Chemistry - using resources Flashcards
1
Q
What are ceramics
A
Non metal solids with high melting points that aren’t made from carbon-based compounds. Some ceramics can be made from clay
2
Q
What is clay
A
A soft material when dug up out the ground - can be moulded into different shapes
3
Q
How does clay form ceramics
A
When it’s fired at high temperatures it hardens to form a clay ceramic
4
Q
Characteristics of glass
A
Example of ceramic
generally transparent
can be moulded when hot
can be brittle when thin
5
Q
How is soda-lime glass made
A
Made by heating a mixture of limestone, sand and sodium carbonate until it melts. When the mixture cools it comes out as glass
6
Q
What are composites
A
Usually made of one material embedded in another. The properties of a composite depend on the material its made from
7
Q
Borosilicate glass compared to soda - lime glass
A
Has a higher boiling point - useful for objects that require heating eg. kitchenware or labware
8
Q
How is boron silicate glass made
A
Made by melting a mixture of sand and boron trioxide
9
Q
Features of composities
A
- Reinforcements which consits of fibres or fragments of one material
- Matrix or binder surrounds the reinforcement
10
Q
Carbon fire composites
A
Have a polymer matrix
Reinforcement made from either long chains of carbon atoms bonded together or from carbon nanotubes
Very strong and light - used in aerospace and sports car manufacturing
11
Q
Concrete
A
Made from aggregate (a mixture of sand and gravel)
embedded in cement
Very strong - ideal for building houses
12
Q
Wood
A
- natural composite of cellulose fibres
- organic polymer matrix
13
Q
Fibreglass
A
- fibres of glass
- matrix made of polymer
- low density
- very strong
- used for skis, boats and surfboards
14
Q
What do the properties of polymers depend on
A
- The monomer (what its made from)
- The conditions used to make the polymer (how its made)
15
Q
Thermosoftening polymers
A
Melt when we heat them
Can be reshaped while their soft
Go back to a solid when we cool them back down
16
Q
How could you change the properties of polymers
A
- the reaction pressure
- the reaction temperature
- the catalyst
17
Q
Why can thermosoftening polymers be easily melted
A
They contain individual polymer chains entwined together with weak forces between the chains.
18
Q
Thermosetting polymers
A
- do not melt when we heat them
- strong, hard and rigid
19
Q
Why do thermosetting polymers not melt
A
Contain monomers that can form cross links between the polymer chains, holding the chains together in a solid structure.
20
Q
Definition of corrosion
A
The destruction of materials by chemical reactions with substances in the environment
21
Q
What does rusting only apply to
A
Iron and alloys of iron such as steel
22
Q
What is needed for iron to rust
A
Iron needs to be in contact with both oxygen and water which are present in air
23
Q
When does aluminium corrode
A
Aluminium corrodes when exposed to air
24
Q
Difference between corrosion of iron and corrosion of aluminium
A
Unlike iron objects, things made from aluminium aren’t completely destroyed by corrosion. This is because aluminium oxide doesn’t flake away and instead forms a protective layer that sticks to the aluminium and stops and further reaction taking place
25
Describe an experiment that shows both oxygen and water are needed for iron to rust
- If you put an iron nail in a boiling tube with just water it won't rust (the water is boiled to remove oxygen and oil is used to stop any oil getting in it)
- If you put an iron nail in a boiling tube with just air it won't rust (calcium chloride can be used to absorb any water from the air)
- However if you put an iron nail in a boiling tube with air and water it will rust
26
Ways to prevent rusting
- coat iron with a barrier to keep out the water and oxygen eg. paint/coat with plastic, electroplating, oiling/greasing
- sacrificial method
27
Sacrifical method of preventing rusting
Involves placing a more reactive metal such as zinc or magnesium with the iron. Water and oxygen then react with the sacrificial metal instead of the iron.
28
Where do natural resources come from
Earth, sea and air
29
Natural resources meaning
Form without human input
30
Renewable resources
Reform at a similar rate to, or faster than, we use them.
31
Finite resources
Aren't formed quickly enough to be considered replaceable.
32
Examples of finite resources
- Fossil fuels
- Nuclear fuels (uranium and plutonium)
33
After being extracted what happens to many finite resources and examples
they undergo man-made processes to provide fuels and materials necessary for modern life. Eg. fractional distillation is used to produce usable products such as petrol from crude oil and metal ores are reduced to produce a pure metal.
34
Risks of extracting finite resources
- Uses loads of energy
- Scars the landscape
- Produces lots of waste and destroys habitat
35
Sustainable development
Development that meets the needs of current generations without compromising the ability of future generations to meet their own needs
36
Way of reducing the use of finite resources
- Using them less
- Chemists can develop and adapt processes that use lower amounts of finite resources
37
Way to improve coppers sustainability
Extracting it from low-grade ores (ores without much copper in).
We can do this by Bioleaching or Phytomining
38
Bioleaching
Bacteria are used to convert metal compounds into soluble metal compounds separating out the metal from the ore in the process. Produces leachate solutions that contain metal compounds.
39
Phytomining
Uses plants to absorb metal compounds from the soil. The plants are harvested and then burned to produce ash that contains the metal compound.
40
Disadvantage of bioleaching or phytomining
They are slow
41
Why is recycling metals important
Mining and extracting metals takes lots of energy most of ewhich come from burning fossil fuels
Recycling metals uses much less energy as it conserves the finite amount of each metal and cuts down on the amount of waste getting sent to landfill
42
How are metals usually recycled
By melting them and then casting them into the shape of the new product
43
How can glass recycling help sustainability
Reduces the amount of energy needed to make new glass products, and also the amount of waste created when used glass is thrown away.
44
How can glass be recycled
Glass is separated by colour and chemical composition before being recycled
The glass is crushed then melted to be reshaped for use in glass products such as bottles or jars.
45
Life cycle assessments
Looks at every stage of a products life to show the impact it would have on the environment
46
Issues with getting raw materials
- Extracting raw materials needed for a product can damage the local environment
- Raw materials often need to be processed to extract the desired materials and this often needs large amounts of energy
47
Issues with manufacturing and packaging
- Manufacturing products and their packaging can often take up a lot of energy resources and can cause a lot of pollution
- Waste products and disposing of them
48
Issues with using the product
Can damage the environment
How long a product is used for or how many uses - products that need lots of energy to produce but are used for ages mean less waste in the long run
49
Issues with product disposal
Products are often disposed of in landfill sites - takes up space and pollutes land and water
Energy is used to transport waste to landfill, which causes pollutants to be released into the atmosphere
Products might be incinerated which causes air pollution
50
Raw materials of plastic bag compared to paper bag
Plastic bag - Crude oil
Paper bag - Timber
51
Manufacturing and packaging of plastic bag
Plastic bag - Compounds extracted from crude oil by fractional distillation. Waste is reduced as other fractions of crude oil have other uses.
Paper bag - Pulped timber is processed using lots of energy. Lots of waste is made
52
Using plastic bag vs paper bag
Plastic bags - Can be reused and be used for other things as well as shopping like bin liners
Paper bags - Usually only used once
53
Plastic vs paper bag disposal
Plastic bag - recyclable but not biodegradable so will take up space in landfill
Paper bag - Biodegradable, non toxic and can be recycled.
54
Problems with life cycle assessments
The effect of some pollutants is hard to give a numerical value
Producing an LCA is not an objective method as it takes into account the values of the person carrying out the assessment - can be bias
Can be used for positive advertising
55
Potable water
Water that is naturally safe for humans to drink - levels of dissolved water aren't to high and no bacteria or microbes in it
56
Pure water
Water. that only contains H20 molecules
57
Way potable water is produced in the UK
Rainwater collects in the ground in aquifers , and in lakes rivers and reservoirs which are all good sources of fresh water. Then pass water through filter beds. then sterilise using chlorine
58
What do we use filter beds for
To remove materials such as leaves and suspended particles.
59
Why do we sterilize the water
To kill microbes
60
Why do we use rainwater as a source of water
It has very low levels of dissolved minerals
61
How do very dry counties get water
Use sea water. Potable water is produced by desalination. Use distillation or reverse osmosis. Reverse osmosis is whereby salty water is passed through a membrane that only allows water molecules to pass through.
62
What does desalination do
Reduces the levels of dissolved minerals down to an acceptable level for potable water
63
Problems of distillation and reverse osmosis
They need loads of energy, so they're really expensive.
64
Why does sewage have to be treated
To remove any organic matter and harmful microbes before it can be put back into fresh water sources
65
First step of sewage treatment
Screening - this involves removing any large bits of materials well as any grit
66
Second step of sewage treatment
Stands in settlement tank and undergoes sedimentation - the heavier suspended solids sink to the bottom to produce sludge and lighter effluent floats to the top
67
Third step of sewage treatment
The effluent in the settlement tank is removed and treated by biological aerobic digestion. This is when air is pumped through the water to encourage aerobic bacteria to break down any organic matter.
68
Fourth step of sewage treatment
Sludge from the bottom, of the settlement tank is removed into large tanks. gets broken down by anaerobic digestion. Releases methane in the process.
69
What are needed to make ammonia
Nitrgogen and Hydrogen
70
Reaction of ammonia
N2 + 3h2 <---------> 2NH3 (+heat)
71
Why is the harbour process well suited for an industrial scale
Reactants aren't too difficult or expensive to obtain
72
How is nitrogen obtained
From the air
73
How is hydrogen obtained
From reacting methane with steam to formn hydrogen and co2
74
What catalyst is used for the harbour process
Iron
75
Conditions for harbour process
- High temp (450 degrees)
- High pressure (200 atmospheres)
76
In the harbour process what state is the ammonia
Original formed as a gas but as it cools in the condenser it liquifies and is removed.
77
Why is temp compromised
The forward reaction in the Harbour process is exothermic which means increasing temp will move the equilibrium the wrong way - towards nitrogen and hydrogen. Yield of ammonia would be greater at lower temps.
- However 450 degrees is used so that there is another kinetic energy to overcome the activation energy
78
Why is pressure compromised
Higher pressures move the position of equilibrium towards the products as this is the side with the fewer moles. So increasing pressure maximises the percentage yield. However it cannot be too high as the process could be too expensive or dangerous to build and maintain.
79
What do fertilisers allow
Allow us to keep growing crops on the same land every year
80
What compounds do NPK fertilisers contain
Compounds of phosphorous, nitrogen, and potassium
81
Why are formulated fertilisers better
- widely available
- easier to use- don't smell
- have just enough nutrient so more crops can be grown.
82
What do fertilisers do
They replace missing elements or provide more of them
83
How do phosphorus, nitrogen and potassium
They help to increase crop yield as the crops can grow faster and bigger. T
84
How are nitrogen containing compounds formed
Ammonia can be reacted with oxygen and water in a series of reactions to form nitric acid
Ammonia and nitric acid can react together to form ammonia nitrate which is especially good in fertilisers
85
How is potassium sourced
Potassium chloride and sulphate can be mined and used as a source of potassium
86
How is phosphate sourced
Phosphate rock is mined however because the phosphate salts in the rock are insoluble, plants cant use them as nutrients.
87
How to produce soluble phosphates
Reacting phosphate rock with :different types of acid
88
Single superphosphate
Sulphuric acid + phosphate rock -----> calcium sulphate + calcium phosphate
89
Triple superphosphate
Phosphate rock + phosphuric acid -----> calcium phosphate
90
What does phosphate rock and nitric acid produce
Phosphate acid and calcium nitrate
91
