Global Challenges Flashcards
(184 cards)
1
Q
What is oxidation and reduction in terms of oxygen?
A
oxidation = gaining oxygen
reduction = losing oxygen
2
Q
What is the easiest way to separate a metal from its oxide?
A
react it with carbon to form the metal and carbon dioxide
3
Q
Why can we not use carbon reduction with all metals?
A
you can only use it with metals that are less reactive than carbon
4
Q
What other process separates metals from their oxides other than carbon reduction?
A
electrolysis`
5
Q
Why do we find pure gold in the ground, but not pure iron?
A
gold is too unreactive to react with oxygen in the air, but iron is reactive enough and forms iron oxide
6
Q
What is corrosion?
A
the process by which metals are slowly broken down by reacting with substances from their environment
7
Q
What is the word equation for rusting?
A
iron + oxygen + water —> hydrated iron (lll) oxide
8
Q
what are the conditions required for rusting to take place?
A
water, iron and oxygen
9
Q
What type of reaction is rusting?
A
redox
10
Q
how can we investigate the conditions required for iron to rust?
A
set up 3 test tubes with a bung and an iron nail in each.
The first test tube should have water and no oxygen (water should be boiled to remove oxygen and a layer of oil on top to prevent air dissolving into water)
The second test tube should have just the nail and calcium chloride (to remove any water vapour from the air)
the last test tube should have enough water to keep the nail half way submerged
11
Q
Why doesn’t aluminium break down as it corrodes like iron does?
A
The aluminium oxide forms a protective layer, preventing further oxidation
12
Q
What are the 2 types of methods we can use to protect iron from rusting?
A
barrier methods and sacrificial methods
13
Q
What do barrier methods do?
A
prevent oxygen and water from touching the iron
14
Q
What do sacrificial methods do?
A
a more reactive metal is added to the iron, so that metal reacts instead of the iron
15
Q
what are 3 main barrier methods?
A
paint
oil or grease
electroplating
16
Q
What is electroplating?
A
using electrolysis to cover the iron with a thin layer of another metal
17
Q
What is an example of protection that uses both barrier and sacrificial methods?
A
galvanising
18
Q
What is galvanising?
A
coating an object in a thin layer of zinc
19
Q
What is the Haber process?
A
the industrial production of ammonia from nitrogen and hydrogen
20
Q
What is the ammonia used for in the Haber process?
A
to create nitrogen based fertilisers
21
Q
How does the Haber process work?
A
1) input the nitrogen and hydrogen into the reacting vessel
2) Some of the nitrogen and hydrogen react to form ammonia
3) The mixture passes into the condenser and the ammonia cools down to liquid ammonia (it has a higher boiling point) whilst the hydrogen and nitrogen stay gaseous
4) the liquid ammonia is collected and the nitrogen and hydrogen are recycled
22
Q
What are the conditions inside the reacting vessel in the haber process?
A
450 C
200 atm
iron catalyst
23
Q
Why does the Haber process take place at 450 C and 200 atm?
A
as the reaction exothermic, a lower temp. favours the forward reaction and higher % yield, but to achieve a higher rate of reaction, more temp is needed. 450 C is selected as a compromise. A higher temperature is too expensive as well
Higher pressure will increase rate of reaction and push equilibrium to the right, increasing % yield. High pressure is very expensive and can be dangerous, so 200 atm is a compromise
24
Q
Is the Haber process an exothermic or endothermic reaction?
A
exothermic
25
Which metal acts as a catalyst for the Haber process?
iron
26
Where do we get the nitrogen required for the Haber process from?
take it from the air
27
Where do we get the hydrogen required for the Haber process from?
make it from hydrocarbons
28
What is a fertiliser?
a substance that is applied to soil, in order to supply plants with nutrients.
29
What is a formulation?
a mixture that has been designed as a useful product. e.g. paint, fertiliser etc.
30
What does NPK stand for in NPK fertilisers?
nitrogen (N), phosphorous (P), potassium (K)
31
What are the 3 main elements that plant need from soils?
nitrogen, phosphorous and potassium
32
What is used to provide nitrogen in the fertilisers?
ammonia made from the Haber process
33
What is the contact process?
the industrial process which produces sulphuric acid
34
What are the 3 main steps in the contact process?
1) sulphur is combusted with oxygen to form sulphur dioxide
2) Sulphur is further oxidised using vanadium (V) oxide catalyst to form sulphur trioxide
3) the sulphur trioxide is reacted with water to sulphuric acid
35
What are the 3 main steps in the contact process using equations?
1) S + O₂ → SO₂
2) 2SO₂ + O₂ ⇄ 2SO₃
3) SO₃ + H₂O → H₂SO₄
36
What are the optimal conditions for the contact process?
450 C
2 atm
vanadium (V) oxide catalyst
37
Which factor increases the rate of reaction but decreases the percentage yield in the contact process?
temperature
38
What is the purpose of a life cycle assessment (LCA)?
To assess the environmental impact of products
39
What are the stages of a LCA?
extracting and processing the raw materials
manufacturing and packaging the product
using the product
disposing of the product
40
What are 3 limitations of LCAs?
Companies can manipulate their LCAs to look more favourable
It is difficult to gather all of the required data about each step
It is difficult to compare different harms e.g. lung disease vs global warming
41
What are some of the characteristics of ceramics?
hard, brittle, heat-resistant, corrosion-resistant
42
How are ceramics made?
by shaping and then firing a nonmetallic material, such as clay, at a high temperature.
43
what are the 2 main groups of ceramics?
clay ceramics and glass.
44
What are 3 clay ceramics and what is a characteristic they share?
brick, china, porcelain
high compressive strength
45
What is the most common glass we use?
soda-lime glass
46
what is a difference in soda-lime glass and borosilicate glass?
borosilicate glass has a much higher melting point
47
What are composites?
A composite material consists of two or more materials with different properties, that have been combined to produce a material with more desirable properties.
48
What are the 2 components most composite materials are made from?
the reinforcement (long solid fibres or fragments)
the matrix (binds the reinforcements together, often starts soft then hardens)
49
What are polymers?
large molecules of high relative molecular mass and are made by linking together large numbers of smaller molecules called monomers.
50
Generally, what properties do polymers have?
flexible, easily shaped, and good insulators of heat and electricity.
51
What does LDPE stand for?
low-density poly(ethene)
52
Which type of poly(ethene) is most flexible, but weakest?
LDPE
53
What does HDPE stand for?
high-density poly(ethene)
54
Which type of polymers melt easily when heated?
Thermosoftening polymers
55
What are the 2 types of polymers?
Thermosoftening polymers
thermosetting polymers
56
What are general characteristics of metals?
malleable, ductile, good conductors of heat and electricity, and have high melting and boiling points
57
What is the key difference between metals and alloys?
Alloys are not malleable and much stronger
58
how does fractional distillation work?
Crude oil is a mixture of hydrocarbons with different boiling points.
The first step is to heat the crude oil to a very high temperature so that all of the compounds are evaporated from liquid to gas.
The hot gaseous hydrocarbons then rise up the fractionating column (because hot gas rises).
As they rise, they cool down, because the top of the column is cooler than the bottom.
The hydrocarbons will condense when they become cooler than their boiling point, and the liquid hydrocarbons then collect in trays and drain out.
The longer chain hydrocarbons condense at the bottom of the fractionating column because they have high boiling points.
Meanwhile the shorter chain hydrocarbons condense at the top of the column because they have much lower boiling points.
59
What 3 hydrocarbons are used as fuels?
Diesel
Petrol
Kerosene
60
What is a petrochemical?
a substance made from crude oil via chemical reactions.
61
what is feedstock?
a raw material used to provide reactants for an industrial reaction.
62
What are alkanes?
a homologous series of molecules that are hydrocarbons and that only have single bonds
63
What is the general formula for alkanes?
CnH2n+2
64
What does a homologous series mean?
group of organic compounds that have similar chemical properties, due to them having the same general formula.
65
What does saturated and unsaturated mean in terms of molecular bonds?
saturated means that only single bonds are present, but unsaturated means that other bonds are also present (e.g. double bonds)
66
What is the general formula for alkenes?
CnH2n
67
What is a fuel cell?
a type of electrochemical cell that converts energy between chemical and electrical
68
In hydrogen fuel cells, which electrode has what charge?
anode - negative
cathode - positive
69
What are the electrodes made of in fuel cells?
porous carbon with catalyst
70
How do hydrogen fuel cells work?
1) Hydrogen comes into the anode compartment and gets oxidised by the anode to become H+ ions
2) the electrons pass around the wire to the cathode, whilst the hydrogen ions pass through the electrolyte to the cathode
3) the hydrogen ions, electrons and oxygen (from the cathode compartment, react together to form water.
4) the water leaves the fuel cell through the outlet
71
What is the reaction happening at the anode in a hydrogen fuel cell?
H2 ----> 2H+ + 2e-
72
What is the reaction happening at the cathode in a hydrogen fuel cell?
O2 + 4H + 4e- -----> 2H2O
73
What is the overall reaction in a fuel cell?
O2 + 2H2 ----> 2H2O
74
What generates electricity in a hydrogen fuel cell?
the oxidised hydrogen atoms, create a potential difference across the electrodes, driving the electrons through the wire to the cathode
75
What are 3 pros of hydrogen fuel cells?
only require hydrogen and oxygen (abundant)
dont produce waste
relatively simple
last longer than batteries
less polluting to dispose of
76
What 4 properties change as a hydrocarbon gets longer?
longer hydrocarbons:
have higher boiling points
are less volatile
are more viscous
are less flammable
77
What products does complete combustion form?
carbon dioxide + water
78
What products does incomplete combustion form?
carbon monoxide + (soot) + water
79
During a combustion reaction, are carbon and hydrogen oxidised or reduced?
oxidised
80
What functional group do alcohols have?
OH
81
What is the general formula for alcohols?
Cn H2n+1 OH
82
What are the 3 main properties of alcohols?
flammable
soluble
can be oxidised to make carboxylic acids
83
What are some uses of alcohols?
fuels
solvent (they can dissolve things water can't)
84
What is the pH of alcohols?
7
85
What is the functional group of carboxylic acids?
COOH
86
What does propanoic acid ionise into?
propanoate negative ion and hydrogen positive ion
87
What are the products when ethanoic acid is ionised?
CH3COO- + H+
ethanoate ion + hydrogen ion
88
What is ethanoic acid + potassium carbonate?
potassium ethanoate + water + carbon dioxide
89
How are carboxylic acids made?
by oxidising an alcohol
90
What does it mean if carboxylic acids are weak acids?
weak acids do not fully ionise in water. This means that weak acids don't release all their
hydrogen ions.
91
What is the general formula of carboxylic acids?
Cn H2n+1 COOH
92
What is addition polymerisation?
adding multiple monomers together to form a long chain polymer
93
What conditions are needed for addition polymerisation?
high pressure and catalyst
94
What type of molecules are used in addition polymerisation?
alkenes
95
What is an ester link?
carbon bonded to 2 oxygens, with one being a double bond. These are created during condensation polymerisation
96
What are 2 things that reactants must have to undergo condensation polymerisation?
each monomer must have 2 functional groups
there should be 2 different functional groups overall.
Usually a dicarboxylic acid + a diol
97
What is a dimer?
two monomers combined
98
Which type of polymers are biodegradeable?
condensation polymers
99
Why are condensation polymers biodegradable?
Ester links can be broken down by microorganisms
100
What are 3 naturally occurring polymers?
polypeptide, DNA, Carbohydrates
101
What are polypeptides made up of and what do they make when folded up?
amino acids, proteins
102
What is DNA made up of?
nucleotides
103
What are carbohydrates made up of?
Sugars
104
What functional groups do amino acids contain?
amino group
carboxylic acid group
an 'R' group
105
what is an amide or peptide bond?
carbon double bond to oxygen and single bond to nitrogen
106
What are the three elements that make up carbohydrates?
Carbon
Hydrogen
Oxygen
107
What is cracking?
breaking of longer chain hydrocarbons into shorter chains
108
What are the 2 types of cracking?
steam and catalytic
109
How does catalytic cracking work?
the longer chain hydrocarbons are heated and vapourised
the vapour is then passed over hot powdered aluminium oxide (catalyst)
this causes the hydrocarbon to break into smaller hydrocarbons
110
How does steam cracking work?
The longer chain hydrocarbons are heated and vapourised
the vapour is mixed with steam and heated to very high temperatures
this causes the long chain hydrocarbon to split into smaller ones
111
What two types of products does cracking create?
shorter alkane and alkene
112
What type of reaction is cracking?
Thermal decomposition reaction
113
How do you distinguish between alkanes and alkenes?
if you add alkene to bromine water, it will change colour from orange to colourless
114
What are the approx. percentages of gases in our atmosphere?
78% nitrogen
20% oxygen
1% argon
0.04% carbon dioxide
115
What was the earth's atmosphere like in the first billion years?
very dry
intense volcanic activity
lots of co2 (most), water vapour and nitrogen
some methane and ammonia
116
What happened to initially cause carbon dioxide to decrease in atmosphere?
water vapour condensed into water and co2 dissolved into the water
117
What happened to atmosphere after CO2 dissolved into water?
algae and plants arrived and their photosynthesis decreased amounts of carbon dioxide in the air and increased oxygen levels
118
roughly how old is the Earth?
around 4.6 billion years old
119
What happened in the water when carbon dioxide dissolved into it?
carbonates were precipitated, creating sediments
120
What are 3 greenhouse gases?
water vapour
carbon dioxide
methane
121
what is the greenhouse effect?
solar radiation hits the earth in short wave radiation
some it reflected, some is absorbed and re-emitted
some energy makes it back to space but most is absorbed by greenhouse gases in atmosphere
these molecules re-emit the energy and the process of absorption and emission happens over and over again.
this keeps energy trapped near earth, keeping temps warmer and more stable
122
what are the 2 main reasons for CO2 increase in atmosphere?
deforestation and burning of fossil fuels
123
What are the 2 main reasons methane levels are increasing?
farm animals produce methane during digestion
huge amounts of waste may release methane as it decomposes
124
What are some of the consequences of climate change?
rare weather events (flood, droughts etc.) will become more common and severe
sea level rise
species may not be able to survive in different environment
125
What are the products of the complete combustion of a hydrocarbon?
water + carbon dioxide
126
What are the products of the incomplete combustion of hydrocarbons?
carbon monoxide + soot + water
127
What problems can soot cause?
respiratory problems
global dimming due to smog - more light reflected back into space
128
What is a problem with carbon monoxide?
Carbon monoxide can bind to red blood cells instead of oxygen and doesn't unbind meaning less oxygen is able to travel to cells around the body. This can cause fainting, coma, death.
129
Why is carbon monoxide particularly hard to detect?
it is colourless and odourless
130
How is sulphur dioxide created?
some hydrocarbons have impurities in them like sulphur, which is oxidised to form sulphur dioxide when hydrocarbons are combusted.
131
How are nitrogen oxides created?
when nitrogen reacts with oxygen in the air.
But this doesn't usually happen as it requires very high temperatures.
132
Where do most nitrogen oxides form and why?
inside internal combustion engines, such as car engines, as nitrogen and oxygen need high temperatures to react.
133
What are the 2 problems with sulphur dioxide and nitrogen oxides?
1) they can cause respiratory problems
2) they can dissolve in clouds to form dilute sulphuric or nitric acid which then falls as acid rain, damaging infrastructure and plants.
134
What are 3 types of waste water?
domestic
agricultural
industrial
135
What is domestic waste?
household waste like water from shower, sinks and toilets.
136
What is agricultural waste?
nutrient run-off from fields and animal waste
137
What is industrial waste?
waste from factories that make and use chemicals and water
138
What are the 3 main steps in sewage treatment?
1) screening - removing large objects like plastic and sticks
2) let sewage sit in settlement tank and let sedimentation take place (sludge forms at bottom and effluent forms at top
3) Biological breakdown by microorganisms
139
What is sludge and effluent?
sludge is heavier solid bits that have sunk to the bottom
effluent is the light part above the sludge
140
What is the key difference between the effluent and sludge tanks?
sludge is anaerobic
effluent is aerobic
141
Why is the sludge broken down in anaerobic conditions?
product of breakdown is methane which can be burnt and fertiliser
142
What happens once both sludge and effluent have been broken down?
sludge products are methane which is burnt and fertiliser which is used/sold
effluent product is clean, safe water which is reused
143
How are possible toxic substances removed from the waste water?
by adding chemicals or using UV radiation
144
How is the effluent tank given aerobic conditions and the sludge tank anaerobic conditions?
effluent tank has air pumped into it
sludge tank is sealed
145
What are 2 ways fuel cells can cause pollution?
1) fossil fuels may be used in manufacturing process
2) catalyst is poisonous so when disposing may pollute environment
146
What are symptoms of nitrogen deficiency in plants?
poor growth
yellow leaves
147
What are symptoms of phosphorus deficiency in plants?
poor root growth
discoloured leaves
148
What are symptoms of potassium deficiency in plants?
poor fruit growth
discoloured leaves
149
What are the 4 compounds for fertilisers made in fertiliser factories?
ammonium nitrate
ammonium sulphate
ammonium phosphate
potassium nitrate
150
What are the differences between making fertilisers in the lab and industrially?
industrially is continuous process, whereas lab is batch process, so they make more and go on all the time
in a lab you use pure substances but industrially you start with raw materials and have to purify them
151
In which ores are copper carbonate, aluminium oxide and iron (III) oxide found?
malachite
bauxite
haematite
respectively
152
What is an ore?
a rock or mineral that contains enough metal or metal compound to make it economical to extract the metal
153
How is iron extracted from its ore?
using a blast furnace
154
What is added to the blast furnace?
from the top:
iron ore
coke (mostly carbon)
limestone - to purify the iron
from the bottom:
hot air
155
What reactions happen in a blast furnace?
coke burns in the hot air, making carbon dioxide
more coke reduces the carbon dioxide into carbon monoxide
carbon monoxide reduces iron (III) oxide to iron and carbon dioxide
156
How does the limestone purify the iron?
calcium carbonate (limestone) decomposes in the high temperatures into calcium oxide and carbon dioxide
the calcium oxide produced reacts with silica from the sandy impurities in the iron to form calcium silicate
157
What is slag?
the molten calcium silicate that floats on top of the molten iron
158
What is a problem when electrolysing aluminium oxide and how is it overcome?
its melting point is too high (over 2000) so it would be too expensive to heat it up to that temperature
aluminium oxide is dissolved in molten cryolite which lowers the melting point (to about 950)
159
How does bioleaching work?
uses bacteria to extract metals from low-grade ores by converting them into a soluble form, producing a leachate containing metal ions. These metal ions can then be extracted using methods like electrolysis or displacement reactions
160
What are the benefits of bioleaching?
cheaper
allows metals to be extracted from low-grade ores
bacteria occur naturally
does not release harmful gases into the atmosphere
161
What are the drawbacks of bioleaching?
slow
toxic substances can sometimes be formed
care must be taken to avoid these and sulphuric acid escaping into water supplies and the soil
162
How does phytoextraction work?
a crop is planted in soil containing low-grade ore or mine waste
the plants are then harvested, then burnt to produce an ash with a high concentration of the metal
the metal can then be extracted as if the ash were a high-grade ore
163
What can be added to help the plants absorb more mineral ions in phytoextraction?
a complexing agent
164
What are the benefits of phytoextraction?
cheaper
produces less waste
close to being carbon-neutral
165
What are drawbacks of phytoextraction?
slow
crops may need replanting and harvesting for several years before the available metal is removed from the soil
166
What are 5 alloys and what are they made up of?
steel - iron and carbon
duralumin - aluminium and copper
solder - tin and lead
brass - copper and zinc
bronze - copper and tin
167
What are uses of steel, duralumin and solder?
steel - buildings, bridges cars
duralumin - aircraft parts
solder - joining electrical components and copper pipes
168
What are uses for brass and bronze?
brass - musical instruments and coins
bronze - bells, propellers for ships
169
What important trait do both brass and bronze share?
they are resistant to corrosion
170
What are the 2 main types of condensation polymers?
polyesters
polyamides
171
What are polyesters?
have many ester groups (-COO-)
made from a carboxylic acid with 2 carboxyl groups and an alcohol with 2 hydroxyl groups
172
What are polyesters used for?
clothing and fizzy drinks bottles
173
What are polyamides?
made from a carboxylic acid with 2 carboxyl groups and an amine with 2 amino groups
contain many amide groups (-CONH-)
174
What are polyamides used for?
nylon to make clothing and carpets
175
What is the amino group?
-NH2
176
How is ammonia used to make nitric acid?
reacted with oxygen and water in a series of reactions
177
How is ammonia used to make ammonium salts?
reacted with acids
178
How is phosphorus fertiliser produced?
phosphate mined from the ground as phosphate rock
phosphate rocks reacted with acids to produce soluble salts to be used as fertilisers
179
What does the reaction between nitric acid and phosphoric rocks produce?
phosphoric acid and calcium nitrate
180
What does the reaction between sulphuric acid and phosphoric rocks produce?
a mixture called single superphosphate
181
What does the reaction between phosphoric acid and phosphoric rocks produce?
calcium phosphate also known as triple superphosphate
182
What are the products when hydrocarbons are completely combusted?
carbon dioxide
water
183
What are the products when hydrocarbons are incompletely combusted?
carbon monoxide and/or soot
water
184
