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Chemistry > Topic 8: Fuels And Earth And Atmospheric Science > Flashcards

Topic 8: Fuels And Earth And Atmospheric Science Flashcards

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1
Q

What does finite resources mean? Give 4 examples?

A

Resources that are no longer being made or are being made very slowly. E.g Crude oil, natural gas, coal, nuclear power.

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2
Q

What are hydrocarbons?

A

A compound containing only hydrogen and carbon.

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3
Q

What is meant by a homologous series?

A

A family of compounds that have the same general formula and similar properties, but have a different number of carbon atoms.

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4
Q

What is crude oil an example of?

A

A hydrocarbon.

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5
Q

What bonds can the hydrocarbons in crude oil form?

A

Carbon atoms can form 4 covalent bonds, so the carbon atoms in hydrocarbon molecules can join in different ways forming chains and rings.

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6
Q

How do hydrocarbons exists and what does that depend on?

A

hydrocarbons exist in different physical states, depending on the size and complexity of the molecules. Crude oil itself is liquid at room temperature, with hydrocarbons in the solid and gas states mixed with hydrocarbons in the liquid state.

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7
Q

What are the important uses of crude oil:

A
  • fuels for vehicles, aircraft, ships, heating and power stations.
  • feed stock or raw materials for the petrochemical industry.
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8
Q

What is natural gas a mixture of?

A

Hydrocarbons in the gas state. Methane is the main hydrocarbon in natural gas and is used for heating or domestic cooking.

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9
Q

What are non-renewable fossil fuels?

A

These resources are being used up faster than they are being made or replaced and we will one day run out of them.

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10
Q

What are petrochemicals?

A

Substances made from crude oil, such as poly(ethene) and other polymers.

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11
Q

Why can crude oil not be used as fuel?

A

It’s not funny enough or ignite easily enough for it to be useful as a fuel. The different hydrocarbons it contains must be separated into simpler more useful mixtures, through fractional distillation.

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12
Q

Why can fractional distillation be used in crude oil?

A

Because all the different hydrocarbons it consists of have different boiling points.

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13
Q

Where does the industrial fractional distillation happen of crude oil occur?

A

In tall metal fractionating columns.

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14
Q

How is crude oil separated through fractional distillation?

A
  • column is hottest at the bottom and coldest at the top.
  • the vapour rises through the columns and cools down.
  • the vapours condense when they reach part of a column which is cool enough (below their boiling point).
  • the liquid falls into a tray and is piped away.
  • the vapours with the lowest boiling points do not condense at all and leave at the top as a mixture of gases.
  • bitumen has the highest boiling point and leaves at the bottom as a hot liquid.
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15
Q

What different fractions of fuel can you get from crude oil?

A
  • gases
  • petrol
  • kerosene
  • diesel oil
  • fuel oil
  • bitumen
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16
Q

What are the uses of gases from crude oil?

A

Domestic heating and cooking

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17
Q

What are the uses of petrol from crude oil?

A

Fuel for cars

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18
Q

What are the uses of kerosene from crude oil?

A

Fuel for aircrafts

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19
Q

What are the uses of diesel oil from crude oil?

A

Fuel for some cars and trains

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20
Q

M What are the uses of fuel oil from crude oil?

A

Fuel for large ships and power stations

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21
Q

What are the uses of bitumen from crude oil?

A

Surfacing roads and roofs.

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22
Q

Different fractions of crude oil have different uses due to their different properties such as:

A
  • hydrocarbons in gases have the lowest viscosity (flow easily) and are easiest to ignite, making them a suitable use as fuels.
  • bitumen in solid at room temperature, and waterproof making it suitable to surface roads and roofs.

The rest of the hydrocarbon fractions of crude oil are liquid at room temperature.

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23
Q

How easy do the fractions of crude oil boil?

A

Highest boiling point = bitumen

Lowest boiling point = gases

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24
Q

How easily do the fractions of crude oil ignite?

A

Hardest to ignite = bitumen

Easiest to ignite = gases

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25
Q

What is the viscosity of the different fractions of crude oil?

A

Highest viscosity = bitumen

Lowest viscosity = gases

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26
Q

What does viscosity mean?

A

How thick or runny a liquid is. Low viscosity is very runny; high viscosity is very thick.

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27
Q

What are alkanes?

A

A hydrocarbon in which all the bonds between the carbon atoms have a single covalent bond.

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28
Q

What are most of the bonds in the compounds in crude oil fractions made of?

A

Alkanes (single bonds between carbon atoms)

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29
Q

What features do all members of a homologous series have in common?

A
  • the molecular formula of neighbouring compounds differ by CH4.
  • they have the same general formula.
  • they show a trend/gradual variation in physical properties e.g boiling points.
  • they have similar chemical properties.
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30
Q

What is a general formula?

A

A general formula represents the formula for a whole homologous series.

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31
Q

What is the general formula for alkanes?

A

CnH2n+2

The number of hydrogen atoms is twice the number of carbon atoms plus 2.

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32
Q

How is the amount of carbon atoms linked to the boiling point?

A

The larger the amount of carbon atoms in the molecules the higher the boiling point.

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33
Q

Name a chemical property of alkanes?

A

They all react with excess oxygen to produce carbon dioxide and water.

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34
Q

Hydrocarbon fuels react with oxygen in the air. What is this an example of?

A

This is an example of an oxidation reaction called combustion.

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35
Q

What is combustion?

A

A chemical reaction in which a compound reacts with oxygen.

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36
Q

What is the difference between complete and incomplete combustion?

A

Complete combustion: combustion of hydrocarbons with enough oxygen present to covert all the fuel into carbon dioxide and water.

Incomplete combustion: when a substance reacts only partially with oxygen, such as when carbon burns in air producing carbon dioxide, carbon monoxide and carbon soot.

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37
Q

Complete combustion of a hydrocarbon is a reaction in which:

A
  • only carbon dioxide and water are produced.

- energy is given out.

38
Q

Give an example of complete and incomplete combustion:

A

Complete combustion:
When the air whole on a Bunsen burner is open.

Incomplete combustion:
When the air whole in the Bunsen Burner is closes so there is a limited supply oxygen.

39
Q

What is the main hydrocarbon found in natural gas?

A

Methane

40
Q

What are the steps in investigating combustion?

A
  • a pump draws combustion products from the Bunsen burner through the apparatus.
  • iced water cools and condenses water passing through the U-Shaped tube.
  • white anhydrous copper sulphate in the U-shaped tube turns into blue hydrated copper sulphate, showing presence of water.
  • carbon dioxide turns lime water milky in the boiling tube.
41
Q

What happens/produced during the incomplete combustion of a hydrocarbon?

A
  • water is produced.
  • energy is given out (but less than complete combustion)
  • carbon monoxide (CO) and carbon (C) is produced.
42
Q

What sort of problems does complete combustion cause in appliances that use hydrocarbon(such as boilers and heaters)?

A
  • if poorly maintained or unventilated they can cause problems. (E.g. CO leaks)
  • carbon monoxide is a toxic gas which combines with the haemoglobin in red blood cells, preventing oxygen from combining. This reduces amount of oxygen in blood stream causes sleepiness and death in extreme cases.
43
Q

What sort of problems does soot formed from incomplete combustion cause?

A
  • Blocks pipes carrying away waste gases in appliances.
  • Can cause breathing problems if collected in lungs.
  • blackens buildings.
44
Q

What does carbon dioxide form with rain water?

A

Like other soluble non metal oxides it forms an acidic solution.

45
Q

Why is rainwater naturally acidic?

A

Because it contains carbon dioxide from the air.

46
Q

What pH does acid rain usually have?

A

A pH lower than 5.2. Sulphur dioxide is a major cause of extra acidity.

47
Q

What compounds do hydrocarbons contain naturally and how do they occur?

A

Hydrocarbons (such as petrol, diesel oil) contain sulphur compounds. These occur naturally as impurities. However, most of these impurities are removed at oil refineries to to reduce environmental damage.

48
Q

What are some of the problems that are caused by acid rain?

A
  • crops don’t grow well if soil is too acidic (as it’s absorbed the rain)
  • excess acidity in lakes and rivers prevents fish eggs hatching and can kill some insects and fish.
  • it increases weathering in buildings made of limestone and marble and breaks down their structures.
  • also increases rates of erosion in metals e.g iron/steel, weakening them.
49
Q

What is meant by a cars engine is and ‘internal combustion engine’?

A

Fuel is mixed with air and ignited inside the engine. This causes temperatures high enough for nitrogen and oxygen in the air inside the engine to react together. The reactions produce various oxides of nitrogen which are pollutants to our atmosphere.

50
Q

How can nitrogen dioxide cause harm?

A

It is a toxic red-brown gas which can cause respiratory diseases such as, bronchitis.

51
Q

Why do oil refineries use cracking?

A

To match supply to demand. The supply of some fractions of crude oil is greater than customer demand while, the demand for other fractions is greater than the supply.

52
Q

What is cracking?

A

A chemical reaction in which large alkane molecules are broken down into two or more smaller alkanes and alkenes.

53
Q

What is the general formula for an alkene?

A

CnH2n

54
Q

What are hydrocarbons with a carbon double bond (C=C) used to make?

A

Plastic, polymers.

55
Q

What is involved in the process of cracking?

A

Cracking involves breaking covalent bonds in hydrocarbon molecules.

56
Q

What catalyst is used during the process of cracking and why?

A

A catalyst containing aluminium oxide is used. The crude oil vapour is heated to 650°c. This speeds up the reaction that breaks down larger hydrocarbon molecules. Smaller, more useful, hydrocarbon molecules form and these can be used as fuels or for making polymers.

57
Q

Give one difference between alkanes and alkenes:

A

Alkanes are saturated (their carbon atoms are joined by a single bond C-C)

Alkenes are unsaturated (they contain a carbon, carbon double bond C=C)

58
Q

Why is petrol in high demand to be used in fuel for cars?

A
  • It is liquid at room temperature, so large amounts can be stored in cars fuel tank and then pumped into engine.
  • petrol is easily ignited and it’s combustion releases large amounts of energy.
59
Q

How can hydrogen be used as fuel for cars and what are the benefits of using it over petrol?

A
  • its a by product of cracking and can also be produced by reacting methane with steam.
  • unlike petrol it only produces water vapour no carbon dioxide. So hydrogen fuel has environmental benefits as carbon dioxide is a green house gas.
60
Q

What are the disadvantages of using hydrogen over petrol?

A

Like petrol, hydrogen is easily ignited and it’s combustion releases large amounts of energy. Unlike petrol, hydrogen is a gas at room temperature. This makes it difficultly to store in large amounts unless it is compressed under high pressure or liquified by cooling.

61
Q

How can scientists investigate the atmosphere before life evolved?

A

They look at the evidence on Earth and study different planets and moons. These bodies are unlikely to contain life, so their atmospheres may be similar to how earths early atmosphere was.

62
Q

What gases were mostly present in Earths early atmosphere?

A

Mostly carbon dioxide with little water vapour and other gases such as (nitrogen) and very little or no oxygen.

63
Q

How did volcanoes affect Earths early atmosphere?

A

They released large amounts of gases such as carbon dioxide and water vapour and small amounts of other gases including nitrogen. There was lots of volcanic activity in Earths early atmosphere so they probably eloped to form earths atmosphere.

64
Q

How do the atmospheres of Venus and Mars support the idea that Earths early atmosphere contained lots of carbon dioxide?

A

Earth, Venus and Mars are rocky planets with volcanoes. The atmospheres of Venus and Mars are mainly made of carbon dioxide tonight to be released by volcanoes. This supports the idea that Earths early atmosphere contained lots of carbon dioxide.

65
Q

Why do some scientists think Earths early atmosphere could have been mostly nitrogen?

A

Evidence for this theory comes from Titan, a moon that orbits Saturn. Titans atmosphere is 98.4% nitrogen, probably released from volcanoes. However, space probes have showed as Titan has an icy interior, unlike Earth, Venus or Mars. So earths atmosphere is less likely to have been like that.

66
Q

What happened about 4 billion years ago when the Earth started to cool down?

A

Water vapour started to condense to liquid water to form the oceans.

67
Q

What evidence shows there was little or no oxygen in Earths early atmosphere?

A
  • volcanoes do not produce oxygen.
  • iron pyrite is a compound that it broken down by oxygen and so only forms if there is no oxygen and is often found in very ancient rock.
68
Q

What evidence from 2.4 billion years ago suggested that oxygen levels started to rise?

A

Rocks containing bands of iron oxide started to form. The oxidisation if iron suggests that oxygen levels started to rise at this time. There is also fossilised evidence from this time of tiny microorganisms that started to produce oxygen. This oxygen then reacted with iron in the early oceans to produce insoluble iron oxides that formed layers on the sea bed.

69
Q

Over hundreds of millions of years as the oxygen levels increased what happened to the carbon dioxide levels?

A

They decreased.

70
Q

Why do scientists think the formation of oceans on Earth helped reduce carbon dioxide levels?

A

This is one of the hypothesis’ as to why carbon dioxide levels decreased. As water vapour condensed and oceans formed some scientists think carbon dioxide dissolved in the oceans, reducing amount of carbon dioxide in the atmosphere. Sea creatures used the the dissolved CO2 to form shells made of calcium carbonate. This then allowed more CO2 to dissolve in oceans.

71
Q

How did organisms that photosynthesised change Earths early atmosphere?

A

They used sunlight turn carbon dioxide into oxygen.

72
Q

What are Cyanobacteria and what did they form?

A

These are some of the earliest photosynthetic organisms and lived in shallow waters. They grew in huge colonies to produce sticky mucus. The mucus traps a layer of sand and other sediments. The bacteria organisms needed to move through the layer in order to reach sunlight. Over time, the sediment layer build up to form rock shapes called stromatolites.

73
Q

How to stromatolites provide evidence of photosynthetic organisms 3 billion years ago?

A

Some stromatolites are 3 billion years old and provide evidence of photosynthetic organisms as they caused sediment to pile up creating stromatolites. It is thought organisms li,e this caused a rise on oxygen levels in the sea and then the atmosphere.

74
Q

What did Cyanobacteria evolve into and how did this affect the atmosphere?

A

They evolved into other forms of life including plants. When land plants evolved there was another huge spike in oxygen levels as the plants took in carbon dioxide and released oxygen.

75
Q

Why is oxygen important?

A
  • makes up 21% of the atmosphere.
  • important for aerobic respiration in organisms.
  • allows combustion/burning to happen.
76
Q

What is the test for oxygen gas?

A

Pure oxygen relights a glowing splint.

77
Q

How is energy from the sun transferred to Earth?

A

Through light and infrared radiation waves.

78
Q

What does the Earth do with sun ens energy?

A

Earths surface absorbs some of the suns energy, warming it up. The warm earth emits infrared waves. Some gases in the air absorb some of this energy re-emitted. When the gases re-emit this energy some of it is reflected back to Earth. This is called the green house affect and keeps the Earth at a warm level around 14°c without the green house gases Earth would have an average temperature of -18°c.

79
Q

What are the greenhouse gases in our atmosphere?

A
  • carbon dioxide, CO2
  • methane, CH4
  • water vapour, H2O
80
Q

How is human activity affecting the atmosphere?

A

Human activity is increasing the amount of green house gases in our atmosphere, casing global warming. This is then thought to be causing climate change. (Changes to average weather conditions around the world.

81
Q

What is one of the main causes of increased carbon dioxide levels?

A

Burning of fossil fuels, which has occurred since 1850.

82
Q

What is the correlation between rising carbon dioxide levels and Earths average temperature?

A

As carbon dioxide levels rise so does Earths average temperature, creating a strong correlation between these two factors.

83
Q

What evidence so far shows that carbon dioxide levels have caused an average temperature rise?

A
  • scientists can show in the lab that carbon dioxide is absorbs infrared.
  • satellite data confirms ad carbon dioxide levels increase, there has been a reduction in infrared waves from the Earth leaving the atmosphere.
84
Q

How do scientists measure past carbon dioxide levels?

A

Through measuring the concentration of gas trapped in ice cores. The oldest cores come form Antarctica and go back 800,000 years.

85
Q

What equipment do we use today to make temperature readings more accurate compared to the past?

A
  • we use modern thermometers that are less prone to error and have a better resolution.
  • today we can always huge amounts of data from around the world, including temperate measurements from different sources such as, sensors and satellites.
86
Q

Why is methane a more powerful gas than carbon dioxide?

A

Because it is better at absorbing infra red radiation from the Earth.

87
Q

How do humans release methane?

A
  • Methane is the main component of natural gas and is released into the atmosphere when oil and natural gas are extracted from the ground and processed.
  • livestock farming, especially cattle ranching produces a lot of methane. Cattle’s have bacteria in their stomach to digest tough grass. Some of the bacteria produce methane.
  • soil bacteria in land fill sites and in rice ‘paddy’ fields also produce a lot of methane.
88
Q

What are the main causes of the rise of average temperature?

A
  • ice at the South Pole and glaciers to melt.
  • the extra water will rise sea levels and lead to flooding in some areas.
  • high temperatures will result in a loss of ‘sea ice’ at the poles.
  • some animals will move away from their natural habitat to cooler places.
  • some plants and animals will go extinct if they cannot survive in warmer temperatures or find new places to live.
89
Q

What will happen to Earth as weather patterns change due to global warming?

A

-some areas will become drier and others wetter.
-more extreme weather events such as, heavy rainfall, hurricanes, powerful storms and heat waves.
-these changes will affect wildlife and the growth of crops that people depend on.
-

90
Q

How can rising carbon dioxide levels affect the sea and sea life?

A

More carbon dioxide will be absorbed by sea, lowering its pH. This can harm organisms living in the sea, rivers or lakes. Additionally, as ocean temperatures rise, it causes coral to push out the photosynthetic algae that live in their tissue. These algae provide the colour in coral so coral bleaching may occur.

91
Q

How can local people limit the impact of climate change?

A

Other ways if limiting the effects of climate change include helping local people adapt to new conditions. E.g:
Building flood defences, dams and irrigation systems. However, these ideas may destroy habitats and there is a chance they will no work. They also do nothing to limit or reduce carbon dioxide levels in the atmosphere but rather adapt to them.

92
Q

How can humans limit the impact of climate change?

A
  • using renewable energy resources to reduce green house emissions. But this might not be enough to lessen the effects of climate change we are already seeing.
  • global engineering solutions to reflect sunlight back into space or capture CO2 from the air and bury it under ground. However, all countries would need to work together to help reduce emissions and pay for large-scale engineering. There is a risk some counties may not help and some parts of the delicate ecosystems could be destroyed.

Chemistry (14 decks)

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