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Chemistry > Topic 8 - Fuels and Earth's Sciecne > Flashcards

Topic 8 - Fuels and Earth's Sciecne Flashcards

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1
Q

What are hydrocarbons?

A

Hydrocarbons are compounds that consist only of hydrogen and carbon molecules. Hydrocarbons are alkanes and the carbon atoms will make 4 bonds the hydrogen’s just 1. They are joined through intermolecular bonds. The smaller hydrocarbons have less and smaller intermolecular bonds ( forces)

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2
Q

What is a fuel ?

A

A fuel is something that can be burnt to release heat and light energy. The main examples are: oil, gases, coal and wood ( the first 3 are fossil fuels)

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3
Q

What is crude oil ?

A

Crude oil is unprocessed oil and is a thick black viscous liquid that floats in water. It is a mixture of different sized hydrocarbons. Many hydrocarbons found in crude oil are from a homologous series of chemicals called alkanes.

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4
Q

What is fractional distillation?

A

Fractional distillation is the separation of crude oil into fractions. Fractions of crude oil contain hydrocarbons that have a similar number of hydrocarbons in their chain and have similar boiling points.
The fractions are Gas, petrol, kerosene, diesel, fuel oil, bitumen. “ glamorous people keep dogs for babies”

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5
Q

What is viscosity (a property of fractions)?

A

Viscosity ( physical property )- The thickness of a substance, more viscous is thicker, less viscous is thinner.

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6
Q

What are the stages of fractional distillation work ?

A
  • The fractionating column works because as the crude oil is put into the column it is heated and begins to evaporate.
  • The higher up the column you go the cooler it gets.
  • As the molecules float up the column certain hydrocarbons will be separated into different fractions due to the point at which they boil.
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7
Q

What are the uses of fractional distillation?

A 
Each of the fractions have different qualities and are so therefore sued for different things. 
Gas = bottles gas 
Petrol = fuel of cars 
Kerosene = fuel for aircrafts 
Diesel = fuel for cars, lorries, trains
Fuel oil = fuel for ships 
Bitumen = used for roads and roofs.
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8
Q

What is the general formula for alkanes?

A

CnH2n + 2

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9
Q

What does saturated mean?

A

Saturated means there is a maximum amount of hydrogen atoms.

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10
Q

What are the prefixes and their number of carbons for alkanes?

A 
1 carbon - methane 
2 carbons - ethane 
3 carbons -propane 
4 carbons - butane 
5 carbons - pentane 
6 carbons - hexane
“ monkeys eat pink bananas, pentane, hexane “
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11
Q

What is complete combustion?

A

Compete combustion is when there is enough oxygen for a fuel to burn fully. E.g. methane + oxygen —> carbon dioxide + water

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12
Q

What is carbon monoxide toxic?

A

Carbon monoxide is toxic because it kills in minutes if exposed to, causes dizziness and uncontioustess, it cuts of your oxygen supply stopping respiration and stops oxygen binding in your body.

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13
Q

What are the reactions with acid ?

A 
MASH 
metal + acid —> salt + hydrogen 
BASHO
base + acid —> salt + water 
CASHOCO
carbonate + acid —> salt + water + carbon dioxide.
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14
Q

What is cracking ?

A

Cracking involves the breaking down if larger saturated hydrocarbon molecules ( alkanes ) into smaller, more useful ones, some of which are unsaturated ( alkenes )
-it is a from of thermal decomposition

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15
Q

What are the stages if a laboratory cracking process?

A
  1. Add mineral wool into a test tube
  2. Add liquid paraffin ( the hydrocarbon )
  3. Then add a catalyst e.g. clay
  4. Heat the catalyst and the hydrocarbon
  5. The hydrocarbon will begin to crack and you can collect the gas from the delivery tube.
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16
Q

Why is cracking important?

A
  • Cracking is important because shorter chained hydrocarbons are more desirable and are in demand as they are more useful.
  • there is a smaller supply of them through so it enables us to break larger, less desirable but more common hydrocarbons down.
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17
Q

How is acid rain caused and what are the effects?

A

Acid rain is caused when sulphur dioxide and nitric oxide is release into our atmosphere where it forms with the water vapour I’m out clouds and lowers the PH of our rain.

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18
Q

What was our early atmosphere like?

A
  • earth’s early atmosphere was mainly CO2, water vapour and little or no O2( like the current mars and Venus ). There was probably also methane and ammonia.
  • Gases were produced through volcanic eruptions as steam was produced which cooled, condensed, formed clouds and then rained.
  • Minimal plant life was then formed e.g. algi which began to use up CO2 and produced 02. These are the first steps towards evolving.
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19
Q

What are the percentages of gases in our atmosphere now like?

A

Nitrogen = 78 %
Oxygen = 21%
Nobel gases = 0.97 %
Carbon dioxide = 0.03 %

20
Q

What is the test for oxygen ?

A

Take a glowing splint and place it in a glass jar. If the sample is oxygen it will relight.

21
Q

What is a stromatolite?

A

Stromatolites are 3.7 billion years old and were the first ecosystems to produce oxygen. They are rock formations formed out of layers of Cyanobacteria. They also take part in photosynthesis so carbon dioxide levels decrease and oxygen levels increase.

22
Q

What is the greenhouse effect?

A

The greenhouse effect is the process by which the sun transfers solar radiation to our earth.

23
Q

What are 3 ways scientists can investigate global warming?

A

Ice cores, lab experiments and weather and temperature records.
To create and accurate measure they must take into account all of the tests.

24
Q

What is climate change?

A

Climate change is a long term change in climate in a specific region on earth.

25
Q

What causes climate change?

A

Global warming causes climate change.
That is caused by the production and burning of fossil fuels, intense livestock farming, deforestation, intense rice paddy farming.

26
Q

What are the effects of climate change?

A

Affects of global warming are extinction, destroying habitats, sea levels rising, droughts and extreme weather patterns.

27
Q

What is global warming?

A

global warming is the name given to the process when the earths average temperatures increase due to rising levels of greenhouse gases

28
Q

What are the stages of the greenhouse effect?

A
  • As it reaches the surface some radiation is reflected into to space and some is absorbed.
  • The warm earth then emits energy, some is transmitted into space and some is absorbed by greenhouse gasses in our atmosphere
  • these gases are then re- emitted back onto earths surface resulting in an change in temperature.
29
Q

What are the effects of acid rain?

A
  • Acid rain lowers the PH of our soil and water so kills fish and plants as their wax layer which regulates the amount of water they consume is destroyed.
  • destroys metal and limestone.
30
Q

What are cars installed with to try and reduce the emission of greenhouse gases?

A

Cars are installed with catalytic converters to try and reduce the amount of supper dioxide and nitric oxide released

31
Q

What does fractional distillation leave you with?

A

This then leaves you with separated liquids due to their physical and chemical properties. ( e.g volatility, viscosity, ease of ignition and boiling point )

32
Q

What is volatility (property of factions)?

A

Volatility ( physical property ) - The tendency of a substance to evaporate at room temperature.

33
Q

What is boiling point (property of fractions)?

A

Boiling point ( physical property ) - The temperature at which a substance will evaporate into a gas.

34
Q

What is ease of ignition (property of fraction)?

A

Ease of ignition ( chemical property ) - How easily something catches fire.

35
Q

Why is carbon monoxide dangerous?

A
  • Carbon monoxide is dangerous because is is orderless, colourless, tasteless so you aren’t aware of its presence
  • dense so sinks to the floor and often is released near to where people sleep.
36
Q

What is incomplete combustion?

A

Incomplete combustion is when there isn’t enough oxygen for a fuel to burn fully. It produces : water, carbon monoxide, carbon particulates and energy ( but less then in complete combustion ).
Methane + oxygen —> carbon monoxide + water
Low levels of oxygen means hydrogen and carbon atoms can only be partially broken.

37
Q

What are the fractions?

A 
Bitumen
Fuel oil
Diesel oil 
Kerosene 
Petrol
Gases
38
Q

How does the size of a molecule affect how easily it is broken?

A

The intermolecular forces of attraction break a lot more easily in small molecules than in big ones as their forces are much weaker

39
Q

How does the size of hydrocarbons affect their viscosity?

A

The stringer the force between hydrocarbons the harder it is for the liquid to flow so longer hydrocarbons are more viscous

40
Q

How does size of hydrocarbons affect their ease of ignition?

A

Shorter hydrocarbons are easier to ignite as they have lower boiling points and tend to be gases at room temperature.

41
Q

What do scientists believe about oxygen and why?

A

Scientists believe oxygen was a late addition to our atmosphere as ancient rocks shows iron pyrite and only on the last 2 billion years have their been signs of iron oxide. Oxygen is very reactive and without ongoing photosynthesis, it would be removed through oxidation.

42
Q

What makes a good fuel?

A

Affordable
Clean
Easy to transport

43
Q

What are the advantages of burning fossil fuels?

A
  • reliable
  • affordable
  • easy to transport
  • carries a lot of energy
44
Q

What are the disadvantages of burning fossil fuels?

A
  • nonrenewable

- pollution as it releases carbon dioxide and sulphur dioxide

45
Q

What are some advantages of hydrogen cars?

A
  • clean as the only byproduct is water vapour
  • hydrogen can be extracted through renewable energy resources like hydroelectric energy so good for the environment
  • enhanced aerodynamics
  • they’re quiet
46
Q

What are some disadvantages of hydrogen cars?

A
  • not easy to transport
  • extremely flammable so dangerous if in accident
  • expensive to make the car and to sustain as lots of hydrogen filling stations would have be created

Chemistry (12 decks)

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