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Chemistry - C1 > Crude oil, Hydrocarbons and Polymers > Flashcards

Crude oil, Hydrocarbons and Polymers Flashcards

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1
Q

What is crude oil?

A

A mixture of compounds called hydrocarbons.

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2
Q

What are hydrocarbons?

A

A compound made up of only hydrogen and carbon joined together by covalent bonds.

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3
Q

What are alkanes?

A

Saturated hydrocarbons. This means that their carbon atoms are joined together by single bonds. This makes them relatively unreactive.

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4
Q

Name 4 alkanes.

A

Methane
Ethane
Propane
Butane

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5
Q

What is the molecular formula for Ethane?

A

C2H6

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6
Q

What is distillation?

A

Distillation is a process that can be used to separate pure liquid from a mixture of liquids. It works when the liquids have different boiling points.

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7
Q

What is a common use for distillation?

A

To separate ethanol from water.

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8
Q

What is the process of distillation?

A

The mixture is heated in a flask; and because ethanol has a lower boiling point it evaporates first. The ethanol vapour is then cooled and condensed inside the condenser to from a pure liquid.
heating → evaporating → cooling → condensing

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9
Q

What is the difference between fractional distillation and distillation?

A

Fractional distillation separates a mixture into a number of different parts called fractions.

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10
Q

What is the process of fractional distillation?

A

A tall column is fitted above the mixture with several condensers coming off at different heights. The column is hot at the bottom and cool at the top. Substances with high boiling points condense at the bottom and substances with lower boiling points condense on the way to the top.
The crude oil is evaporated and it’s vapours condense at different temperatures in the fractioning column. Each fraction contains hydrocarbon molecules with a similar number of carbon atoms.

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11
Q

What happens as you go up the fractioning column?

A

The hydrocarbons have lower boiling points, lower viscosity and higher flammability.

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12
Q

When do fuels burn?

A

When they react with oxygen in the air.

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13
Q

What do the waste products released by burning fuels contribute to?

A

Global warming, global dimming and acid rain.

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14
Q

What is complete combustion?

A

If there is plenty of air, carbon is oxidised to carbon dioxide.

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15
Q

What is carbon dioxide?

A

A greenhouse gas that contributes to global warming.

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16
Q

What is incomplete combustion?

A

When hydrogen is still oxidised to water, but, carbon monoxide is formed instead of carbon dioxide. Carbon monoxide is a toxic gas.

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17
Q

What causes global dimming and how?

A

Particulates stop the sunlight reaching the Earth’s surfaces.

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18
Q

What is acid rain?

A

Although the rain is naturally slightly acidic, some of the products of burning fossil fuels makes rainwater more acidic than normal.

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19
Q

What are the effects of acid rain?

A

It reacts with metals and rocks such as limestone causing damage to buildings and statues. It damages the waxy layer of leaves on trees. This makes it difficult for trees to absorb the minerals they need for healthy growth. It also makes lakes and rivers too acidic for some aquatic life to evolve.

20
Q

What are coal and crude oil?

A

Non-renewable resources

21
Q

What is going to happen as fossil fuels run out?

A

They are going to begin to become more expensive.

22
Q

What harmful substances do petrol, diesel and other fuels release when they are burned?

A 
Carbon dioxide
Carbon monoxide
Water vapour
Particulates
Sulfur dioxide
Oxides of nitrogen
23
Q

What are biofuels?

A

Fuels produced from plant materials.

24
Q

What is biodiesel made from?

A

Rapeseed oil and other plant oils. It can be used in diesel powered engines without any modifications needing to be made on the engine.

25
Q

What is bioethanol?

A

Ethanol is not a hydrocarbon because it contains oxygen as well as hydrogen and carbon. However, it is a liquid fuel that burns well. Bioethanol is made by fermenting sugars from sugar cane, wheat and other plants. It cannot be used on its own unless the engine is modified. However, modern petrol engines can use petrol containing up to 10 percent ethanol without needing any modifications, and most petrol sold in the UK contains ethanol.

26
Q

What are the ethical concerns surrounding biofuels?

A

Crops that could be used to feed people are being used to provide the raw materials of biofuels instead. This could cause food shortages of increased food prices.

27
Q

What are the economic concerns surrounding biofuels?

A

Human resources - More people are needed to produce biofuels than are needed to produce petrol and diesel.
Increased income - For farmers.
Lower fuel prices - Biofuels limit the demand for fossil fuels helping to reduce increases in fuel prices.

28
Q

What are the environmental concerns surrounding biofuels?

A

Biodiesel naturally contain a little sulfur. It may be said that they are carbon neutral. This means that the plants will absorb the same amount of carbon dioxide that biofuels release. If so, this would reduce the production of this greenhouse gas. However, while biofuels produce less carbon dioxide overall, they are not carbon neutral. This is because fossil fuels are used in their production, for example in making fertilisers for the growing plants.

29
Q

What do fractions produced by distillation go through?

A

A process called cracking.

30
Q

What is cracking?

A

A chemical reaction that produces smaller hydrocarbons called alkanes and alkenes.

31
Q

Why are fuels containing large hydrocarbon molecules not efficient?

A

Because they do not flow easily and are difficult to ignite.

32
Q

How does cracking help break down crude oil?

A

It allows large hydrocarbon molecules to be broken down into smaller, more useful hydrocarbon molecules.

33
Q

Why are fractions containing large hydrocarbon molecules heated?

A

To vapourise them.

34
Q

What happens once large hydrocarbon molecules have been vapourised?

A

They are passed over a hot catalyst.

Mixed with steam and hated to a very high temperature

35
Q

What are alkanes and alkenes used for?

A

Alkanes are used for fuel.

Alkenes are used to make polymers in plastic manufacture.

36
Q

What does the general formula mean?

A

The number of hydrogen atoms in an alkene is double the number of carbon atoms.

37
Q

What are alkenes?

A

They are unsaturated hyrdocarbons. They are joined together by a double covalent bond. They react with oxygen in the air, therefore they can be used as fuels. They can also be used to make ethanol and polymers.

38
Q

How can we test for unsaturated hydrocarbons?

A

Bromine water. Bromine water is a dilute solution of bromine. It is an orange-brown colour. When shaken with an alkene it goes colourless. When shaken with an alkane it stays the same colour.

39
Q

What are polymers?

A

Large molecules joined together by smaller molecules. The smaller particles are called monomers.

40
Q

Why can alkenes act as monomers?

A

Because they are unsaturated (they have a double bond)

41
Q

Give examples of polymers and their uses.

A

Polythene - plastic bags and bottles
Polypropene - crates and ropes
Polychloroethene - water pipes and insulation on electricity cables

42
Q

What do polymer properties depend on?

A

The chemicals they are made from and the conditions at which they are made.

43
Q

Give an example of how polymers can have different properties.

A

There are two main types of polyethene.
Low density polyethene
High density polyethene
Low density polyethene is weaker than high density polyethene and becomes softer and lower temperatures.

44
Q

Give an 2 advantages and a 2 disadvantages of polymers.

A

Polymers are unreactive. Therefore they can be used to store food and chemicals safely. Unfortunately, this make polymers difficult to dispose of.
Polymers are widely recycled but different polymers must be separated first.
Most polymers are not biodegradable.

45
Q

What is ethanol?

A

The type of alcohol found in wines and beers.

46
Q

What do ethanol molecules contain?

A

Carbon, hydrogen and oxygen atoms.

47
Q

How can ethanol be made?

A

By reacting ethene with steam.

Chemistry - C1 (6 decks)

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