Topic C6- Global Challenges Flashcards
(99 cards)
1
Q
What is a metal ore?
A
A metal ore is a rock that contains enough metal to make it economically worthwhile extracting the metal from it.
In many cases, the ore is an oxide of the metal.
2
Q
How can metals be extracted?
A
- A metal can be extracted from its ore chemically (through reduction)
- or by electrolysis- which can be used to purify the extracted metal too.
- displacement reactions
- biological methods.
3
Q
How can a metal be extracted using reduction?
A
- A metal can be extracted from its ore chemically by reduction using carbon
- When an ore is reduced, oxygen is removed.
- The position of the metal in the reactivity series determines whether it can be extracted by reduction with carbon
- Metals higher than carbon in the reactivity series have to be extracted using electrolysis.
- Metal below carbon in reactivity series can be extracted by reduction using carbon
- This is because carbon can only take the oxygen away from the metals which are less reactive than carbon.
4
Q
How can metals be extracted using electrolysis?
A
- Metals more reactive than carbon are extracted using electrolysis of molten compounds.
- Once metal is melted, an electric current is passed through it.
- The metal is discharged at the cathode and the non-metal at the anode.
- Electricity is expensive so this process is much more expensive than reduction with carbon.
5
Q
How can electrolysis be used to purify copper?
A
- Copper is easily extracted by reduction with carbon.
- The ore is heated in a furnace- this is called smelting.
- But the copper produced this way is impure
- impure copper doesn’t conduct electricity well
- This isn’t useful because a lot of copper is used to male electrical wiring.
- Electrolysis is used to purify copper, even though it is quite expensive.
- This produces very pure copper, which is a much better conductor.
6
Q
How can you extract metal biologically?
A
- The supply of some metal rich ores is limited.
- The demand for lots of metals is growing and this may lead to shortages in the future.
- Scientists are looking into new ways of extracting metals from low-grade ores.
- or from the waste that is currently produced when metals are extracted.
- examples include: bioleaching and pytoextraction (they use living organisms!)
7
Q
What is bioleaaching?
A
- Uses bacteria to separate metals from their ores
- The bacteria get energy from the bonds between the atoms in the ore
- separating out the metal from the ore in the process.
- The leachate (solution produced by the process) contains metal ions
- which can be extracted by electrolysis or displacement with a more reactive metal.
8
Q
What is phytoextraction?
A
- Involves growing plants in soil that contain metal compounds.
- The plants can’t use or get rid of the metals
- so they gradually build up in the leaves.
- The plants can be harvested, dried and burned in a furnace.
- The ash contains metal compounds
- from which the metal can be extracted by electrolysis or displacement reactions.
9
Q
Give an advantage and disadvantage of biological methods to extract metal from their ores?
A
- These methods of extraction have a much smaller impact on the environment
- It is a very slow process!!
10
Q
What is an alloy?
A
- Alloys can be mixtures of two or more different metals.
- They can also be a mixture of a metal and a non-metal
- Alloys have properties that are different from the metals they’re made from
- these new properties often make the alloy more useful than the pure metal.
11
Q
What is steel an alloy of?
How is steel better than the original metals?
What are some of its uses?
A
- Steel is an alloy of iron and carbon
- Steel is harder than iron
- Steel is stronger than iron, as long the amount of carbon does not get greater than approx. 1%.
- Iron on its own will rust quickly, but steel is less likely to rust.
- examples: girders, bridges, engine parts, cutlery, washing machines, saucepans, ships, drill bits, cars etc
12
Q
What is corrosion?
A
- Process where something is slowly damaged or destroyed by a chemical process.
- Rusting is a type of corrosion.
13
Q
What kind of reaction is the rusting of iron?
A
- It is a redox reaction!
- If iron comes in contact with air and water it will rust.
- rust only happens when iron is in contact with both oxygen and water.
- rust is a form of hydrated iron (III) oxide.
- rusting or iron is a redox reaction. Iron loses electrons when it reacts with oxygen.
- Each Fe atom loses three electrons to become Fe3+, so iron is oxidised.
- Simultaneously, oxygen gains electrons when it reacts with iron.
- Each O atom gains two electrons to become O2-.
- Oxygen is reduced.
14
Q
What is the equation for rust?
A
iron + oxygen –> hydrated iron (III) oxide
15
Q
How can you prevent corrosion?
A
-By coating the metal with a barrier- this keeps out water oxygen or both:
- painting )ideal for large and small structures
- oiling or greasing (used when moving parts are involved)
- tin plating (where tin is applied to the object- acts as a barrier. Only works as long as tin coating remains intact- if tin is scratched to reveal metal below, it will corrode.
- sacrificial method- place a more reactive metal with whatever metal you don’t want to corrode, e.g. galvanising.
16
Q
What is the Haber Process used for?
A
- It is an important industrial process.
- It produces ammonia (NH3), which is used to make fertilisers.
17
Q
What is the equation for the Haber Process?
A
N2(g) + 3H2(g) 2NH3(g) (+heat)
**nitrogen and hydrogen reacts to from ammonia- the reaction is reversible, so ammonia breaks down again into nitrogen and hydrogen. The reaction reaches an equilibrium.
18
Q
Where is hydrogen obtained from in the Haber Process?
A
The hydrogen can be obtained from hydrocarbons from sources such as natural gas or crude oil.
19
Q
What are the reaction conditions in the Haber Process?
A
1) In industry, ammonia is made at a pressure of 200 atm (standard atmosphere) and a temperature of 450ºC in the presence of an iron catalyst.
2) Higher pressures favour the forward reaction (four moles of gas on L-H side, for every 2 moles on the R-H side)
3) So pressure is set as high as possible to give the best yield, without making the plant too expensive to build.
20
Q
In the Haber Process, what kind of reaction is the forward reaction?
A
- It is an exothermic reactions,
- which means that increasing the temperature will move the equilibrium position the wrong way
- away from ammonia and towards nitrogen and hydrogen.
- so the yield of ammonia would be greater at lower temperatures.
- but at lower temperatures, there would be a lower rate of reaction.
- so in industry, the temperature is increased anyway to get a much faster rate of reaction.
- the 450ºC is a compromise between maximum yield and speed of reaction.
21
Q
What happens to the unused hydrogen and nitrogen?
A
It is recycled so nothing is wasted.
22
Q
What does the iron catalyst do in the Haber Process (ammonia reaction)?
A
- The iron catalyst makes the reaction go faster, which gets it to the equilibrium proportions more quickly.
- The iron catalyst doesn’t affect the position of the equilibrium (% yield)
- Without the catalyst, the temperature would be raised even further to get a quick enough reaction,
- that would reduce the & yield even further.
23
Q
What do fertilisers do?
A
-They help plants to grow:
- three main essential elements in fertilisers: nitrogen, phosphorus and potassium.
- Plants absorb these nutrients from the soil.
- if plants don’t get enough of these elements, their growth and life processes are affected.
- fertilises replace the missing elements in the soil, or provide more of them.
- this helps increase the crop yield, as the crops grow faster and bigger.
24
Q
What happens in the Contact Process?
A
1) Make sulfur dioxide (SO2)- burning sulfur in the air.
2) The sulfur dioxide is then oxidised (with the help of the catalyst vanadium pentoxide) to make sulfur trioxide (SO3)
3) Next, sulfur trioxide is used to make sulfuric acid (H2S04)
25
What are the temperature conditions for the Contact Process?
1) Oxidising sulfur dioxide to form sulfur trioxide is exothermic.
2) So to get a higher yield of product, you'd think the temperature should be reduced (so equilibrium will shift to the right to replace heat)
3) But reducing the temperature slows the reaction rate down
4) So a compromise temperature of 450ºC is used- to get an acceptable yield quickly.
26
What are the pressure conditions for the Contact Process?
1) There are two moles of gas on the products side, compared with three moles of gas on the reactants side.
2) So to get a higher yield pf product, you'd think the pressure should be increased (so equilibrium will shift to the right to reduce the pressure
3) But increasing the pressure is expensive (but equilibrium already lies on the right- not necessary)
4) The reaction is carried out at atmospheric pressure.
27
What are the catalyst conditions for the Contact Process/
1) To increase the rate of reaction, a vanadium pentoxide catalyst (V2O5) is used.
2) It doesn't change the position of the equilibrium.
28
What is a life-cycle assessment (LCA)?
-A LCA looks at each stage of the life of a product
- from making the material from natural raw materials,
-making the product from the material,
-using the product and
-disposing the product.
It work out potential environmental impact of each stage.
29
Why should we conserve fossil fuels?
- They are finite resources (will run out eventually)
| - burning them contributes to acid rain and climate change, so it is negatively impacting the environment.
30
What are the benefits of recycling?
- Only uses small fraction of the energy needed to extract and refine the material from scratch.
- energy isn't cheap, so recycling saves money!
- finite amount of raw materials- recycling conserves these resources.
- recycling metal cuts down rubbish getting sent to landfills. (Landfills pollute the surroundings and take up a lot of space.)
31
What are some disadvantages of recycling?
- not an energy-free process. You need energy to reprocess the materials into new forms.
- Items will need sorting out (alloys can be difficult to sort for recycling)
- generally people go for the option that requires them the lowest energy cost (consequences of putting items in a landfill, whether or not the material you are recycling comes from a non-renewable or renewable source.
- you can only recycle materials a finite number of times.
- recycled material is often lower-quality than the original one.
32
What are the different uses of polymers?
- strong, rigid polymers (e.g. high-density polyethene) are used to make water pipes.
- light, stretchy polymers (e.g. low-density polyethene) are used for plastic bags and bottles.
- polystyrene foam is used in packaging to protect breakable things, and as a thermal insulator.
- heat-resistant polymers such as melamine resin and and polypropene are used to make plastic kettles.
33
What is fiberglass?
- consists of fibres of glass embedded in a matrix made of a polymer. (matrix = continuous phase in the composites used to hold the reinforcing agent in its place)
- has a low density but is very strong (like glass).
- fiberglass is used to make skis and boats.
34
What is concrete?
- made from aggregate (sand+gravel) embedded in cement.
- Has a high compressive strength (doesn't break if squashed).
- this makes it ideal for use as a building material (skate parks)
35
What is carbon fibre?
- carbon fibre composites have been made using carbon atoms bonded together to make carbon fibres or carbon nanotubes.
- These are held together in a polymer resin matrix.
- These polymers are expensive to make but are very strong and light making them ideal for used in aerospace and sports car manufacturing.
36
Assess the suitability of polymers for different purposes:
Polymers are:
- really adaptable
- flexible, so are bent without breaking
- easily moulded into almost any shape
- cheaper than most other materials
- they are less dense than most metals and ceramics
- often used for designing products that need low mass
- thermal and electrical insulators
BUT! Polymers can degrade and break down overtime, so polymer products don't always last long as much as ceramics and metals.
37
Assess the suitability of ceramics for different purposes:
Ceramics are:
- insulators of heat and electricity.
- brittle and stiff
- strong and hard wearing
- don't degrade or corrode, so they last longer
38
Assess the suitability of metals for different purposes:
Metals are:
- good conductors of heat and electricity
- malleable, can be formed into a variety of shapes
- some metals corrode easily, but products made of corrosion resistant metals can last for a very long time.
- less brittle than ceramics or polymers
- likely to deform but stay in one piece, while other materials may shatter.
39
Assess the suitability of composites for different purposes:
Composites have:
- different properties depending on the matrix or binder and the reinforcement.
- combination of component materials that can be used to be altered
- can be designed to have specific properties for a specific purpose.
BUT! Main disadvantage of composites is that they tend to be much more expensive to produce than other materials.
40
What are alkanes?
- Alkanes are saturated hydrocarbons.
- They are a homologous series of hydrocarbons- they contain just carbon and hydrogen atoms.
- all atoms in alkanes form bonds with as many other atoms as they can- this means that they are saturated.
- the general formula for alkanes is C n H 2n+2.
- alkanes take part in combustion reactions.
- during a complete combustion reaction, they burn in oxygen to form carbon dioxide and water.
41
What is a homologous series?
A group of chemicals that have similar chemical structures.
42
What are the first eight alkanes called?
```
Methane (CH4)
Ethane (C2H6)
Propane (C3H8)
Butane (C4H10)
Pentane (C5H120
Hexane (C6H14)
Heptane (C7H16)
Octane (C8H18)
```
43
What happens in incomplete combustion?
Incomplete combustion happens in a limited supply of oxygen.
During incomplete combustion, carbon monoxide is produced.
Carbon, in the form of soot, can be given out.
44
What is the equation for the reaction of complete combustion (with ethane as an example)?
Give chemical and word equation.
Ethane + Oxygen --> Carbon Dioxide + Water
| C2H6 + 3and1/2 O2 --> 2CO2 + 3H2O
45
What is the equation for the reaction of incomplete combustion (with ethane as an example)?
Give chemical and word equation.
Ethane + Oxygen --> Carbon Monoxide + Water
| C2H6 + 2and1/2 O2 --> 2CO + 3H2O
46
What are alkenes?
Alkenes are:
- a homologous series of hydrocarbons
- with at least one double bond
- known as unsaturated because they can make more bonds (double bond can open up, allowing two carbon atom to bond with other atoms)
- the general formula for alkenes is C n H 2n.
47
What are the first eight alkenes?
```
Ethene (C2H40
Propene (C3H6)
Butene (C4H8)
Pentene (C5H10)
Hexene (C6H12)
Heptene (C7H14)
Octene (C8H16)
Nonene (C9H18)
```
48
How can you test for alkenes?
You can test for alkenes in bromine water.
- When added to bromine water, an alkene will decolourise the bromine water
- turning it from orange to colourless
- this is because the double bond can open up
- and form bonds with the bromine.
49
What is hydrogenation with alkenes?
In a hydrogenation reaction, two hydrogen atoms are added across the double bond of an alkene, resulting in a saturated alkane.
The hydrogen reacts with the double-bonded carbons.
50
What is the general formula of an alcohol?
C n H 2n+1 OH
51
Which functional group do alcohols contain?
OH- functional group.
52
What are the first four alcohols in the homologous series?
Methanol (CH3OH)
Ethanol (C2H5OH)
Propanol (C3H7OH)
Butanol (C4H9OH)
53
How are carboxylic acids produced?
- Alcohols can be oxidised to form carboxylic acids.
- An oxidising agent, such as potassium magnate (VII), is required.
- They can be formed by oxidising the alcohol which contains the same total number of carbons (i.e. methanol is oxidised to methanoic acid)
54
What are carboxylic acids?
- They are another homologous series of molecules.
- They have the general formula C n-1 H 2n-1 COOH
- They have a COOH functional group.
55
What are the first four carboxylic acids in this homologous series?
```
Methanoic acid (HCOOH)
Ethanoic acid (CH3COOH)
Propanoic acid (C2H5COOH)
Butanoic acid (C3H7COOH)
```
56
What is addition polymerisation?
1) polymers are made by joining lots of small molecules called monomers
2) the monomers that make up addition polymers have a double covalent bond.
3) the monomers with at least one double covalent bond between carbon atoms are called unsaturated compounds
4) molecules with only single bonds between carbon atoms are saturated compounds.
5) lots of unsaturated monomer molecules (alkenes) can open ip their double bonds
6) and join together to form polymer chains
7) this is called addition polymerisation.
57
How can you make addition polymers in a lab?
- alkenes don't just spontaneously polymerise by themselves
- you have to add a chemical called an initiator to get the process going
- once you have added the initiator to the alkene monomers,
- heat the reaction mixture too
- making addition polymers involves flammable chemicals,
- so use a water bath
- to heat reaction vessel.
58
What is condensation polymerisation?
- Involves two different types of monomers
- the monomers react together and bonds form between them, making polymer chains
- Each monomers has to contain at least two functional groups, one on each end of the molecule.
- Each functional group can react with the functional group of another monomer
- creating long chains of alternating monomers.
- for each new bond that forms, a small molecule is lost
59
Give two examples of condensation polymers:
1) Polyesters: form when carboxylic acid monomers and alcohol monomers react together
2) Polyamides: are made from carboxylic acid and amine monomers.
60
How can you make nylon-6,6 in the lab?
1) To make nylon-6,6 mix 1,6-diaminohexane in water in one beaker
2) In a separate beaker, mix 1,6-hexanedioyl dichloride in an organic solvent.
3) Pour one solution on top of the other
4) If you are careful not to mix the solutions, you get two distinct layers.
5) Nylon is formed where these two layers meet.
6) You can extract this layer carefully by slowly lifting it out of the beaker with tweezers and collecting it by wrapping the nylon
7) which forms as a thread, around a rod.
61
Give examples of naturally occurring polymers:
DNA:
1)DNA is a complex molecule that contains genetic information
2)it contains two strands made of nucleotide monomers that bond together in a polymerisation reaction.
3)There are for nucleotide monomers in DNA- adenosine monophosphate (A), guanosine monophosphate (G), cytidine monophosphate (C)
and thymidine monophosphate (T).
Carbohydrates:
1) Carbohydrates are molecules containing carbon, oxygen and hydrogen used by living things to produce energy
2) Starch and cellulose are large, complex carbohydrates which are made of many smaller units of carbohydrates, known as sugars, joined together in a long chain.
62
How is crude oil formed?
- crude oil is formed from the burial remains of plants and animals- it is a fossil fuel.
- over millions of years, with high temperatures and pressure, the remains turn to crude oil, which can be drilled up
63
What is crude oil?
- crude oil is a mixture of lots of different hydrocarbons.
- it is mainly made up of fractions with the general formula C n H 2n+2 - they are alkanes!
- they are our main source of hydrocarbons and is used as raw material
- to create lots of petrochemicals (petrol, natural gas)
64
How can crude oil be seperated?
- Through fractional distillation.
- The oil is heated until most of it has turned into gas.
- The gases enter a fractionating column (liquid part, bitumen, is drained off at the bottom)
- In the column there is a temperature gradient
- hot at the bottom and gradually gets cooler as you go up the column
- the longer hydrocarbons have high boiling points.
- they condense into liquids and drain out of the column at the start when they are near the bottom of the column
- the shorter hydrocarbons have lower boiling points.
- They condense into liquids and drain out much later on, near the top of the column where it is cooler.
65
Name the 7 hydrocarbons that are separated in fractional distillation with the approx. number of carbons.
Name them in order of leaving the column at the bottom to leaving the column at the top:
```
VERY HOT
^ Bitumen (70+)
I Oil (-4)
I Diesel (-20)
I Kerosene (paraffin) (-15)
I Naphtha (-10)
I Petrol (-8)
I LPG)-3
COOL
```
66
What does fractional distillation rely on?
The different hydrocarbons having different boiling points.
67
What are the two important types of bond in crude oil?
- the strong covalent bonds between the atoms within each hydrocarbon molecule.
- the intermolecular forces of attraction between different hydrocarbons molecules in the mixture.
68
What happens in the process of heating crude oil?
- When crude oil is heated, the molecules are supplied with extra energy
- this makes the molecules move about more.
- eventually a molecule might have enough energy to overcome the intermolecular forces that keep it with other molecules
- it now becomes a gas.
- the covalent bonds holding each molecule together are much stronger than the intermolecular forces, so they don't break
- this is why you end up with many small molecules
- the intermolecular forces of attraction break a lot more easily in small molecules
- this is because they are less stronger in small molecules than they are in big molecules.
- this is why big molecules have larger boiling points.
69
What is cracking?
- crude oil fractions from fractional distillation are split into smaller molecules- this is called cracking
- cracking turns long alkane molecules into smaller alkane and alkene molecules.
- it is a form of thermal decomposition, so to break strong covalent bonds, you need lots of heat.
- a catalyst is often added to speed the process up.
- a lot of the longer molecules produced from fractional distillation are cracked into smaller ones
- because their is more demand for products like petrol and diesel than for bitumen or lubricating oil.
- cracking produces lots of alkene molecules, which can be used to make polymers.
70
What is thermal decomposition?
When one substance breaks down into at least two new ones when you heat it.
71
What is the heat, pressure and catalyst in cracking?
1) Vaporised hydrocarbons are passed over the powdered catalyst at about 400ºC-700ºC
2) and 70 atm (pressure)
3) Aluminium oxide is the catalyst used.
- the long chain molecules split apart or 'crack' on the surface of the bits of the catalyst.
72
What are fuel cells?
- An electrical cell that is supplied with a fuel and oxygen
- and uses energy from the reaction between them to produce electrical energy efficiently
- chemical cells produce a potential difference across the cell, until all the reactants have been used up
73
Explain the redox reaction in hydrogen-oxygen fuel cells:
1) The electrolyte is often a solution of phosphoric acid
2) The electrodes are often porous carbon with a catalyst
3) Hydrogen goes into the anode compartment
4) oxygen goes into the cathode compartment
5) the anode is the negative electrode and the cathode is the positive electrode in fuel cells (NOT LIKE ELECTROLYSIS)
6) at the negative electrode, hydrogen loses electrons to produce H+ions = oxidation
7) H+ ions in the electrolyte move to the positive electrode.
8) At the positive electrode, oxygen gains electrons from the electrode and reacts with H+ ions (from electrolyte) to make water
9) This is reduction
10) The electrons flow through an external circuit from the anode to the cathode
11) This is the electric current.
12) The overall reaction is hydrogen plus oxygen, which gives water.
13) There is reduction at the cathode and oxidation at the anode, so the process is a redox reaction.
74
What are the advantages of fuel cells?
1) Hydrogen fuel cells don't generate nasty pollutants when they produce energy.
2) They are also really efficient.
75
What are the disadvantages of fuel cells?
1) It would be really expensive to adapt our current technology to run off fuels cells.
2) Also, hydrogen as a fuel is pretty difficult and expensive to extract and store.
76
What is Phase 1 in the scientific theory of the evolution of the atmosphere?
Phase 1:
1) The Earth's surface was originally molten for many millions of years. There was almost no atmosphere.
2) Eventually the Earth's surface cooled and a thin crust formed, but volcanoes kept erupting, releasing gases from inside the Earth. The gases produced were mainly carbon dioxide, but also steam, methane and ammonia.
3) When things eventually settled down, the early atmosphere was mostly CO2 and water vapour (water vapour condensed to form oceans). There was very little oxygen.
77
What is Phase 2 in the scientific theory of the evolution of the atmosphere?
Phase 2:
1) The previously released CO2 dissolved into the oceans.
2) Nitrogen gas was then put into the atmosphere in two ways- it was formed by ammonia reacting with oxygen, and was released by denitrifying bacteria.
3) N2 isn't very reactive, so amount of N2 in the atmosphere is increased, because it was being made but not broken down.
4) Next, green plants evolved over most of the Earth. As they photosynthesised, they removed CO2 and produced O2.
5) Thanks to the plants the amount of 02 in the air gradually built up and much of the CO2 eventually got locked up in fossil fuels and sedimentary rocks.
78
What is Phase 3 in the scientific theory of the evolution of the atmosphere?
Phase 3:
1) The build up of oxygen in the atmosphere killed off early organisms that couldn't tolerate it.
2) But it did allow the evolution of more complex organisms that made use of the oxygen.
3) The oxygen also created the ozone layer (O3), which blocked harmful rays from the Sun and enabled even more complex organisms to evolve.
4) There is virtually no Co2 left now.
79
What is the composition of the atmosphere?
78% nitrogen
21% oxygen
0.9% argon
0.04% carbon dioxide
80
How does human activity affect the composition of the air?
1) Human population is increasing, more people respiring giving out more carbon dioxide.
2) More people means that more energy is needed for lighting, heating, cooking, transport etc.
3) People's lifestyles are changing: more countries are becoming industrialised and well-off,
- so average energy demand per person is also increasing.
- (More people have electrical gadgets, more people have cars or travel on planes
- increased energy consumption comes mainly from the burning of fossil fuels, which releases more Co2.
4) More people also means more land is needed to build houses and grow food
- (this space is often made by deforestation- plants are the main things taking carbon dioxide out of the atmosphere (photosynthesise),
- so fewer plants means less carbon dioxide is taken out of the atmosphere.
81
What is the greenhouse effect? Explain the process:
- The Sun gives out electromagnetic radiation
- some electromagnetic radiation (at most wavelengths) passes through the atmosphere
- the electromagnetic radiation with short wavelengths is absorbed by the Earth- this warms our planet.
1) Earth radiates some of the heat radiation it absorbs as longer wavelength, infrared radiation (IR)
2) Some of the IR radiation is absorbed by greenhouse gases
3) Some of the IR radiation is re-emitted back towards Earth by the greenhouse gases.
4) Some IR radiation is re-emitted back into space
5) The absorption and re-emission of IR radiation by greenhouse gases is what keeps the Earth warm. It is called the greenhouse effect.
82
What are greenhouse gases?
- Greenhouse gases are the gases in the atmosphere that can absorb and re-emit heat radiation.
- They are only present in small amounts
- Carbon dioxide, water vapour and methane are examples of greenhouse gases.
83
What is global warming?
- There is a scientific consensus that says extra greenhouse gases from human activity (anthropogenic)
- have caused the average temperature of the Earth to increase,
- due to enhanced greenhouse effect.
- this is global warming.
- global warming is a type of climate change and causes other types of climate change (changing rainfall patterns)
- it can cause severe flooding due to polar ice caps melting.
- this can affect the whole world!!!
84
How can we prevent climate change from worsening?
1) Cut down the amount of greenhouse gases WE are releasing into the atmosphere
2) To reduce carbon dioxide emissions , we can limit our own use of fossil fuels. So, walking or cycling instead.
85
Give the pros and cons of ethanol as an alternative fuel:
Pros: produced from plant material, known as biofuel, made by fermentation of plants, sometimes used to power cars, often mixed with petrol to make a better fuel, the CO2 released when burnt was taken in by the plant as it grew making it 'carbon neutral', the only other product is water.
Cons: engines need to be converted before they'll work with ethanol fuels, ethanol fuel isn't widely available, people worry that as demand for ethanol fuel increases farmers will switch from growing crops to growing crops for ethanol- this will increase food prices.
86
Give the pros and cons of biodiesel as an alternative fuel:
Pros: can be produced from vegetable oils e.g. rapeseed oil, can be mixed with ordinary fuel to run a diesel engine, is 'carbon neutral', engines don't need to be converted, produces much less sulfur dioxide and other pollutants.
Cons: we cannot make enough to completely replace diesel, it is expensive to make, it could increase food prices.
87
How is acid rain made + caused?
1) When fossil fuels are burned, they release mostly C02
2) They also release other harmful gases- sulfur dioxide and various nitrogen oxides
3) The sulfur dioxide comes from sulfur impurities in the fossil fuels.
4) The nitrogen oxides are created from a reaction between the nitrogen and oxygen in the air.
5) This is caused by heat of the burning (happens in internal combustion engines of cars)
6) These gases mix with clouds, and form dilute sulfuric acid and dilute nitric acid.
7) This falls as acid rain
Acid rain is mainly caused by powers stations and internal combustion engines.
88
What are the harmful affects of acid rain on the environment?
- acid rain causes lakes to become acidic and many plants and animals die as a result.
- acid rain kills trees and damages limestone buildings
- and ruins stone statues
- this also makes metal corrode.
89
What is photochemical smog?
| What does it cause?
- A type of air pollution caused by sunlight acting on nitrogen oxides
- these oxides combine with oxygen in the air to produce ozone.
- ozone can cause breathing difficulties, headaches and tiredness.
90
What is carbon monoxide gas, and what does it cause?
- Carbon monoxide can sop your blood doing its proper job of carrying oxygen around the body.
- lack of oxygen can lead to fainting, comas, and even death
- carbon monoxide is formed when carbon compounds are burnt without enough oxygen
- this is incomplete combustion
- one way carbon monoxide is produced is by incomplete combustion in petrol or diesel engines.
91
What is particulate carbon?
- During incomplete combustion, small pieces of solids, called particulate, can be released into the atmosphere.
- These are mainly pieces of carbon, called particulate carbon.
92
How do particulates affect the air quality?
- If they escape into the atmosphere, they float around
- eventually they fall back to the ground and deposit themselves as soot.
- they reduce air quality by this and can cause respiratory problems.
93
Where can surface water be found?
Lakes, rivers and reservoirs.
94
Where can groundwater be found?
aquifers (rocks that trap water underground)
| 70% domestic water supply comes from groundwater.
95
Why is it important to conserve water?
- All the water resources are limited
- depend on annual rainfall
- demand for water increases every year
- unless we limit our water use by 2025 we might not have enough water to supply every person's needs
96
Give three ways water can be purified?
1) Filtration- wire mesh screens out large twigs and then gravel and sand beds filter out other solid parts
2) Sedimentation- iron sulfate or aluminium sulfate is added to the water, which makes fine particles clump together and settle at the bottom
3) Chlorination- chlorine gas is bubbled though to kill harmful bacteria and other microbes.
97
Where can nitrate residues come from in tap water?
- Excess fertiliser 'run-off' into rivers and lakes.
- if too many nitrates gets into drinking water, it can cause serious health problems.
- especially for young babies
- nitrates prevent the blood from carrying oxygen properly.
98
Where do lead compounds come from in tap water?
- old lead pipes,
- lead is very poisonous
- particularly in children
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Where can pesticide residues come from in tap water?
from spraying pesticides too near to rivers and lakes.
