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Chemistry C1 > C1 Topic 5 - Fuels > Flashcards

C1 Topic 5 - Fuels Flashcards

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1
Q

What is polymerisation?

A

The joining together of lots of monomers to form polymers.

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2
Q

What are monomers?

A

Small molecules.

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3
Q

How do monomers form polymers?

A

They open up their double bonds. This is also through pressure and a catalyst.

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4
Q

Characteristics and uses of poly(ethene)?

A

Stretchy and light

Used in plastic bags

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5
Q

Characteristics and uses of poly(propene)?

A

Tough but flexible

Used for carpets and plastic containers

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6
Q

Characteristics and uses of poly(chloroethene)?

A

Flexible and resistant to wear

Used for clothing and pipes

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7
Q

Characteristics and uses for poly(tetrafluroethene)?

A

Unreactive, flame resistant and resistant to wear

Non stick cooking pans

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8
Q

What are alkenes used to make?

A

Polymers (large molecules)

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9
Q

What is fractional distillation?

A

Fractional distillation separates crude oil into simpler, more useful mixtures using a fractionating column.

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10
Q

What is a hydrocarbon?

A

Compounds that contain carbon and hydrogen only.

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11
Q

How do the fractions differ?

A

Fractions differ in the number of carbon and hydrogen atoms their molecules contain, their boiling points, ease of ignition and viscosity.

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12
Q

What is crude oil?

A

A complex mixture of hydrocarbons.

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13
Q

What are alkanes?

A

Saturated hydrocarbons that contain single bonds.
They are saturated because they have no spare bonds.
They do not form polymers because of no spare bonds to open up.

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14
Q

What are the first three alkanes?

A

Methane - CH4
Ethane - C2H6
Propane - C6H8

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15
Q

What happens when an alkane is added to bromine water?

A

It still stays brown.

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16
Q

What are alkenes?

A

Chains of carbon atoms that have one or more double bonds.
They are unsaturated hydrocarbons because they have some spare bonds.
They form polymers by opening up their double bonds to form a long chain.

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17
Q

What are the first two alkenes?

A

Ethene C2H4

Propene C3H6

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18
Q

What happens when an alkene is added to bromine water?

A

It decolourises it. They form bonds with the bromine atoms.

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19
Q

In fractional distillation, the shorter the molecule is the …

A

More flammable the hydrocarbon is.
E.g. Gases are highly flammable because of short molecule.
Also the less viscous it is. (Bottom fraction is the most viscous)

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20
Q

What is complete combustion?

A

When there’s plenty of oxygen.
The hydrogen and carbon have been oxidised.
Many gas room heaters release the waste gases but as long as it is ventilated there isn’t a problem.

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21
Q

What is the complete combustion equation?

A

Hydrocarbon + oxygen -> carbon dioxide + water (+energy)

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22
Q

What are the waster products of complete combustion?

A

Carbon dioxide

Water

23
Q

What flame is burnt in complete combustion?

A

A clean blue flame because there is plenty of oxygen.

24
Q

What is incomplete combustion?

A

When there isn’t enough oxygen in the reaction.

There is less energy than complete combustion.

25
Q

What is the equation for incomplete combustion?

A

Hydrocarbon + oxygen -> carbon + carbon + carbon + water
monoxide dioxide

26
Q

What are the waster products of incomplete combustion?

A

Carbon - soot
Carbon monoxide
Carbon dioxide
Water

27
Q

What flame is produced in incomplete combustion?

A

A smokey yellow flame because there isn’t enough oxygen.
The flame creates a messy soot.
Less energy is given out.

28
Q

What is dangerous about the carbon monoxide produced in incomplete combustion?

A

Colourless
Odourless
Very toxic
(Therefore should regularly check gas appliances)

29
Q

What makes a good fuel?

A

Ease of ignition
Energy value - amount released.
Ash and smoke - what coal leaves behind that has to be disposed.
Storage and transport - gas needs to be in special canisters.

30
Q

Burning fuels releases…

A

Gases and particles.

31
Q

When fossil fuels are burnt…

A

Carbon dioxide and water vapour.

32
Q

Where are sulfur impurities found?

A

In petrol and diesel so sulfur dioxide is put into the air.

33
Q

If there’s not enough oxygen for the fuel to burn properly…

A

Particles of soot and carbon monoxide is also released.

34
Q

What does sulfur dioxide cause?

A

Acid rain

35
Q

How does sulfur dioxide produce acid rain?

A

When the sulfur dioxide mixes with the clouds it forms dilute sulfuric acid. Then it falls as acid rain.

36
Q

What are the impacts of acid rain?

A

It causes lakes to become acidic and many plants and animals die as a result. It kills trees and damages limestone buildings and ruins stone statues.

37
Q

What are sulfur emissions removed before + The disadvantages?

A

They are removed from fuels before they are burnt, but it costs more to do it. Removal also costs more energy. Therefore this requires burning more fuel, which releases more carbon dioxide.
However they are starting to be replaced by low sulfur versions.

38
Q

How is acid rain prevented?

A

By cleaning up emmisions. Power stations have Acid Gas Scrubbers to take the harmful gases out before they release their fumes into the atmosphere. This is done by using limestone.
Most cars are fitted with catalytic converters to clean up exhaust gases. Or to reduce the usage of fossil fuels.

39
Q

How does carbon dioxide act as a greenhouse gas?

A

Gases in the atmosphere like carbon dioxide, methane and water vapour naturally act like an insulating layer. They absorb most of the heat that would normally be radiated back out into space and re radiate the heat back down to earth.

40
Q

What type of human activity can affect the amount of greenhouse gases?

A

Deforestation

41
Q

What are the human activities that affect carbon dioxide levels?

A

Deforestation- carbon dioxide is released when trees are burnt. Microorganisms feeding on bits of dead wood release carbon dioxide as a waste product of respiration. As trees use carbon dioxide in photosynthesis to produce oxygen, there is less of it.
Burning fossil fuels- carbon was locked up in the fossil fuels when plants and animals were crushed millions of years ago.

42
Q

What is done to reduce carbon dioxide levels? 1)

A

Iron seeding- iron is needed by plants for photosynthesis. Injecting this into the upper ocean promotes the growth phytoplankton. These bloom and absorb CO2 for photosynthesis. However some plankton are toxic and can form dead zones in the sea.

43
Q

What can be done to reduce carbon dioxide levels? 2)

A

Converting carbon dioxide into hydrocarbons.
This is done by the use of high pressure, high temperature and a metal catalyst. This can only be done if the conversion uses green energy.

44
Q

How is biogas made?

A

It is made by microorganisms. Micro organisms are used to decompose living organisms waste or dead plants to create biogas.

45
Q

How can biogas be used?

A

It can be burned to heat water or used in central heating systems. It can power a turbine which can generate electricity. This is good for remote areas with no mains supply. It can also be used as fuel for cars and buses.

46
Q

Advantages of biogas over fossil fuels?

A

Biogas is a renewable source. The plants that decompose to make biogas can be replaced quickly with new crops. The dead plants needed to make biogas photosynthesised when alive, removing carbon dioxide from the atmosphere. This balances out the release of carbon dioxide from burning the biogas (carbon neutral). It is a clean fuel which doesn’t produce significant amounts of sulfur dioxide. The raw materials are cheap and easily available.

47
Q

How is alcohol made?

A

From sugar.

48
Q

How is ethanol produced and what is it used for?

A

Ethanol can be used as a fuel and only burns to give CO2 and water.
It can be produced by using yeast to ferment sugars. Sugar cane and sugar beet can be used in it’s production. Advantages of using ethanol are that less crude oil is used up. Crops needed for ethanol production absorb carbon dioxide through photosynthesis while growing. This makes it slightly carbon neutral.

49
Q

What are disadvantages of using ethanol as a fuel?

A

Distilling ethanol after fermentation requires a lot of energy. Large amounts of land are needed to grow the crops needed to produce ethanol, therefore less land to grow food.

50
Q

What happens when hydrogen and oxygen are combined?

A

They produce water and release energy. It doesn’t produce any pollutants.

51
Q

What is a fuel cell?

A

An electrical cell that’s supplied with fuel and oxygen and uses up energy from the reaction between them to generate electricity.

52
Q

What is a fuel cell used for?

A

We’re used in spacecraft to provide electrical power. This is due to them being more practical than solar cells and safer than nuclear power. A fuel cell does not need recharging as long as fuel is supplied for it to produce energy in the form of electricity.

53
Q

Advantages of hydrogen-oxygen fuel cells?

A

They’re more efficient than power stations. The electricity is generated directly from the reaction. There are no moving parts like a fossil fuel burning power station would have so no energy is lost as friction. Fuel cell vehicles do not produce greenhouse gases, nitrogen oxides, sulfur dioxides and no carbon monoxide. The only by products are water and heat.

54
Q

Reasons why conventional power stations and fossil fuels will still be used?

A

Hydrogen gas takes up a lot of space to store than petrol would. It’s very explosive so it’s difficult to store safely. The hydrogen fuel is often made by hydrocarbons or the electrolysis of water, which uses electricity that has to be generated.

Chemistry C1 (6 decks)

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