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ZZ Chem 2 > using resources > Flashcards

using resources Flashcards

1
Q

Why do we use the Earth’s resources?

A
  • We use them to provide warmth, shelter, food and transport
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2
Q

What do natural resources provide?

A
  • Natural resources, supplemented by agriculture, provide food, timber, clothing and fuels
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3
Q

Define a natural resource

A
  • Anything that comes from the earth, sea or air formed without human input
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4
Q

What can natural products be replaced by?

A
  • Synthetic products or improved upon by man-made processe
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5
Q

Explain the importance of chemistry in improving agricultural and industrial processes

A
  • To provide new products
  • Promote sustainable development
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6
Q

Define sustainable development

A
  • Development that meets the needs of current generations without compromising the ability of future generations to meet their own needs
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7
Q

How can we apply sustainable development?

A
  • Reduce the use of a finite resource so it is more likely to last longer
  • Develop and adapt processes to use lower amounts of finite resources and reduce damage to the environment
  • e.g. catalysts that reduce the amount of energy required for certain industrial processes
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8
Q

Define renewable energy resources

A
  • Sources of power that quickly replenish
    themselves and can be used again
  • (only includes plants/wood if they continue to be re-planted)
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9
Q

Define finite resources

A
  • Have a limited supply that will eventually run out
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10
Q

Define potable water

A
  • Potable water= water that is safe to drink
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11
Q

Explain why potable water is not pure

A
  • Potable water is not ‘pure’ because it contains dissolved substances
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12
Q

Describe what makes potable water safe

A
  • It must have sufficiently low levels of dissolved salts and microbes
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13
Q

Name the factors that affect the methods used to produce potable water

A
  • Available supplies of water
  • Local conditions.
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14
Q

Explain the production of potable water in the UK

A
  • An appropriate source of fresh water is selected (rain provides water with low levels of dissolved substances and this collects in the ground/rivers/lakes)
  • When it rains, water can be collected as surface water or groundwater
  • The water is passed through filter beds to remove different sized insoluble solids
  • The water is then sterilised, to kill microbes
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15
Q

Name the sterilizing agents used to sterilize water

A
  • Ozone, UV light or chlorine
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16
Q

Describe how potable water can be obtained from sea/salty water

A
  • If only salty/sea water is available, desalination is required
  • can be done by distillation
  • or can be done using processes with membranes (e.g. reverse osmosis)
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17
Q

Explain how potable water is obtained by using distillation

A
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18
Q

Explain how potable water is obtained by using membranes

A
  • Reverse osmosis, membrane only allows water molecules to pass through
  • Ions and larger molecules are trapped by the membrane
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19
Q

What are the disadvantages of using desalinization to obtain potable water?

A
  • BOTH are very expensive
  • Not practical for producing large quantities of fresh water
  • Requires lots of energy
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20
Q

Describe the characteristics of water of the correct quality

A
  • Essential for life
  • It must be free of poisonous salts and harmful microbes.
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21
Q

Where can waste water come from?

A
  • Flush water down the drain, go towards sewers
  • Agricultural systems produce waste water including nutrient run off from fields and slurry from animal farms
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22
Q

What must be done to waste water?

A
  • Treated to remove organic matter and harmful microbes otherwise they would be very polluted and pose health risks
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23
Q

Explain how correct quality water is produced through waste water treatment

A
  1. Water is passed through a mesh screen
    to remove large solid particles e.g. twigs or grit
  2. Chemicals are added to make solids and
    microbes stick together to form sediment and sink (sedimentation) - heavier suspended solids sink to bottom
  3. When the sediment sinks to the bottom of the tank it forms sewage sludge while the lighter liquid (effluent) remains above
  4. The sewage sludge is dried and is then anaerobically digested by microorganisms in the absence of oxygen (releases methane gas)
  5. The effluent is removed and is aerobically digested by microorganisms in the presence of oxygen to remove organic matter and harmful microbes. (air is pumped through the water)
  6. The water is then sterilized with chlorine to kill any microbes left.
  7. Addition stages of treatment may involve adding chemicals, UV radiation or using membranes
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24
Q

What can the dried sludge be used as?

A
  • Dried sludge can be used as fertiliser
  • The digestion of sewage sludge removes organic matter and produces biogas used to make electricity
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25
Q

Compare waste water treatment and desalinisatoin

A
  • It is relatively cheaper and easier to obtain potable water from groundwater and wastewater than salt water, although seawater is a plentiful raw material, so is
    good for countries with little fresh water
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26
Q

Describe the Earth’s resources of metal ores

A
  • Earth’s resources of metal ores are limited
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27
Q

How are scientists extracting copper?

A
  • Copper ores are becoming scarce
  • Scientists have developed new ways of extracting copper from low-grade ores
  • These methods avoid traditional mining methods of digging, moving and disposing of large amounts of rock
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28
Q

Name the alternative methods used to extract copper

A
  • Smelting and electrolysis
  • Electrolysis of copper salt solutions
  • Displacement of copper salt solutions w/ scrap iron
  • Bioleaching to make solution + electrolysis or displacement
  • Phytomining
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29
Q

Explain how smelting + electrolysis is used to extract copper

A
  • Heat (roast) copper ore very strongly in a furnace with air to produce crude (impure) copper.
  • The copper compound reacts with the O2 gas in air
  • copper (I) sulfide + oxygen → copper + sulfur dioxide
  • Electrolysis is used to purify the impure copper extracted by smelting.
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30
Q

Explain how electrolysis of copper salt solutions is used to extract copper

A
  • Add sulfuric acid to copper ore to get copper sulfate
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31
Q

Explain how displacement of copper salt solutinos w/ iron is used to extract copper

A
  • Place iron nail in blue copper sulphate solution
  • Leave for one week to allow the reaction to take place
  • Solution turns into green iron sulphate solution
  • Copper metal forms on iron nail
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32
Q

Explain how phytomining is used to extract copper

A
  • Phytomining uses plants to absorb metal compounds from low-grade ores as they grow ( soils that contain copper which build up in the leaves)
  • Plants are harvested and then burned to produce ash that contains metal compounds which can be extracted
  • Copper irons are leached (dissolved) from ash by adding sulfuric acid to copper sulfate solution
  • Then electrolysis or displacement of copper salt solutions is used to extract pure copper
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33
Q

Explain how bioleaching is used to extract copper

A
  • Bioleaching uses bacteria to produce leachate solutions that contain metal compounds
  • Leachate contains copper ions which can be extracted by electrolysis or displacement
  • Converts copper compounds in the ore into soluble copper compounds, separating copper ore in the process
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34
Q

Explain how processing metal compounds is used to extract copper

A
  • The metal compounds can be processed to obtain the metal
    *For example, copper can be obtained from solutions of copper compounds by displacement using scrap iron or by electrolysis
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35
Q

What is the purpose of the life cycle assessment?

A
  • These are carried out to assess the environmental impact of products in different stages
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36
Q

What are the stages in the LCA?

A
  • Extracting and processing raw materials
  • Manufacturing and packaging
  • Use and operation during its lifetime
  • Disposal at the end of its useful life, including transport and distribution
    at each stage
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37
Q

What is the problem with using the LAC?

A
  • Use of water, resources, energy sources and production of some wastes can be
    fairly easily quantified
  • Allocating numerical values to pollutant effects is less straightforward and
    requires value judgements, so LCA (life cycle assessment) is not a purely
    objective process
  • Selective or abbreviated LCAs can be devised to evaluate a product but these can
    be misused e.g. in support of claims for advertising purposes
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38
Q

How can we reduce our use of resources?

A
  • Reduction in use
  • Reusing
  • Recycling
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39
Q

What are the benefits of reducing our use of resources?

A
  • Reduces the use of limited resources, use of energy sources, waste and environmental impacts
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40
Q

What are metals, glass, building materials, clay ceramics and most plastics produced from and what is its effect?

A
  • Metals, glass, building materials, clay ceramics and most plastics are produced
    from limited raw materials.
  • Much of the energy for the processes comes from limited resources
  • Obtaining raw materials from the Earth by quarrying and mining causes
    environmental impacts
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41
Q

Define ceramics

A
  • Non metal solids with high melting points that aren’t made from carbon-based compounds
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42
Q

How are clay ceramics made?

A
  • Can be made from clay
  • When fired at high temps, hardens to form a clay ceramic
  • Made by shaping wet clay and
    then heating in a furnace
43
Q

Describe clay

A
  • Soft material when dug up out of the ground, can be moulded into different shapes
  • Ability to be moulded when wet and then hardened makes it ideal for making pottery and bricks
44
Q

What are the uses / properties of ceramics?

A
  • Glass and clay ceramics such as porcelain and bricks
  • Insulators of heat and electricity
  • Brittle and stiff
45
Q

Give another example of ceramics

A
  • Glass
  • Glass is generally transparent - can be moulded when hot and brittle when thin
46
Q

Describe how soda-lime glass is made

A
  • Made by heating a mixture of sand, sodium carbonate and limestone (most commonly used glass) until it melts
  • When mixture cools, forms glass
47
Q

Describe how borosilicate glass is made

A
  • Made from sand and boron trioxide, melts at higher temperatures than soda-lime glass
  • Higher m.p. than soda lime
  • Made in the same way as soda lime
48
Q

Why is recycling metals better than mining new metals?

A
  • Uses less energy
  • Cuts down amount of waste sent to landfills
  • Conserves finite amount of meta in the earth
49
Q

Describe how glass bottles can be reused and recycled

A
  • Glass bottles can be crushed and melted to make different glass products, or insulating glass wool for wall insulation
  • Usually glass is separated by colour and chemical composition before being recycled
  • Can be reused without shaping
50
Q

What happens to the products that cannot be reused?

A
  • Other products cannot be reused and so are recycled for a different use
51
Q

Describe how metals can be recycled

A
  • Metals can be recycled by melting and recasting or reforming into different
    products
52
Q

Name the factors that affect the amount of separation required for recycling

A
  • Depends on the material
  • Depends on the properties required of the final product
  • e.g. some scrap steel can be added to iron from a blast furnace to reduce the amount of iron that needs to be extracted from iron
    ore
53
Q

Why are most metals in everyday use alloys?

A
  • Pure copper, gold, iron and aluminium
    are all too soft for everyday uses and so are mixed with small amounts of similar
    metals to make them harder for everyday use.
  • Disrupts the structure making it harder than pure metals
54
Q

Describe gold alloys

A
  • Gold in jewellery is usually an alloy with silver, copper and zinc and the
    gold purity is measured in carats
  • Pure gold is 24 carat (24/24)
55
Q

Describe bronze alloys

A
  • Bronze is an alloy of copper and tin
  • Used in electrical connectors, medals, statues
  • Bronze is harder than copper
56
Q

Describe brass alloys

A
  • Brass is an alloy of copper and zinc - used for tools
  • Brass is more malleable than bronze, used in situations where lower friction is required
57
Q

Describe steel alloys

A
  • Steels are alloys since they used mixtures of carbon and iron
58
Q

Describe the different types of steel alloys

A
  • Some steels contain other metals. Alloys can be designed to specific uses.
  • Low-carbon steels are easily shaped - used for sheeting (malleable)
  • High carbon steels are hard - used for cutting tools
  • Stainless steels (containing chromium and nickel) are resistant to
    corrosion - used for cutlery
59
Q

Describe aluminium alloys

A
  • Aluminium alloys are low density - used for aircraft
  • Pure aluminium too soft, so alloyed to make it stronger
60
Q

Define corrosion

A
  • Where metals react with substances in their environment and are gradually destroyed
  • Only happens on the surface of a material when exposed to air
61
Q

Describe the corrosion of iron

A
  • Corrodes easily (rusts)
  • Must be in contact with oxygen and water (present in air)
  • iron + oxygen + water –> hydrated iron (III) oxide
  • Rust is a soft crumbly solid that flakes off - leaves more iron to rust again, means object corrodes away
62
Q

Describe the corrosion of aluminium

A
  • Corrodes when exposed to air
  • Unlike iron, aren’t completely destroyed by corrosion
  • Aluminium oxide that forms doesn’t flake away
  • Forms a protective layer that sticks firmly to aluminum to stop any further reaction
63
Q

How can you show that bother oxygen and water are needed for iron to rust?

A
  • To show that water alone is not enough, put iron nail in a boiling tube with just water - nail won’t rust (water is boiled to remove oxygen and oil is used to stop air getting in)
  • To show oxygen alone is not enough, put iron nail in tube with just air, nail won’t rust (calcium chloride used to absorb water from air)
  • Put iron nail with air and water it will rust (mass of rusty nail increase as iron atoms have bonded to oxygen and water molecules)
64
Q

How can you prevent rusting?

A
  • Coat the iron with a BARRIER to keep water and oxygen out
  • Sacrificial method
  • OR BOTH
65
Q

How can you form a barrier to prevent rusting?

A
  • Coating with plastic - ideal for big and small structures
  • Electroplating - using electrolysis to reduce metal ions onto an iron electron, used to coat iron with a layer of a different material
  • Oiling/ Greasing - used when moving parts are involved, e.g. bike chains
66
Q

How can you prevent rusting using a sacrificial method?

A
  • Place a more reactive metal, such as zinc or magnesium with iron
  • Water and oxygen react with sacrificial metal instead of iron
67
Q

How can you use sacrificial method and barrier to prevent rusting?

A
  • Object can be galvanised by spraying it with a coating of zinc
  • Zinc layer firstly protective, but if scratched, zinc around site of scratch works as a sacrificial metal
68
Q

What are the uses / properties of metals?

A
  • Malleable and good conductors of heat and electricity
  • Ductile, shiny and stiff
  • Used in electrical wires, cutlery, car bodywork
69
Q

Name the factors that can affect the properties of polymers

A
  • Depends on what monomers they are made from
  • Depends on conditions under which they are made (catalysts and reaction conditions, e.g. pressure and temp)
70
Q

Describe low density poly(ethene)

A
  • Made at a moderate temp under high pressure
  • It is flexible and used for bags and bottles
  • Has weaker forces of attraction as the
    chains are further apart, meaning it has a low melting point and is
    soft
71
Q

Describe high density poly(ethene)

A
  • Made at lower temps and pressure with a catalyst
  • Has higher forces of attraction, as the chains are closer together, giving it a higher melting point
  • More rigid and used for water tanks and drain pipes
72
Q

Describe the structure of thermosoftening polymers

A
  • Thermosoftening polymers are made of individual, tangled polymer chains which
    are easily separated and are melted by heat
73
Q

Explain why thermosoftening polymers are easily separated and melted by heat

A
  • There are weak intermolecular forces between the chains
  • The chains are easy to separate
  • At lower temperatures
  • Less heat energy is needed to break the chains
74
Q

Describe the structure of thermosetting polymers

A
  • Thermosetting polymers consist of polymer chains, which cross links
  • Holds chain together in solid structure
  • Do not melt when heated.
  • Strong and rigid
75
Q

What are the uses / properties of poylmers?

A
  • Insulators of heat and electricity
  • Flexible and easily moulded
  • Applications in clothing and insulators in electrical items
76
Q

How are composites made?

A
  • Most composites are made of two materials embedded in each other
  • Fibres or fragments of a material are surrounded by, a matrix or binder binding together fibres or fragments of the other material, which is called the
    reinforcement
77
Q

What do the properties of a composite depend on?

A
  • Properties of the material its made from
78
Q

Give examples of composite materials

A
  • Bricks and pottery (both are very hard but very brittle)
  • Fibreglass
  • Carbon fibre
  • Concrete
  • Wood
79
Q

Describe fibre glass

A
  • Consists of fibres of glass embedded in a matrix made of polymer
  • Low density but very strong
  • Used for skis, surfboards and boats
80
Q

Describe carbon fibre

A
  • Have a polymer matrix
  • Reinforcement is either made from long chains of carbon atoms bonded together or carbon nanotubes
  • Strong and light
  • Used in aerospace and sports car manufacturing
81
Q

Describe concrete

A
  • Made from aggregate embedded in cement
  • Strong
  • Used as a building material
82
Q

Describe wood

A
  • Natural composite of cellulose fibres held together by an organic polymer matrix
83
Q

What is the Haber process used for?

A
  • Used to manufacture ammonia, which is used to produce nitrogen-based
    fertilisers
84
Q

Name the two raw materials used in the Haber process

A
  • Nitrogen
  • Hydrogen
85
Q

How is nitrogen obtained in the Haber process?

A
  • Nitrogen is obtained from the air
86
Q

How is hydrogen obtained in the Haber process

A
  • Hydrogen may be obtained from natural
    gas (methane) or other sources.
  • Reacts with steam to form hydrogen and CO2
87
Q

Explain the Haber process

A
  • The purified gases are passed over a catalyst of iron at a high temperature
    (about 450 °C) and a high pressure (about 200 atmospheres).
  • Some of the hydrogen and nitrogen reacts to form ammonia.
  • The reaction is reversible so ammonia breaks down again into nitrogen and
    hydrogen. (eventually reaches dynamic equilibrium)
  • Ammonia formed as a gas but on cooling, the ammonia liquefies and is removed.
  • The remaining nitrogen and hydrogen are recycled.
  • Ammonia produced can be used to make ammonium nitrate (nitrogen-rich fertiliser)
88
Q

State the word equation for the Haber process

A
  • nitrogen + hydrogen ⇋ ammonia
89
Q

State the symbol equation for the Haber process

A
  • N2 + 3H2 ⇋ 2NH3
90
Q

What state is the Haber process in?

A
  • The Haber Process is in dynamic equilibrium
  • The forward and backward reactions keep going once equilibrium is reached
91
Q

What happens if you increase/ decrease the pressure in the Haber Process?

A
  • There are less moles of gas on the product side (2 compared to 4), this means you would increase pressure to move equilibrium to the right so more ammonia is produced
  • Increase in pressure, increases the yield of ammonia and rate of reaction
92
Q

What happens if you increase/decrease the temperature in the Haber Process?

A
  • Forward reaction is exothermic - increase temp will move equilibrium away from ammonia
  • Low temps would favour forward reaction - yield of ammonia would be greater at lower temps
93
Q

Why are the actual conditions used in the Haber Process not very low temps and very high pressure?

A
  • Low temperature leads to a reaction rate that is too slow
  • Very high pressure requires too much energy
94
Q

Why do farmers use formulated fertilisers instead of manure?

A
  • Do not smell, more widely available, easier to use, have enough of each nutrient so more crops can grow
95
Q

What are the three main elements in NPK fertilisers?

A
  • Production and uses of NPK fertilisers
  • Compounds of nitrogen, phosphorus and potassium are used as fertilisers to
    improve agricultural productivity
96
Q

What are NPK fertilisers?

A
  • Formulations containing salts of nitrogen, phosphorus and potassium in the right percentages of elements
97
Q

How can industrial production of NPK fertilisers be achieved?

A
  • Industrial production of NPK fertilisers can be achieved using a variety of raw
    materials in several integrated processes
98
Q

How is ammonia used to produced nitrogen-containing compounds?

A
  • Reacted with oxygen and water in a series of reactions to make nitric acid
  • React ammonia with acids to get ammonium salts which can be used as fertilisers
99
Q

Describe the reaction of ammonia and nitric acid

A
  • Produce ammonium nitrate
  • Good be use has nitrogen from two sources
    NH3 + HNO3 –> NH4NO3
100
Q

How can ammonium nitrate be produced in the industry?

A
  • Reaction carried out in giant vats at high concs resulting in exothermic reaction
  • Heat released is used to evaporate water to make a very concentrated ammonium nitrate product
101
Q

How can ammonium nitrate be produced in the lab?

A
  • Carried out on a much smaller scale by titration and crystallisation
  • Lowed concentration than industry, so less heat is produced and is safer
  • After titration, mixture is crystallised to give pure ammonium nitrate crystals
  • Crystallisation isn’t used in industry because it’s very slow
102
Q

How can we obtain a source of potassium

A
  • Mining potassium chloride and potassium sulfate
  • Phosphate rock is also mined but the phosphate salts in rocks are insoluble so the plant’s can’t directly absorb them and use them as nutrients
103
Q

How can you make phosphate rock soluble to be used as a fertiliser?

A
  • Phosphate rock is treated with nitric acid to produce phosphoric acid and calcium nitrate
  • Or sulfuric acid to produce calcium sulfate and calcium phosphate (single superphosphate
  • These are soluble salts
  • Reaction with phosphoric acid only produces calcium phosphate (triple superphosphate)

ZZ Chem 2 (5 decks)

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