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Chemistry GCSE > Topic 8 - Fuels and Earth Science > Flashcards

Topic 8 - Fuels and Earth Science Flashcards

(92 cards)

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1
Q

What is crude oil a main source for?

A

Hydrocarbons

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2
Q

What forms crude oil?

A

Millions of years of high temperature and pressure on buried remains of plants and animals

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3
Q

What type of resource is crude oil?

A

Non-renewable (finite)

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4
Q

How is crude oil seperated?

A

It is heated until most of it has turned into gas and then enters a fractionating column

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5
Q

Describe the relation between hydrocarbon length and boiling point?

A

The longer the hydrocarbon, the higher the boiling point

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6
Q

Give the order of the hydrocarbons released from the fractionating column

A 
Gases
Petrol
Kerosene
Disel
Fuel
Bitumen
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7
Q

What is used for cooking and heating?

A

Gases

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8
Q

What are gases used for?

A

Cooking and heating

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9
Q

What is disel oil used in?

A

Fuel for cars and larger vehicles (eg Trains)

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10
Q

What is fuel oil used for?

A

Fuel for ships and power stations

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11
Q

What is bitumen used for?

A

Surfacing of roads and roofs

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12
Q

What three things must you be able to describe crude oil as?

A

A complex mixture of hydrocarbons containing molecules in which carbon atoms are in chains or rings
An important source of useful substances (fuels and
feedstock for the petrochemical industry)
A finite resource

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13
Q

Explain how crude oil is separated into fractions during fractional distillation?

A

Oil is heated until most of it turns into gas
Gases enter a fractionating column and the liquid part is drained off at the bottom
Since there’s a temperature gradient, the column is hot at the bottom and cooler at the top
The longer HC’s turn back into liquids and drain out lower down the column
Whilst, the shorter HC’s turn into liquids and drain out higher up the column

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14
Q

Explain how crude oil is separated into fractions during fractional distillation?

A

Oil is heated until most of it turns into gas
Gases enter a fractionating column and the liquid part is drained off at the bottom
Since there’s a temperature gradient, the column is hot at the bottom and cooler at the top
The longer HC’s turn back into liquids and drain out lower down the column
Whilst, the shorter HC’s turn into liquids and drain out higher up the column

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15
Q

What does the temperature gradient mean?

A

The column is hotter at the bottom and cooler at the top

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16
Q

What is a homologous series?

A

A family of molecules which have the same general formula and share similar chemical properties

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17
Q

Give examples of a homologous series of hydrocarbons

A

Alkenes

Alkanes

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18
Q

Give an example of a non-hydrocarbon homologous series

A

Alcohol

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19
Q

What is similar among compounds in a homologous series?

A

They have the same general formula
They differ by CH2 in molecular formulae from neighbouring
compounds
They show a gradual variation in physical properties (eg. Boiling point)
They have similar chemical properties

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20
Q

What determines which fraction a hydrocarbon will come out of?

A

It’s length (size)

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21
Q

What physical properties are there to do with hydrocarbons?

A

Ease of ignition
Boiling point
Viscosity

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22
Q

How does length of a hydrocarbon affect the boiling point?

A

The longer the HC, the higher the boiling point

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23
Q

Why does length of a hydrocarbon affect the boiling point?

A

The longer the HC, the stronger the intermolecular forces of attraction meaning the harder they are to break therefore a high temperature is needed

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24
Q

How does length of a hydrocarbon affect the ease of ignition?

A

The longer the HC, the harder to ignite

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25
Why does length of a hydrocarbon affect the ease of ignition?
The shorter the HC, the more likely they are gases meaning they are easier to ignite than liquids
26
Why is it easier for a gas to ignite?
Because it will mix with oxygen in the air to produce a gas mixture which will burst into flames if in contact of a spark
27
How does length of a hydrocarbon affect the viscosity?
The longer the HC, the more viscous the liquid
28
Why does length of a hydrocarbon affect the viscosity?
The longer the HC, the stronger the intermolecular forces meaning harder it is for the liquid to flow
29
What is viscosity?
The measure of how easily a substance flows
30
What do fuels release in combustion reactions?
Energy
31
Why are hydrocarbons great fuels?
Their combustion reactions release alot of energy (very exothermic)
32
What is the complete combustion equation?
Hydrocarbon + Oxygen -> Carbon Dioxide + Water
33
Finish the balanced symbol equation to show the complete combustion of C9H20! C9H20 + _O2 -> _H20 + _CO2
C9H20 + 14O2 -> 10H20 + 9CO2
34
What does complete combustion produce?
Carbon Dioxide and Water
35
What does incomplete combustion produce?
Carbon Dioxide, Carbon Monoxide, Water and Soot
36
Explain why the incomplete combustion of hydrocarbons can | produce carbon and carbon monoxide?
There is less oxygen therefore the products will have much less oxygen
37
Why is carbon monoxide toxic?
Because it can combine with erythrocytes, stopping blood from carrying oxygen And a lack of oxygen in the blood supply to the brain can cause fainting, a coma or even death
38
Why is soot bad?
It can make buildings look dirty, reduce air quality and cause or worsen respiratory problems
39
What other harmful gases do fossil fuels release when burned?
Nitrogen oxides and sulfur dioxide
40
Where does the sulfur dioxide come from in the fossil fuels?
The sulfur impurities
41
What happens to the sulfur dioxide released from combustion?
Some of it will be mix with the clouds to form dilute sulfuric acid which will then fall as acid rain
42
Whats the problems with acid rain?
May cause lakes to become acidic which will kill animals and plants, trees damaged, buildings damaged and metal may corrode
43
When are nitrogen oxides produced?
When nitrogen and oxygen in the air react because of energy released by combustion reactions
44
When are nitrogen oxides commonly produced?
In the internal combustion engines of cars
45
Why are nitrogen oxides harmful?
They can contribute to acid rain and can cause photochemical smog
46
What is photochemical smog?
A type of air pollution that can cause breathing difficulties, headaches and tiredness
47
What are the pros of hydrogen in cars?
Very clean fuel Only product is waste (water) Obtained from a renewable resource (water) Water can be recycled to get hydrogen
48
What are the cons of hydrogen in cars?
Special, expensive engine needed Hydrogen has to be manufactured meaning it will be expensive and will require another external energy source which is most likely non renewable and produces pollutants Hydrogen is hard to store Hydrogen is not widely available
49
Name two pollutants formed by incomplete combustion
Carbon monoxide and soot
50
What is cracking?
The splitting up of long-chain hydrocarbons
51
What does cracking 'convert'?
Long saturated alkane molecules into smaller unsaturated alkene and alkane molecules
52
What is cracking a form of?
Thermal decomposition
53
What is thermal decomposition?
The breaking of one substance into a t least two new ones when you heat it
54
What is often added to help cracking?
A catalyst?
55
Why does cracking involve such high energy (temperatures)?
Because strong covalent bonds must be broken
56
Why are alot of the longer molecules broken up by cracking?
Because: There's more demand for products like petrol and diesel than for bitumen and fuel oil Alkene molecules produced can be used to make polymers
57
Briefly describe how cracking is done?
Vaporised hydrocarbons are passed over powdered catalyst at high temperatures and pressures
58
What is the catalyst used in cracking?
Aluminium oxide
59
Why does the process of cracking require lots of energy?
Because strong covalent bonds must be broken within the alkane molecules
60
When a molecule of C17H36 is cracked, two molecules are made | C5H10 is produced, what is the chemical formula of the other molecule?
17-5=12 36-10=26 C12H26
61
What did volcanoes give out?
Mainly carbon dioxide but some ammonia, steam and methane
62
Describe what the Earth’s early atmosphere was thought to | contain?
Little or no oxygen Large amount of carbon dioxide Water vapour Small amounts of other gases (Methane and Ammonia)
63
What happened to the water vapour?
It condensed to form the oceans
64
What happened to most of the early carbon dioxide?
It dissolved into the oceans
65
What two things caused a rise in nitrogen gas?
Ammonia reacting with oxygen | Denitrifying bacteria
66
What caused the amount of nitrogen to increase and never really decrease?
Nitrogen is very unreactive
67
What caused the rise in oxygen?
The evolution of green plants
68
What did green plants do to the atmosphere?
They photosynthesised releasing oxygen and taking in carbon dioxide
69
What happened to carbon dioxide that wasn't used in photosynthesis or in the oceans?
Locked up in fossil fuels and sedimentary rocks
70
What did the build of oxygen do?
Killed off early organisms that couldn't tolerate it Allowed the evolution of more complex organisms Created the ozone layer which blocked harmful rays from the sun
71
What is the test for oxygen?
A glowing splint relighting
72
Why does an increasing population mean more energy?
There are more that need lighting, heating, cooking, transport, housing and food
73
Why has carbon dioxide in the atmosphere increased over the last 150 years?
The human population has increased rapidly | Lifestyles are changing
74
Why is deforestation bad?
Fewer plants means less carbon dioxide taken out of the atmosphere
75
What does the Sun give out?
Electromagnetic radiation
76
What type of EM radiation are absorbed by the the Earth?
EM waves with short wavelengths
77
What does the absorbed radiation do to the planet?
Heat it up
78
What happens to the absorbed radiation absorbed by the Earth?
Some is radiated which is then either: Asorbed by the greenhouse gases Re-emitted back towards the Earth by the greenhouse gases Re-emitted into space
79
What are greenhouse gases?
Gases in the atmosphere which absorb and reflect heat radiation
80
Give examples of greenhouse gases
Carbon dioxide, water vapour and methane
81
Give two reasons why the increasing human population has affect levels of atmospheric carbon dioxide
Any two from: More land needed so more deforestation, less carbon dioxide absorbed for photosynthesis More people so more carbon dioxide given out by respiration More energy needed for transport/cooking/lighting so more carbon dioxide released from burning of fossil fuels
82
What ways are there to estimate past data?
The analysis of fossils, tree rings or gas bubbles trapped in ice sheets
83
What are the problems of estimating past data?
Much less precise and much less representative of global levels
84
What is global warming?
A type of climate change where the Earth's average temperature has increased
85
Give measures we can take to reduce carbon dioxide emissions
Walk or cycle instead of drive, turn your central heating down or use more renewable energy
86
Name two applications of hydrocarbons?
``` Any two from: Cooking Heating Fuel (Eg. Planes, Trains, Automobiles...) Surfacing of roofs and road ```
87
How is crude oil formed?
Millions of years underground of very high heat and pressure
88
Which elements are HC made from?
Hydrogen and Carbon
89
What is the purpose of fractional distillation?
To seperate the mixtures of hydrocarbons from the crude oil
90
Do longer or shorter HC drain out the bottom?
Longer
91
What types of molecules are produced by cracking?
A smaller alkane and alkene
92
Describe the composition of todays atmosphere
``` 78% Nitrogen 21% Oxygen >1% Carbon Dioxide >1% Noble Gases >1% Water Vapour ```

Chemistry GCSE (9 decks)

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