

Why would the water might not be pure even though the evaporating basin did not increase in mass in the How to analyse a sample of water for purity REQUIRED PRACTICAL

A

As it may still contain dissolved gas so still might not be pure

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18
Q

How to purify seawater by distillation REQUIRED

A

1) add a few anti bumping granules to the solution and gently boil the salt solution
2) at this point the water will evaporate into water vapour
3) the water vapour travels along the delivery tube into test tube
4) when the water vapour enters the cold test tube it condenses into distilled water

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19
Q

Characteristics of pure water

A
  • contains a pH of 7
  • does not contain dissolved substances
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20
Q

Characteristics if potable water

A
  • does not have a pH of 7
  • contains dissolved substances
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21
Q

What does drinking water have to contain

A

Low levels of dissolved salts and microorganisms to be safe for humans

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22
Q

What is potable water

A

Water that is safe to drink and is good quality

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23
Q

How do we obtain potable water in the UK

A

1) fresh water from a suitable source such as aquifer, lakes, rivers and reservoirs is collected
2) the water is them passed through filter beds to remove leaves and solid particles
3) the water is then sterilised to kill microbes by using chlorine (which is used in the Uk) ozone or ultraviolet light
4) fluoride is then added to prevent tooth decay

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24
Q

Why do we use fresh water as potable water

A

As it contains low dissolved minerals

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25
Q

What do we do if our fresh water supplies are limited

A

We can desalinate sea water to produce potable water

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26
Q

What does desalination do

A

It reduces the levels of dissolved minerals down to an accepted level for potable water

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27
Q

How do we carry out desalination

A
  • by distillation
  • by reverse osmosis
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28
Q

Disadvantages of desalination

A

Both processes of desalination uses large amounts of energy making it very expensive

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29
Q

Advantages of desalination

A

It reduces the levels of dissolve minerals to an accepted level for potable water

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30
Q

What happens during desalination

A
  • the water is boiled to produce steam
  • the steam is condensed to produce pure liquid water
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31
Q

What is a large amount of potable water used for

A
  • Personal hygiene
  • flushing toilets
  • washing clothes
  • agriculture
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32
Q

What produces waste water

A
  • homes
  • agriculture
  • industrial
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33
Q

What dies waste contains

A
  • large amounts organic molecules
  • harmful microorganisms
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34
Q

How is waste water treated

A

1) the sewage is screened by passing through a mesh, this removes solids and pieces of grit
2) the sewage is then left to settle in large sediment tanks, this produces a liquid effluent and a semi solid sludge which sinks, the sludge is taken away and digested by anaerobic bacteria
3) in the absence of oxygen the bacteria produces biogas which can be burned for electricity
4) the digested sludge can be used as fertilisers for farming
5) the liquid effluent contains large amounts of organic molecules and harmful organism which both need to be reduced before returning the water to the environment
6) air is bubbled through the liquid effluent which allows aerobic bacteria to multiply
7) in the presence of oxygen the aerobic bacteria digest the organic molecules and harmful microorganisms, and after this stage the effluent can be safely discharged into rivers

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35
Q

Ways to produce potable water

A
  • ground water form aquifers
  • waste water
  • desalination
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36
Q

Pros of making potable water from aquifers

A
  • safe to drink once it has been treated with chlorine
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37
Q

Cons of making potable water from aquifers

A
  • can be polluted with fertilisers from farms so the water from aquifers need to be tested
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38
Q

Cons of making potable water from waste water

A
  • takes to many purification steps so is only done in places where water is scarce
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39
Q

Cons of making potable water from desalination

A
  • require a lot of energy and is expensive
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40
Q

What is copper used for

A
  • electronic devices
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41
Q

Cons of copper ores

A
  • copper ores are becoming scarce, so we are going to have to extract copper from low grade ores and low grade ores only contain a small amount of copper so it would be harder to extract the copper economically from the ores
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42
Q

Why is copper useful

A
  • it’s a good conductor or electricity and heat
  • it’s easily bent and hard enough to make pipes and tanks
  • does not react with water so it lasts a long time
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43
Q

Ways low grade copper is extracted

A
  • phytomining
  • bio leaching
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44
Q

How is copper extracted from phytomining

A
  • the plants are grown on land contains the metal compound we want
  • the plants then absorb the metal compound and concentrate it in their tissue
  • the plants are then harvested a burnt and at the end the ash contains a high concentration of the metal compound
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45
Q

How is copper extracted from bio leaching

A
  • bacteria are mixed with a low grade ore, the bacteria carry out chemical reactions and produce a solution called leachate
  • the leachate contains the metal compound we want
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46
Q

Ways to extract the metal compound of copper from the low grade ore

A
  • electrolysis
  • displacement of scrap iron ( as its more reactive)
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47
Q

Adv of phtomining and bio leaching

A
  • both allow us to economically extract metals from low grade ores
  • don’t involve digging, transporting and disposing if large amounts of rock unlike traditional mining
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48
Q

What is a life cycle assessment

A

Is used to access the environmental impacts a product has over its whole lifetime

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49
Q

What does a life cycle assessment do

A

Provides a way of comparing several alternative products to see which once causes the least damage to the environment

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50
Q

How to scientist carry out life cycle assessments

A

By measuring the impact of
- extracting the raw material
- processing the raw material
- manufacturing the product
- how the product is used
- how the product is transported
- the environmental impact of the product during its lifetime
- how the product is disposed at the end of its life

51
Q

Life cycle assessment for a shopping bag made from plastic

A
  • plastic bags are produced using chemicals from crude oil , crude oil is non renewable resource
  • extracting crude oil is harmful to habitats
  • need to be chemically processed which requires a large amount of energy and releases waste products
  • plastic bags are strong and reusable
  • at the end of its life it’s transported either for recycling or to landfills
  • plastic bags are light so don’t require as much energy to transport
  • plastic bags are non biodegradable, so they remain in the environment for a long time, resulting it to be a major form of litter and leading them to fill up landfills
52
Q

Life cycle assessment for a shopping bag made from paper

A
  • paper bags are made from wood from trees, trees are renewable as we can plant more
  • felling trees is destructive to habitats
  • need to be chemically processed, which requires large amounts of energy and releases waste products, making paper also requires huge amounts of water
  • paper bags are weak as they tend to tear and are only used once before being thrown away
  • at the end of its life it’s transported either for recycling or to landfills
  • paper bags are heavy so require more energy to transport
  • they are biodegradable so don’t remain in the environment
53
Q

Pros of life cycle assessment

A
  • can measure the use of water and energy
  • can measure the production of some waste products
54
Q

Cons of life cycle assessments

A
  • cannot be certain how damaging they are to the environment, so we have to make estimates it value judgments which may not be accurate
  • can be biased
55
Q

How are raw materials obtained

A
  • quarrying, this produces large amounts of dusts and destroys habitats
  • mining, releases toxic chemicals
56
Q

why is it important to reduce our needs for raw material

A
  • it takes a lot of energy to extract raw materials
  • raw materials are becoming scarce
  • it will help save limited resources and energy
  • it will reduce the amount of waste we produce and have a less harmful effect on the environment
57
Q

how do we recycle metals

A
  • we melt them and then recast them into different products
58
Q

cons of recycling metals

A
  • different metals have to be separated before being recycled
59
Q

examples of materials that can be reused

A
  • water glass can be crushed, melted and reused
  • some waste plastic can be recycled to make fleece material
  • metals can be recycled by melting them down and then making them into new objects
60
Q

what is corrosion

A

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

61
Q

example of corrosion

A

rusting

62
Q

where does rusting occur

A

ONLY in iron or other allloys of iron

63
Q

experiment for conditions required for rusting

A

1) place 3 test tubes- in test tube 1 place an iron nail in distilled water and leave the test tube open to air (this test tube has water and air)
2) in test tube 2 place an iron nail in boiled distilled water, boiling the water removes any dissolved air the water is then covered with oil to prevent any air in the test tube from dissolving in the water (this test tube has water but no air)
3) in test tube 3 place the iron nail in anhydrous calcium chloride powder, this removes any water from the air in the test tube, a rubber dung is also placed on top of the test tube to prevent any moist air from entering (this test tube has no water but air )
4) leave the test tubes for several days
5) in test tube 1 the iron nail should be covered with rust, test tube 2 and 3 there is no rust and this tells us that rust requires water and air

64
Q

cons of corrosion

A

damages materials

65
Q

how to prevent corrosion

A
  • by using a barrier between the environment and the material we want to protect by using grease or paint or by electroplating (coating it with a metal)
66
Q

how is aluminium protected from corrosion

A

the surface of the aluminium react with the oxygen to produce a thin layer of aluminium oxide, which protects it from further corrosion

67
Q

what is galvanising

A

coating a metal with zinc

68
Q

how does galvanising help with corrosion

A

the layer of zinc acts as a barrier against air and water, this prevents the metal from corroding
- if the zinc is more reactive than the metal it will still protect it from corrosion even when its scratched as the zinc will corrode instead of the metal (sacrificial protection)

69
Q

what is sacrificial protection

A

when a more reactive metal is placed in contact with a less reactive metal

70
Q

what is an alloy

A

contains a metal blended with other elements

71
Q

alloys of copper

A
  • bronze
  • brass
72
Q

why do we mix gold with other metals

A
  • to make it harder as pure gold is soft
73
Q

how many carats in 100% pure gold (bruno mars)

A

24 carats

74
Q

what is steel

A

alloy of iron containing specific amount of carbon

75
Q

characteristics of high carbon steal

A
  • extremely hard
  • brittle
  • breaks if hit with a hammer
  • used to make cutting tools
76
Q

characteristics of low carbon steel

A
  • softer
  • more easily shaped
  • used to make car bodies
77
Q

cons of steel

A
  • made of iron so can rust
78
Q

how do we prevent steel from rusting

A
  • by using stainless steel which contains iron carbon, chromium and nickel
  • stainless steel is hard but resistant to corrosion
79
Q

characteristics of aluminium alloys

A
  • low density
80
Q

what are ceramics

A

they are made from soft substances, which when heated become hard and brittle.

81
Q

how do we make soda lime glass

A

by mixing together sand, sodium carbonate and limestone we then heat this mix in a furnace until it melts and when it cools it solidifies into any shape we want

82
Q

cons of soda lime glass

A
  • has a low boiling point which limits its uses
83
Q

pros of borosilicate glass

A
  • has a high boiling point which makes it useful for objects that require heating such as kitchen
84
Q

what is borosilicate glass

A
  • made by melting a mixture of sand and boron trioxide
85
Q

examples of ceramics

A
  • glass ceramics (borosilicate glass and soda lime glass)
  • clay ceramics
86
Q

what is clay

A

a mineral found underground

87
Q

how are clay objects made

A
  • when clay is wet, it can be shaped and then is heated in the furnace to be harden
88
Q

what are composite materials

A
  • consists of two materials with different properties
89
Q

uses of soda lime glass

A
  • drinking bottles
  • windows
  • bottles
90
Q

example of composite materials

A
  • reinforcement - this consists of fibres of fragments of one material, the reinforcement is surrounded by a matrix material
  • carbon fibre composite
  • reinforcement concrete
91
Q

pros of carbon fibre composites

A
  • very stong and light, making it extremely useful
92
Q

pros of reinforced concrete

A
  • really strong and is used to make building
93
Q

what is reinforced concrete made out of

A
  • steel bars surrounded by concrete
94
Q

what is carbon fibre composite made from

A
  • fibres of carbon and the matrix is plastic resin
95
Q

how do we change the properties of a polymer

A
  • by changing the reaction temperature, pressure or the catalyst
96
Q

what happens to thermosoftening polymers when we heat them

A
  • they melt and once they melt we can reshape them whilst there soft and they go back to a solid once cooled
97
Q

why do thermosoftening polymers melt once we heat them and cool them

A
  • as when we heat the polymer the intermolecular forces break so the polymer strands separate from each other and the polymers melt
  • when we cool the melted polymer we reform the intermolecular forces and the polymer goes back to a solid
98
Q

what happens when you heat a thermosetting polymer

A
  • it does not melt
99
Q

why don’t thermosetting polymers melt

A

-in thermosetting polymers the polymer strands are connect by strong links, the strong links are not broken by heat which is why thermosetting polymers do not melt when heated

100
Q

uses of ammonia

A
  • making nitrogen based fertilisers for farming
101
Q

how is ammonia made

A

the haber process

102
Q

word equation for haber process

A

nitrogen + hydrogen ——> ammonia
<——-

103
Q

symbol equation for haber process

A

N2 + 3H2 ——–> 2NH3
<———

104
Q

source for raw materials used in the haber process

A
  • nitrogen can be extracted from the air
  • hydrogen is produced by reacting methane with steam
105
Q

steps of haber process

A

1) purified nitrogen and hydrogen are passed over an iron catalyst at around 450 degrees and 200 atmospheres pressure
2) this causes some of the nitrogen and hydrogen atoms to react forming ammonia
3) this is a reversible reaction as some of the ammonia can be broken down into nitrogen and hydrogen

105
Q

steps of haber process

A

1) purified nitrogen and hydrogen are passed over an iron catalyst at around 450 degrees and 200 atmospheres pressure
2) this causes some of the nitrogen and hydrogen atoms to react forming ammonia
3) this is a reversible reaction as some of the ammonia can be broken down into nitrogen and hydrogen

106
Q

how can we increase the yield of the haber process

A
  • by cooling the ammonia and turning it into a liquid which is removed, we can then recycle the unreacted nitrogen and hydrogen back over the catalyst
107
Q

what does le chatelliers principle state

A
  • if a system is at equilibrium and a change is made to any of the conditions then the system responds to counteract the change
108
Q

how do we change the conditions to produce a higher yield in the haber process

A

by using le chatelliers principle:
- you can adjust the temperature and the pressure to shift the position of the equilibrium towards the right hand side, to produce more ammonia, but as the forward reaction is exothermic a cool temperature will shift the equilibrium to the right this means that the reaction will be slow, this is why 450 degrees is the compromise temperature (perfect temp) as we get a relatively fast reaction and a relatively high yield
- the iron catalyst increases the rate of reaction
-

109
Q

how do we change the conditions to produce a higher yield in the haber process

A

by using le chatelliers principle:
- you can adjust the temperature and the pressure to shift the position of the equilibrium towards the right hand side, to produce more ammonia, but as the forward reaction is exothermic a cool temperature will shift the equilibrium to the right this means that the reaction will be slow, this is why 450 degrees is the compromise temperature (perfect temp) as we get a relatively fast reaction and a relatively high yield
- the iron catalyst increases the rate of reaction
-pressure - a high pressure will push the equlibrium to the right side

110
Q

what do fertilisers do

A

replace the elements taken up by plants

111
Q

what do NPK fertilisers contain

A

compounds of :
- nitrogen
- phosphorus
- potassium
these improve agricultural productivity

112
Q

where are NPK fertilisers produced

A

large industrial facilties

113
Q

what are NPK fertillisers

A

formulations of different salts

114
Q

what di the salts contain in NPK fertilisers

A

the required elements needed by the plants

115
Q

what is the main compound of nitrogen in NPK fertilisers

A

ammonium nitrate

116
Q

how is ammonium nitrate made for the nitrogen in NPK fertilisers

A
  • we produce the ammonia from the haber process, then use the ammonia to produce nitrate, then react the nitric acid with more ammonia to make ammonium nitrate
117
Q

where does the potassium come from in NPK fertilisers

A

it comes from potassium chloride or sulfate, which are both mined from the ground and can be used without any further processes

118
Q

how is the phosphate rock chemically processed before being used in NPK fertilisers (nitric acid)

A

1) we treat the phosphate rock with nitric acid this produced phosphoric acid and calcium nitrate
2) as the phosphoric acid as contains phosphorus we cannot add it directly to the plants so we neutralise it with ammonia
3) this produces ammonium phosphate which can be used in NPK fertilisers

119
Q

how is the phosphate rock chemically processed before being used in NPK fertilisers (sulfuric acid)

A

1) treat the phosphate rock with sulfuric acid to produce a mixture of calcium phosphate and calcium sulfate, this mixture is called single superphosphate
2) this can be used in NPK fertilisers

120
Q

how is the phosphate rock chemically processed before being used in NPK fertilisers (phosphoric acid)

A

1) treat phosphate rock with phosphoric acid to produce triple superphosphate
2) this can be used in NPK fertilisers

121
Q

in what ways is phosphate rock treated

A
  • nitric acid
  • phosphate acid
  • sulfuric acid
122
Q

how is ammonium nitrate made in a school lab compared to an industry

A
  • in a school lab we use dilute solutions of ammonia and nitric acid, to make it safe to work with
  • whilst in an industry the ammonia is a gas and the nitric acid is concentrated, this is much more dangerous as the reaction is very exothermic, the heat produced has to be safely removed and this heat is then used in later stages
    /////////////////////////////////////////////////////////////////
  • in a lab we produce crystals using a water bath and a bunsen burner and this requires a lot of heat energy
  • whilst in an industry some of the energy for evaporation is provided by the exothermic reaction
    //////////////////////////////////////////////////////////////////
  • in a lab we can only produce a small amount of ammonium nitrate in one go ( called a batch process)
  • whilst in industry the chemical is produced by a continuous process so thousands of Kg can be produced easily

chemistry (13 decks)

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