C6 Flashcards
(208 cards)
1
Q
What are the essential elements needed by plants?
A
Nitrogen, phosphorus, and potassium are essential elements needed by plants.
2
Q
What happens if soil contains limited amounts of essential elements?
A
Plants grow poorly and crop yields suffer.
3
Q
What are fertilisers?
A
Fertilisers are substances that replace the elements used by plants as they grow.
4
Q
In what form can plant roots absorb essential elements?
A
Plant roots can only absorb these elements if they are in a water-soluble form.
5
Q
What are NPK fertilisers?
A
Fertilisers that provide nitrogen, phosphorus, and potassium in water-soluble compounds are called ‘NPK fertilisers.’
6
Q
What is the Haber process?
A
The Haber process manufactures ammonia from nitrogen and hydrogen.
7
Q
What is the balanced equation for the Haber process?
A
N₂(g) + 3H₂(g) → 2NH₃(g)
8
Q
What raw materials are needed for the Haber process?
A
The raw materials for the Haber process are air, natural gas, and steam.
9
Q
How is nitrogen obtained for the Haber process?
A
Nitrogen is manufactured by the fractional distillation of liquefied air.
10
Q
How is hydrogen produced for the Haber process?
A
Hydrogen is manufactured by reacting natural gas (mostly methane) with steam.
11
Q
Name some compounds produced in a fertiliser factory.
A
Compounds include ammonium nitrate, ammonium sulfate, ammonium phosphate, and potassium nitrate.
12
Q
Why are NPK fertilisers important to farmers?
A
NPK fertilisers are important because they provide essential nutrients that enhance crop yields.
13
Q
What are the essential elements needed by plants?
A
Nitrogen, phosphorus, and potassium are essential elements needed by plants.
14
Q
What happens if soil contains limited amounts of essential elements?
A
Plants grow poorly and crop yields suffer.
15
Q
What should you be able to describe after studying C6.1.2?
A
You should be able to describe how to make potassium sulfate and ammonium sulfate in the laboratory, and compare the industrial and laboratory production of fertilizers.
16
Q
What is urea and how is it produced?
A
Urea is found in urine and can be manufactured by reacting ammonia with carbon dioxide. It has the highest nitrogen content of all common fertilizers.
17
Q
What are the two compounds that can be made in the laboratory as fertilizers?
A
Potassium sulfate and ammonium sulfate.
18
Q
How is potassium sulfate made in the laboratory?
A
It is made from potassium hydroxide and sulfuric acid.
19
Q
What is the first step in making ammonium sulfate?
A
Place dilute ammonia solution in a conical flask with methyl orange indicator.
20
Q
What happens when you add sulfuric acid in the preparation of ammonium sulfate?
A
The indicator changes from yellow to red at the end point.
21
Q
What should be done after reaching the end point in making ammonium sulfate?
A
Add a little extra ammonia solution to ensure the reaction is complete.
22
Q
What are some hazards associated with making ammonium sulfate?
A
Ammonia solution and potassium hydroxide solution are alkaline, and ammonia has an irritating sharp smell.
23
Q
How do industrial processes differ from laboratory processes?
A
Laboratory processes usually make small amounts using a batch process, while industrial processes are continuous and produce large amounts.
24
Q
What is the starting material in laboratory fertilizer production?
A
Pure substances bought from chemical manufacturers.
25
What must be done to raw materials in fertilizer factories?
They must be purified before use or the product must be purified at the end.
26
Why might a fertilizer factory require more energy to make ammonium sulfate than a laboratory?
Factories operate on a larger scale and may have continuous processes that require more energy.
27
Why are batch processes more suited for making expensive specialty chemicals?
Batch processes allow for precise control and production of small quantities, which is ideal for expensive specialty chemicals.
28
What are the conditions chosen for the Haber process?
The conditions are usually: a pressure of 200 atmospheres (20MPa), a temperature of 450°C, and an iron catalyst.
29
What is the equilibrium yield of ammonia under the chosen conditions?
The equilibrium yield of ammonia is about 30%.
30
Why are the chosen conditions for the Haber process a compromise?
Higher pressure increases yield but is hazardous and expensive, while lower temperatures favor yield but slow the reaction rate.
31
What factors determine the pressure chosen in the Haber process?
The pressure is chosen based on the number of moles of gas; increasing pressure shifts equilibrium to the right, increasing yield.
32
What factors determine the temperature chosen in the Haber process?
The temperature is a compromise; lower temperatures favor yield, while higher temperatures increase reaction rate and catalyst efficiency.
33
What happens to the equilibrium yield of ammonia if the temperature is increased?
The equilibrium yield of ammonia decreases.
34
What happens to the equilibrium yield of ammonia if the pressure is increased?
The equilibrium yield of ammonia increases.
35
What is an environmental benefit of using ammonia as a fuel?
Ammonia is considered a 'green fuel' compared to petrol or diesel.
36
What is the effect of liquefying ammonia on the equilibrium yield of the Haber process?
Liquefying ammonia allows for its removal and recycling of unreacted nitrogen and hydrogen, improving overall yield.
37
What is the role of the iron catalyst in the Haber process?
The iron catalyst increases the rate of reaction, working more efficiently above 400°C.
38
What are the three raw materials needed for making sulfuric acid?
The three raw materials are sulfur, oxygen (from air), and water.
39
What happens in stage 1 of the Contact process?
In stage 1, sulfur burns in air to produce sulfur dioxide:
S(s) + O2(g) → SO2(g)
(AH = -297 kJ/mol)
## Footnote
This stage involves an exothermic reaction that is not reversible.
40
What is produced in stage 2 of the Contact process?
In stage 2, sulfur dioxide and oxygen react to produce sulfur trioxide:
2SO2(g) + O2(g) ⇌ 2SO3(g)
(ΔH = -144 kJ/mol)
41
What conditions are chosen for the reversible reaction in stage 2?
The conditions are usually a pressure of 2 atmospheres (200 kPa), a temperature of 450°C, and a vanadium(V) oxide catalyst.
42
What is the equilibrium yield of sulfur trioxide under the chosen conditions?
The equilibrium yield of sulfur trioxide is about 96%.
43
What is the balanced equation for the overall reaction in which sulfuric acid is formed?
The balanced equation is:
S(s) + O2(g) + 2H2O(l) → H2SO4(aq)
44
What factors determine the pressure chosen in stage 2?
The pressure is determined by the number of moles of gas: there are 3 moles of gas on the left and 2 moles on the right. Increasing pressure shifts the equilibrium to the right, increasing the yield of sulfur trioxide.
45
What factors determine the temperature chosen in stage 2?
The forward reaction is exothermic, so a low temperature favors high yield. The chosen temperature is a compromise to achieve a reasonable yield and rate of reaction.
46
What is the effect of increasing temperature on the equilibrium yield of sulfur trioxide?
Increasing temperature decreases the equilibrium yield of sulfur trioxide.
47
What is the effect of using a vanadium(V) catalyst on the reaction?
Using a vanadium(V) catalyst increases the rate of reaction without affecting the equilibrium yield.
48
What are the steps to control hazards in stage 3 of the Contact process?
1. Sulfur trioxide is passed through concentrated sulfuric acid to form oleum.
2. The oleum is then added to water to produce concentrated sulfuric acid.
49
What is produced when oleum is added to water?
The reaction produces a larger volume of concentrated sulfuric acid:
H2SO4(l) + H2O(l) → 2H2SO4(aq)
50
What should you be able to explain after studying C6.1.5 Making ethanol?
You should be able to explain how the commercially used conditions for an industrial process are related to the availability and cost of raw materials and energy supplies, control of equilibrium position, and rate of reaction.
51
What is ethanol used for?
Ethanol is used as an alcohol in wine and beer, as a fuel, as a solvent for perfume and deodorants, and to kill bacteria.
52
How is alcohol made from renewable raw materials?
Ethanol is made from plant sugars using fermentation, which relies on single-celled fungi called yeast.
53
What is the fermentation process equation?
Glucose is converted to carbon dioxide and ethanol: glucose → carbon dioxide + ethanol.
54
What conditions are required for fermentation?
Fermentation is carried out at about 35°C under normal atmospheric pressure.
55
What happens to yeast cells if the temperature is too low or too high?
Yeast cells become inactive if the temperature is too low, and their enzymes become denatured and stop working above about 50°C.
56
How is alcohol made from non-renewable raw materials?
Ethanol is obtained from crude oil, a non-renewable raw material, through the hydration of ethene.
57
What is the hydration reaction for ethene?
The reaction is: ethene + steam → ethanol.
58
What are the conditions needed for the hydration of ethene?
It requires a temperature of 300°C, a pressure of 60 atmospheres, and a phosphoric acid catalyst.
59
What are the differences in cost and conditions between fermentation and hydration of ethene?
Fermentation has a low cost of raw materials, moderate temperature, normal pressure, and a high rate of reaction, while hydration has a high cost of raw materials, high temperature, high pressure, and a high rate of reaction.
60
What factors influence the process chosen by a manufacturer for making ethanol?
Factors include the availability and cost of raw materials and the cost of the energy needed.
61
What is a sustainable development consideration for ethanol production?
The process for the manufacture of ethanol that is more suitable for sustainable development considers the raw materials and energy requirements.
62
What are two advantages of making ethanol from ethene and steam?
1. Higher efficiency in production. 2. More control over the reaction conditions.
63
What are two advantages of making ethanol by fermentation?
1. Utilizes renewable resources. 2. Lower energy requirements.
64
What should an alcohol company consider when choosing a method for large-scale ethanol production near farmland?
They should evaluate both methods for making ethanol and consider factors such as resource availability and sustainability.
65
What should you be able to explain after studying the lesson on extracting metals?
You should be able to explain how the industrial process used to extract a metal is chosen and describe how copper may be extracted from copper oxide.
66
How much copper is produced by the world's mines each year?
The world's mines produce 18 million tonnes of copper each year.
67
What is an ore?
An ore is a rock or mineral that contains enough metal (or metal compound) to make it economical to extract the metal.
68
What is the first stage in extracting copper from copper(II) sulfide?
The first stage is roasting copper(II) sulfide in air to produce copper(II) oxide and sulfur dioxide.
69
What is the balanced equation for the first stage of copper extraction?
2CuS(s) + 3O2(g) → 2CuO(s) + 2SO2(g)
70
What is the second stage in extracting copper from copper(II) oxide?
The second stage involves heating copper(II) oxide with carbon to produce copper and carbon dioxide.
71
What is the balanced equation for the second stage of copper extraction?
2CuO(s) + C(s) → 2Cu(l) + CO2(g)
72
What type of reaction occurs during the extraction of copper?
This is an example of a redox reaction.
73
What happens to copper(II) oxide during the extraction process?
Copper(II) oxide loses oxygen and is reduced.
74
What role does carbon play in the extraction of copper?
Carbon acts as a reducing agent.
75
What extraction methods are available for metals?
All metals could be extracted using electrolysis, but cheaper methods are used for less reactive metals.
76
Why is aluminium extracted using electrolysis?
Aluminium is extracted using electrolysis because it is more reactive than carbon.
77
What is the process for extracting copper using charcoal?
Mix copper(II) oxide and charcoal in a crucible, heat strongly, allow to cool, and separate the copper.
78
What safety precaution should be taken when extracting copper?
Eye protection should be worn.
79
What is the learning outcome of the lesson on extracting iron?
After studying this lesson you should be able to describe how iron may be extracted from iron oxide.
80
When was the world's first cast iron bridge opened?
The world's first cast iron bridge was opened in 1781.
81
What materials are used in a blast furnace?
The raw materials added to the top of the blast furnace are iron ore (such as haematite), coke, and limestone.
82
What is a blast furnace?
A blast furnace is a large reduction container used to extract iron from its ore.
83
How high can modern blast furnaces be and how much iron can they produce?
Modern blast furnaces can be around 30 m high and produce about 10,000 tonnes of iron per day.
84
What is the main reducing agent in a blast furnace?
Carbon monoxide is the main reducing agent in the blast furnace.
85
What is the first stage of the reaction in a blast furnace?
Coke burns in the hot air, making carbon dioxide: C(s) + O2(g) → CO2(g).
86
What is the second stage of the reaction in a blast furnace?
More coke reduces the carbon dioxide, making carbon monoxide: C(s) + CO2(g) → 2CO(g).
87
What happens in the third stage of the reaction in a blast furnace?
Carbon monoxide reduces iron(III) oxide to iron at around 1500°C: 3CO(g) + Fe2O3(s) → 3CO2(g) + 2Fe(l).
88
What impurities are removed from molten iron in a blast furnace?
Sandy impurities from the iron ore are removed using limestone.
89
What is the reaction that occurs when calcium carbonate decomposes in a blast furnace?
Calcium carbonate decomposes in high temperatures: CaCO3(s) → CaO(s) + CO2(g).
90
What reaction occurs between calcium oxide and silica?
The calcium oxide formed reacts with silica from the sandy impurities to form calcium silicate: CaO(s) + SiO2(g) → CaSiO3(l).
91
What is slag in the context of a blast furnace?
The molten calcium silicate is called slag; it floats on the molten iron.
92
What is the relative formula mass of Fe2O3?
The relative formula mass of Fe2O3 is calculated as follows: Fe = 55.8, O = 16.0, so Fe2O3 = 2(55.8) + 3(16.0) = 159.6.
93
What is the mass of iron oxide needed to produce 385 tonnes of iron?
To calculate the mass of iron oxide needed to make 385 tonnes of iron, use the stoichiometry of the reaction.
94
What is the name and formula of the main reducing agent in the blast furnace?
The main reducing agent is carbon monoxide, with the formula CO.
95
Write a balanced equation for the reduction of iron(III) oxide to iron.
The balanced equation is: 3CO(g) + Fe2O3(s) → 3CO2(g) + 2Fe(l).
96
Outline how iron is produced from iron(III) oxide in the blast furnace.
Iron is produced through redox reactions where carbon monoxide reduces iron(III) oxide to iron.
97
Explain why the reaction between calcium oxide and silica is a neutralisation reaction.
The reaction between calcium oxide and silica is a neutralisation reaction because it forms a salt (calcium silicate) from a base (calcium oxide) and an acid (silica).
98
What should you be able to explain after studying this lesson?
You should be able to explain why electrolysis is used to extract some metals from their ores.
99
What should you be able to describe after studying this lesson?
You should be able to describe how aluminium may be extracted from aluminium oxide.
100
What is aluminium mainly found as in nature?
Aluminium exists mainly as aluminium oxide, Al2O3, found in an ore called bauxite.
101
Why must aluminium be extracted by electrolysis?
Aluminium is more reactive than carbon, which means it must be extracted from its ore by electrolysis.
102
Why does electrolysis not work when aluminium oxide is in the solid state?
Electrolysis only works if the compound is in solution or molten, but aluminium oxide does not dissolve in water and has a very high melting point.
103
What is the melting point of aluminium oxide?
The melting point of aluminium oxide is over 2000°C.
104
How is aluminium oxide prepared for electrolysis?
Aluminium oxide is dissolved in molten cryolite, which has a much lower melting point than aluminium oxide.
105
What is the temperature at which electrolysis occurs for aluminium extraction?
Electrolysis occurs at about 950°C.
106
What materials are used in the electrolysis cell for aluminium extraction?
The electrolysis cell is made from steel lined with graphite.
107
What is produced at the cathode during electrolysis?
Aluminium is produced at the cathode.
108
What is produced at the anodes during electrolysis?
Oxygen is produced at the anodes.
109
What does the oxygen react with during electrolysis?
The oxygen reacts with the hot graphite anodes, making carbon dioxide.
110
What is the main factor determining the cost of extracting aluminium?
The cost of the electricity needed is the most important factor.
111
Why may the anodes in an aluminium electrolysis cell need to be replaced frequently?
The anodes may need to be replaced every few weeks due to the reaction with oxygen.
112
What happens at the cathode during the electrolysis of aluminium oxide?
At the cathode, Al^3+ + 3e^- → Al.
113
What happens at the anode during the electrolysis of aluminium oxide?
At the anode, 2O^2- → O2 + 4e^-.
114
Who independently worked out how to extract aluminium using electrolysis?
Charles Hall in America and Paul Héroult in France.
115
What causes the unusual color of the Rio Tinto river?
The river is colored red due to dissolved iron compounds from nearby metal mines.
116
What is acid mine drainage?
Acid mine drainage occurs when metal sulfides oxidize underwater, producing sulfuric acid that reacts with metal ores, forming soluble metal compounds.
117
What is bioleaching?
Bioleaching is a process where bacteria oxidize iron and sulfide ions, using the energy released to break down metal ores and release metal ions.
118
What type of reaction is involved in bioleaching?
Bioleaching involves oxidation reactions.
119
What are low-grade ores?
Low-grade ores are ores that contain too little metal for traditional mining methods to be profitable.
120
What are the environmental benefits of bioleaching?
Bioleaching does not release harmful sulfur dioxide into the atmosphere.
121
What is phytoextraction?
Phytoextraction is the process where plants absorb dissolved metal ions through their roots and accumulate them in their tissues.
122
How is metal extracted in phytoextraction?
Plants are harvested and burned to produce ash with a high concentration of metal, which can then be extracted.
123
What are the advantages of phytoextraction?
Phytoextraction is cheaper than traditional mining, produces less waste, and has a smaller energy transfer.
124
How does weather affect phytoextraction?
Weather can affect the growth of plants, which in turn impacts their ability to absorb metal ions.
125
What do the prefixes 'bio' and 'phyto' mean?
'Bio' refers to living things, while 'phyto' specifically refers to plants.
126
What are alloys?
An alloy is a mixture of two or more elements, at least one of which is a metal.
127
What is duralumin?
Duralumin is an alloy made from aluminium and copper, which is lightweight yet much stronger than aluminium alone.
128
What is steel?
Steel is an alloy in which iron is mixed with smaller amounts of other metals and carbon, typically having high tensile strength and ductility.
129
Name two alloys that contain copper.
Brass and bronze are two alloys that contain copper.
130
What is solder like?
One type of solder is made from tin and copper, melting at about 227°C, which is lower than the melting points of its components.
131
How are solders used to join copper pipes?
Hot solder flows into the gap between copper pipes and solidifies quickly, allowing an electric current to pass.
132
What are the properties of brass?
Brass is strong, resists corrosion, and is a good conductor of electricity.
133
What are the properties of bronze?
Bronze is stronger and harder than copper, resists corrosion, and is used for making propellers, cymbals, and bells.
134
Why is brass useful for making door knobs?
Brass is strong and resists corrosion, making it ideal for door knobs.
135
Describe the trend in tensile strength and ductility for different carbon steels.
As the carbon percentage increases, tensile strength typically increases while ductility decreases.
136
Why is steel C used for making bridges and buildings?
Steel C has high tensile strength, making it suitable for structural applications.
137
Which steel would be best for making car body panels?
Steel with a lower carbon percentage would be best for making car body panels due to its higher ductility.
138
What is corrosion?
Corrosion is the reaction of a metal with substances in its surroundings such as air and water.
139
What is rusting?
Rusting is a specific type of corrosion that occurs when iron and steel react with oxygen and water.
140
What is the chemical reaction for rusting?
Iron + Oxygen + Water → Hydrated Iron(III) Oxide
## Footnote
This reaction produces the familiar orange-brown rust.
141
What conditions are needed for rusting to occur?
Both oxygen and water are needed for rusting to occur.
142
How can you investigate the substances needed for rusting?
Set up three boiling tubes: one with anhydrous calcium chloride (to keep the nail dry), one with boiled water (no dissolved oxygen), and one exposed to air and water.
143
Why do iron railings rust faster at the seaside?
Iron railings rust faster at the seaside due to the presence of seawater, which increases the rate of rusting.
144
How does silver corrode?
Silver can corrode when it reacts with hydrogen sulfide in the presence of oxygen and water, forming a thin layer of black silver sulfide.
145
What happens to aluminum when it reacts with oxygen?
A microscopically thin layer of aluminum oxide forms on the surface, sealing the metal underneath from further contact with air and water.
146
How is corrosion reduced?
Corrosion is reduced by creating a physical barrier to oxygen and water.
147
What is sacrificial protection?
Sacrificial protection involves a more reactive metal, such as magnesium or zinc, that corrodes first to protect iron or steel.
148
How does sacrificial protection work?
The more reactive metal loses electrons more easily than iron, sacrificing itself to protect the iron or steel.
149
What is galvanising?
Galvanising involves dipping a metal object in molten zinc to create a protective layer that stops air and water from reaching the iron or steel below.
150
What is tin plating?
Tin plating involves electroplating or dipping steel objects in molten tin to protect them from rust.
151
What happens if the tin layer is damaged?
If the tin layer is damaged, the steel acts as a sacrificial metal for the tin and rusts faster.
152
Why is stainless steel more expensive?
Stainless steel contains chromium, which forms an invisible layer of chromium oxide that prevents rust.
153
What are some methods of rust prevention?
Methods include painting, coating with oil, grease, or plastic, and plating with zinc (galvanising) or tin.
154
Why is steel garden wire coated with plastic?
To prevent rusting by creating a barrier against air and water.
155
What is a disadvantage of tin plating?
Tin is less reactive than iron, so if the tin layer is damaged, the steel rusts faster.
156
How does a galvanised steel farm gate prevent rust?
The zinc layer protects the steel from air and water, and acts as a sacrificial metal.
157
Why are magnesium blocks attached to steel legs of oil platforms?
They provide sacrificial protection to prevent corrosion of the steel legs underwater.
158
What are ceramics?
Ceramics are hard, non-metallic materials like brick, china, porcelain, and glass.
159
What properties do ceramics typically have?
High melting points, hard and stiff but brittle, poor conductors of electricity and heat.
160
What is glass made from?
Glass is made by melting sand and allowing it to cool and solidify.
161
What is the structure of glass?
Glass has an irregular giant structure without crystals and is usually transparent.
162
How are other ceramics produced?
They are made by heating clay to very high temperatures, forming tiny crystals joined by glass.
163
What is the purpose of the glaze on china and porcelain?
The glaze forms a smooth, hard, and waterproof surface.
164
What are the requirements for materials used in overhead electrical cables?
They must be good conductors of electricity, lightweight, strong, and resistant to corrosion.
165
Which metal is the best electrical conductor?
Copper is the best electrical conductor among the three metals.
166
Why is aluminium chosen for overhead electricity cables?
Aluminium is a better conductor and less dense than steel, despite not being as strong.
167
What must insulators do?
Insulators must prevent electric currents from passing from the cable to the pylon.
168
What materials are suitable for making insulators?
Poor conductors of electricity, such as ceramics and polymers, are suitable.
169
What are the properties of porcelain as an insulator?
Porcelain has lower resistance than glass and higher compressive strength.
170
Why would glass be suitable for making an insulator where a cable is suspended?
Glass has suitable electrical resistance and can be structurally sound when suspended.
171
Why are steel cables used to carry a lift in a lift shaft?
Steel cables provide the necessary strength to support the weight of the lift.
172
Why is copper used for household cables but not for overhead cables?
Copper has high conductivity but is too heavy and has low tensile strength for overhead use.
173
Why must electrical insulators not contain bubbles or impurities?
Bubbles or impurities can weaken the insulator, making it less effective.
174
Why is poly(propene) used to make ropes and crates?
Poly(propene) is tough and flexible, making it suitable for applications requiring durability.
175
What is a composite material?
A composite material is made from two or more materials combined together, each with different properties. The properties of a composite material are different from those of the materials it contains.
176
What are the properties of composite materials?
Composite materials may be stronger, less dense, or cheaper than their separate components alone.
177
What is cob?
Cob is a traditional building material made from a mixture of clay, sand, straw, and water. It dries to form a strong composite material with properties similar to reinforced concrete.
178
What is the compressive strength of concrete?
Concrete has a high compressive strength, meaning it resists being squashed, making it useful for foundations.
179
What is the tensile strength of concrete?
Concrete has a low tensile strength; concrete beams crack and break if heavy loads are applied.
180
What is steel-reinforced concrete?
Steel-reinforced concrete is a composite material created by embedding steel rods in concrete as it sets, resulting in high compressive and tensile strength.
181
What is fibreglass?
Fibreglass consists of glass fibres embedded in a resin. It is used for canoes, boats, and surfboards.
182
What is carbon fibre?
Carbon fibre consists of carbon fibres in a resin. It is more expensive than fibreglass and is used for sports equipment, racing cars, and aircraft parts.
183
How is concrete made?
Concrete is a composite material that consists of aggregate (small stones), sand, and cement. When water is added, chemical reactions bind the ingredients together.
184
What is plywood?
Plywood is a composite material made by gluing thin sheets of wood together in layers, with the grain in each layer set at right angles to the layer below.
185
What is plasterboard?
Plasterboard is a composite material used for indoor walls, consisting of a thick layer of non-flammable plaster sandwiched between sheets of tough paper.
186
Why is fibreglass considered a composite material?
Fibreglass is considered a composite material because it consists of glass fibres embedded in a resin, combining the properties of both materials.
187
What is the formula for carbon monoxide?
CO
188
What is a life-cycle assessment?
A cradle-to-grave analysis of the impact of making, using, and disposing of a manufactured product.
189
What data should be included in a life-cycle assessment?
Sustainability, environmental impact, lifespan of the product, and disposal.
190
What is one example of data that could be included in a life-cycle assessment?
Waste products.
191
How can life-cycle assessment data be used?
To identify stages that could be improved or alternative materials that might do the same job.
192
What percentage of total energy used in trousers is typically used in production?
20%
193
What is a property of sodium that affects its use in water?
It is less dense than water and reacts violently.
194
What is the maximum usable temperature for poly(propene)?
Above 100°C.
195
Why are polytunnels made from polyethylene rather than PET or poly(propene)?
Polyethylene is suitable for the conditions required for polytunnels.
196
What are two reasons why a life-cycle assessment may be carried out?
To evaluate environmental impact and to improve product sustainability.
197
What conclusion can be drawn from the energy data in Table 2?
Both types of frames use similar amounts of energy.
198
What should you be able to do after studying recycling materials?
Describe how materials or products are recycled for a different use, explain why recycling may be viable, and evaluate factors that affect decisions on recycling.
199
Why is recycling important?
Recycling is important for conserving limited resources, reducing harmful substances in the environment, and reducing waste.
200
What factors affect the decision to recycle a material or product?
Factors include how easily the waste can be collected and sorted, the amount and type of by-products released, the cost of recycling compared to disposal, and the energy involved at each stage.
201
What is waste rock?
Waste rock is left behind after extracting metals from ores.
202
How are materials recycled?
Waste materials must be collected and transported to a recycling plant, where they are sorted and processed.
203
How are metals recycled?
Metals are melted by heating, and the molten metal is poured into moulds to produce new blocks called ingots.
204
How is paper recycled?
Paper is mixed with water, cleaned, then rolled and heated to make new paper.
205
How is glass recycled?
Glass is melted by heating and moulded into new glass objects.
206
How are polymers like PET recycled?
Polymers are melted and formed into new objects.
207
Why are energy savings particularly high for recycling aluminum?
The energy savings are high due to the energy-intensive process of extracting aluminum from its ore.
208
Why is it important to separate PET from other materials before recycling?
It is important to separate PET to prevent contamination during the recycling process.
