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Chemistry > 1.4 + 1.5 Crude Oils And Fuel > Flashcards

1.4 + 1.5 Crude Oils And Fuel Flashcards

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1
Q

What is crude oil a mixture of?

A

Carbon compounds

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2
Q

How is crude oil formed?

A

Over millions of years from the remains of tiny sea creatures

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3
Q

Organic chemistry

A

The study of carbon compounds- called this as many if these compounds are made from living things.

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4
Q

Hydrocarbon

A

Simplest type of organic compound- compounds containing hydrogen and carbon only.

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5
Q

Alkanes

A

Saturated hydrocarbons- contain maximum amount of hydrogen possible in each molecule.
Useful fuels as they release lots of energy when they burn.

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6
Q

Naming alkanes and alkenes first 5?

A 
Meth-
Eth-
Prop-
But-
Pent-
(Monkey Eat Peanut Butter Pancakes)
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7
Q

Alkane formula?

A

CnH(2n+2)

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8
Q

Properties of alkanes?

A

👉 As the chain length increases(increasing number of carbons in the chain) ;
✖️the boiling point also increases
✖️ the alkanes get more viscous
✖️ the smokiness of the flame increases
✖️ the harder it is to light the alkanes
✖️ the appearance become darker.

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9
Q

Fractional distillation process

A
  1. Heat the crude oil~ 400 degrees celsius
  2. High B.P (>400 degrees celsius) molecules stay as liquid and are collected.
  3. Vapour rises up the column until it gets cool enough to collect.
  4. Molecules with different boiling points condense at different levels👉 separating them into fractions.
  5. Molecules with very low b.p stay as a gas and come out at the top of the column..
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10
Q

What is crude oil?

A

A mixture of hydrocarbon

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11
Q

What is the meaning of the term ‘fraction’?

A

To separate different groups of hydrocarbons

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12
Q

What property is used to separate the fractions?

A

Boiling points

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13
Q

Order of fractions👉 low boiling point to high boiling point?

A 
Petroleum gas(LPG)- calor/camping gas
Petrol(gasoline)- petrol
Kerosine(paraffin)-aviation
Diesel(gas oil)-central heating
Heavy oil(lubricating)-lubrication oil
Bitumen(tar)- road surfaces, roofs
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14
Q

When testing the products of combustion, what gas in the air is needed for combustion to occur?

A

Oxygen

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15
Q

When testing the products of combustion, why is the funnel upside down above the bunsen burner?

A

To collect gases

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16
Q

When testing the products of combustion, what is the purpose of the water pump?

A

It sucks the gases through the apparatus.

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17
Q

When testing the products of combustion, why is the U-tube surrounded by ice?

A

To cool it down so the water condenses.

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18
Q

When testing the products of combustion, what gas does limewater test for?

A

Carbon dioxide

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19
Q

When testing the products of combustion, what does the cobalt chloride test for?

A

Water- turns blue paper pink.

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20
Q

Show the combustion of the alkane, methane?

A

Methane + oxygen 👉 carbon dioxide + water

CH4 + 2O2 👉 CO2 + 2H2O

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21
Q

During complete combustion the hydrogen in the alkane…

A

Combines with the oxygen to form water.

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22
Q

During complete combustion the carbon in the alkane…

A

Combines with oxygen to form carbon dioxide

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23
Q

What have the carbon and hydrogen both been

, when they have fully combusted?

A

Oxidised

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24
Q

When does complete combustion occur?

A

When an alkane burns in a plentiful supply of oxygen

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25
Q

When does incomplete combustion occur?

A

If the amount of oxygen is restricted.

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26
Q

Why does incomplete combustion happen?

A

Because there always has to be enough oxygen to form water from the Hydrogen in the alkane, but if there is not enough oxygen then some carbon monoxide or carbon is formed instead of carbon dioxide.

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27
Q

What is the chemical equation of the incomplete combustion of two molecules of methane?

A

2CH4 + 2.5O2 👉 CO + C + 4H2O

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28
Q

Why should incomplete combustion be avoided?

A

It gives off less heat/ the energy and carbon monoxide is poisonous/toxic.

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29
Q

Impurities in fuel can also…

A

Burn in oxygen.

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30
Q

What is often found in fossil fuels such as crude oil?

A

Sulfur
E.g
Sulfur + oxygen 👉 nitrogen oxide

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31
Q

Is nitrogen in fuel?

A

No, it is not an impurity in fuel, but makes up about 79% of the air.

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32
Q

What happens if nitrogen is heated to high temperatures(such as those found in engines?

A

The nitrogen can combine with the oxygen to form nitrogen oxides.
P.s nitrogen forms many different oxides with different formulae so nitrogen oxides are often referred to as NOx
So nitrogen + oxygen 👉 nitrogen oxide

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33
Q

What two gases are acidic and lead to acid rain?

A

Sulfur dioxide

Nitrogen oxides

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34
Q

What are the 5 pollutants caused by burning fossil fuels?

A 
Carbon dioxide
Carbon monoxide
Sulfur dioxide
Nitrogen oxides
Particulates ( carbon soot and unburned hydrocarbons.)
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35
Q

How is CO2 produced?

A

When a fuel containing carbon is burned e.g hydrocarbons in fossil fuels

36
Q

How is carbon monoxide produced?

A

By incomplete combustion of hydrocarbons

37
Q

How is sulfur dioxide produced?

A

When a fuel containing sulfur impurities are burned e.g fossil fuels

38
Q

How is nitrogen oxide produced?

A

Oxygen and nitrogen combine at high temperatures e.g in car engines

39
Q

How are particulates produced?

A

Incomplete combustion of hydrocarbons.

40
Q

Problems caused by CO2?

A

Green house effect- leads to global warming, climate change (NOT HARMFUL TO HEALTH!!)

41
Q

Problems caused by carbon monoxide?

A

HARMFUL TO HEALTH!

Toxic- stops red blood cells from carrying blood.

42
Q

Problems caused by sulfur dioxide?

A

Acid rain, engine corrosion.

HARMFUL TO HEALTH- causes asthma

43
Q

Problem caused by nitrogen oxide?

A

Acid rain, smog.

HARMFUL TO HEALTH- causes asthma.

44
Q

Problems caused by particulates?

A

Global dimming, smog.

HARMFUL TO HEALTH- causes asthma and linked to cancer

45
Q

Solutions for carbon dioxide?

A

Save energy

Burn less fossil fuels

46
Q

Solutions for carbon monoxide?

A

Ensure there is a good supply of oxygen (fresh air) when fuel is burned.
Catalytic converters on cars.

47
Q

Solutions for sulfur dioxide?

A

Burn less fossil fuels.

Remove sulfur dioxide from emissions- neutralise the acidic gas with a base e.g calcium oxide

48
Q

Solutions for nitrogen oxides?

A

Catalytic converters on cars.

49
Q

Solutions for particulates?

A

Burn less fossil fuels
Use cleaner burning fuels
Ensure enough oxygen when fuel is burned

50
Q

Why is important to say ‘known reserves’ if talking about oil or something?

A

As there might be some which we do not know about.

51
Q

What else is crude oil used for apart from fuels?

A

Plastics

52
Q

Fuel

A

A substance that can be burned to release energy

53
Q

Types of Fossil fuels?

A

Coal, oil and natural gas

54
Q

What are fossil fuels mostly made up of?

A

Hydrocarbons

55
Q

Where does the energy stored in fossil fuels originally come from?

A

Sun

56
Q

Advantages of fossil fuels?

A

📌High energy content
📌liquid fuel- easy to transport
📌 relatively cheap
📌 proven technology- most engines are designed to use petrol from crude oil.

57
Q

Disadvantages of fossil fuels?

A

📌Burning releases CO2- leads to global warming and climate change.
📌Extra CO2 dissolves in oceans and makes them acidic- could kill marine life.
📌If fossil fuel contains sulfur- then sulfur dioxide produced- causes acid rain.
📌Non-renewable:we are using it up faster than it forms.
📌Oil can only be found in certain areas- leads to political problems.
📌Oil needs to be drilled and transported, can lead to environment problems if there is a spill.
📌wasteful to burn products from oil as can be useful yo make other things e.g plastics, medicines

58
Q

Biofuels

A

Fuels made from plant or animal products.

59
Q

Biodiesel

A

Made from oil from old plants or even old cooking oil.

60
Q

Biogas

A

Generated from animal waste

61
Q

Where does the energy stored in biofuels originally come from?

A

Sun

62
Q

How can plants make fuel?

A

Plants make glucose during photosynthesis, ethanol can be produced from glucose by feementation.

63
Q

Advantages of biofuels?

A

📌Renewable, we can grow more plants
📌Burn cleanly, don’t contain sulfur
📌 Will eventually by cheaper than fossil fuels when they start to run out.
📌Carbon neutral- the carbon dioxide released when plant products burnt is taken in during photosynthesis.
📌Biodegradable- better then oil if spilt.
📌Can be produced anywhere- not reliant on countries with lots of oil.

64
Q

Disadvantages of Biofuels?

A

📌Uses up farmland
📌Destruction of rain forest and other habitats for farmland.
📌Biodiesel freezes in cold climates.
📌Not as high energy content as fossil fuels.
📌In hot temps can go ‘sticky’.
📌Expensive at the moment.
📌Can absorb water causing engine corrosion.

65
Q

How can hydrogen be obtained?

A

From water by electrolysis

66
Q

What are the main types of fuels available?

A

Fossil fuels
Biofuels
Hydrogen

67
Q

How can hydrogen be used as a fuel?

A

Used in fuel cells to make electricity- these can be used to power electric motors in cars instead of batteries.

68
Q

Advantages of hydrogen as a fuel?

A

📌No pollutants made- just water.
📌Burns well- clean flame.
📌Can be obtained from water- no shortage.
📌Can be used to make electricity in a fuel cell.

69
Q

Disadvantages of Hydrogen as a fuel?

A

📌Hydrogen is a gas so has to be compressed to be used in cars- this can be dangerous and expensive.
📌Electrolysis to obtain hydrogen from water uses energy- this has to be produced somehow!

70
Q

Combustion of hydrogen…

A

Hydrogen + oxygen 👉 water

2H2 + O2 👉 2H2O

71
Q

Hydrocarbons

A

Compounds that contain hydrogen and carbon only.

72
Q

Alkenes

A

Unsaturated hydrocarbons because they contain less that the maximum amount of hydrogen possible. Alkenes do contain a double bond between two carbon atoms.

73
Q

What is the general formulae for an alkene?

A

CnH2n

74
Q

Why is there no such molecule as methane?

A

Because there is only one carbon in methane and one carbon cannot have a double bond with itself.

75
Q

What is a simple test to distinguish between alkanes and alkenes?

A

To add bromine water- if alkene the colour of the products formed will turn from orange to colourless.
If alkane then no change, stay orange.

76
Q

Why does alkenes turn colourless in bromine water?

A

Alkanes do not de-colourise bromine water. Alkenes do because they are more reactive then alkanes because atoms can add to the double bond.

77
Q

Fractional distillation

A

Is the process in which crude oil is separated into ‘fractions’ due to different boiling points of different sized molecules in the oil.
Physical separation process NOT a chemical reaction.

78
Q

Larger hydrocarbon molecules tend to have…

A

Higher boiling points than smaller hydrocarbon molecules.

79
Q

Cracking

A

The process in which large alkane molecules from crude oil are broken down into smaller molecules.

80
Q

Cracking process?

A

In industry the alkane is heated to form a vapour then passed over a hot catalyst or mixed with steam at high temperatures.

81
Q

What type of reaction is cracking?

A

A thermal decomposition reaction as more than one new substance is made when a single alkane breaks down.

82
Q

What does cracking of a large alkane molecule always produce?

A

A smaller alkane and at least one alkene.

83
Q

Why do we perform cracking?

A

Large hydrocarbons in heavier fractions form viscous liquids and solids with high boiling points, they don’t ignite easily and burn with a smoky flame so they are not much use as fuel.

Cracking forms smaller alkane molecules which ignite easily an burn well so they are much more in demand as they are more useful as fuels.

Cracking also produces other useful hydrocarbons called alkenes.

84
Q

Cracking demonstration?

A

✖️Ceramic wool soaked in paraffin at end of boiling tube.
✖️Broken pottery heated in middle of boiling tube.
✖️Delivery tube connects boiling tube to a water tub in which another boiling tube is sitting on top of water.
✖️Bunsen flame under water.
✖️Gas collected at top of the boiling tube.
BEWARE OF SUCK BACK-remove delivery tube from water before stop heating.

85
Q

In cracking how do you know an alkene has been formed?

A

Because the bromine water turns from orange to colourless

86
Q

How can you tell the new product is a samller molecule then in the paraffin?

A

Paraffin was a liquid and then the new product was a gas.

87
Q

What fractions are usually cracked?

A

Large heavy fractions with bigger molecules (high b.p)

Chemistry (12 decks)

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