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C12- ALKANES > 12.4- COMBUSTION OF ALKANES > Flashcards

12.4- COMBUSTION OF ALKANES Flashcards

1
Q

How reactive are alkanes?

A

quite unreactive

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2
Q

What do alkanes not react with?

A

acids, bases, oxidising agents or reducing agents

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3
Q

What do alkanes burn and react with under suitable conditions?

A

burn and will react with halogens under suitable conditions

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4
Q

How well do shorter chain alkanes burn in a plentiful supply of oxygen?

A

burn completely

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5
Q

What is produced when shorter chain alkanes are burnt in a plentiful supply of oxygen?

A

carbon dioxide and water

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6
Q

What does combustion reactions give out?

A

give out heat

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7
Q

What is the enthalpies of combustion like?

A

large negative enthalpies

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8
Q

What is greater when there’s more carbon present in combustion?

A

greater the heat output

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9
Q

Why are alkanes with more carbon important in fuels?

A

when combusted they have a great heat output

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10
Q

What are fuels?

A

substances that release heat energy when they undergo combustion

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11
Q

What do fuels store a large amount of in a small amount of weight?

A

store a large amount of energy for a small amount of weight

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12
Q

Examples of alkane fuels? (5)

A 
methane
propane 
butane 
petrol
paraffin
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13
Q

What fuel is methane used for?

A

natural or North Sea gas

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14
Q

What fuel is propane used for?

A

camping gas

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15
Q

What fuel is butane used for?

A

calor gas

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16
Q

What types of hydrocarbons make up petrol?

A

mixture of hydrocarbons of approximate chain length C8

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17
Q

What does a limited supply of oxygen in combustion cause the production of?

A

poisonous gas carbon monoxide

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18
Q

What sort of combustion is it when carbon monoxide is formed?

A

incomplete combustion

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19
Q

What is produced when even less oxygen is provided in combustion?

A

carbon (soot)

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20
Q

Example of carbon (soot) being formed from incomplete combustion in lab?

A

when Bunsen burner used with a closed air hole, flame is yellow and black sooty deposit appears on apparatus

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21
Q

When does incomplete combustion often happen?

A

often happens when with longer chain hydrocarbons

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22
Q

Why does incomplete combustion often happen with longer chain hydrocarbons?

A

they need more oxygen to burn compared with shorter chains

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23
Q

What do all hydrocarbon-based fuels derived from crude oil may produce when they’re burnt?

A

polluting products

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24
Q

Different types of polluting products made from when hydrocarbon-based fuels derived from crude oil are burnt? (7)

A 
carbon monoxide 
nitrogen oxides 
sulfur dioxide 
carbon particles 
unburnt hydrocarbons 
carbon dioxide 
water vapour
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25
Q

What is carbon monoxide?

A

poisonous gas produced by incomplete combustion

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26
Q

Examples of nitrogen oxides?

A

NO, NO2, N2O4

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27
Q

How are nitrogen oxides formed?

A

produced when there is enough energy for nitrogen and oxygen in the air to combine

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28
Q

Equation of how nitrogen and oxygen combine to form nitrogen oxides?

A

N2 (g) + O2 (g) = 2NO (g)

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29
Q

Example of where does nitrogen and oxygen combine to form nitrogen oxides?

A

petrol engine at high temperatures present, when sparks ignite fuel

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30
Q

What may the nitrogen oxides from petrol engine react with to form?

A

oxides may react with ester vapour and oxygen in the air to form nitric acid

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31
Q

As the nitrogen oxides from petrol engines eventually produce nitric acid, what are they contributors of?

A

contributors of acid rain and photochemical smog

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32
Q

What is sulphur dioxide a contributor of?

A

acid rain

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33
Q

Where is sulphur dioxide produced from?

A

produced from sulphur-containing impurities present in crude oil

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34
Q

How does sulphur dioxide produce acid rain?

A

this oxide combines with water vapour and oxygen in the air to form sulphuric acid

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35
Q

What are carbon particles called?

A

particulates

36
Q

What can particulates exacerbate and cause?

A

exacerbate asthma and cause cancer

37
Q

What type of gas is carbon dioxide?

A

greenhouse gas

38
Q

What is always produced when hydrocarbons are burnt?

A

carbon dioxide

39
Q

What is the increasing levels of carbon dioxide in the atmosphere causing?

A

cause of an increase in the Earth’s temperature and consequent climate change

40
Q

What type of gas is water vapour?

A

greenhouse gas

41
Q

How do a large number of power stations generate electricity?

A

by burning fossil fuels such as coals or natural gas

42
Q

What do coals and natural gas contain?

A

sulphur compounds

43
Q

What is a product of combustion of coals and natural gases as they contain sulphur compounds?

A

sulphur dioxide, SO2

44
Q

What does sulphur dioxide cause?

A

acid rain

45
Q

How does sulphur dioxide cause acid rain?

A

by combining with oxygen and water in the atmosphere to form sulphuric acid

46
Q

Equation for how sulphur dioxide reacts with oxygen and water to form sulphuric acid?

A

S02 (g) + 1/2O2 (g) + H20 (l) = H2SO4 (l)

47
Q

What is the gases given out by power stations called?

A

flue gas

48
Q

What is the process of removing the sulphur dioxide from flue gas called?

A

flue gas desulphurisation

49
Q

What is one method of flue gas desulphurisation?

A

slurry of calcium oxide (lime) + water is sprayed into the flue gas which reacts with calcium oxide + water to form calcium sulphite, which can be further oxidised to calcium sulphate

50
Q

What is calcium sulphate also called?

A

gypsum

51
Q

What is the overall reaction of flue gas desulphurisation into gypsum?

A

CaO (s) + 2H20 (l) + S02 (g) + 1/2O2 = CaSO4.2H20(s)

52
Q

What is gypsum used to make?

A

builder’ plaster and plasterboard

53
Q

What is an alternative method of flue gas desulphurisation?

A

use calcium carbonate (limestone) rather than calcium oxide

54
Q

What is the equation for flue gas desulphurisation using calcium carbonate?

A

CaCO3 (s) + 1/2O2 (g) + SO2 (g) = CaSO4 (s) + CO2 (g)

55
Q

What does the internal combustion produce most of?

A

most of the pollutants listed previously

56
Q

What is removed from petrol to make it less of a problem?

A

sulphur removed from petrol so sulphur dioxide has become less of a problem

57
Q

What are all new cars with petrol engines now equipped with?

A

catalytic converters in their exhaust systems

58
Q

What do the catalytic converters in the exhaust systems of petrol engine cars do?

A

reduce output of carbon monoxide, nitrogen oxides and unburnt hydrocarbons in the exhaust gas mixture

59
Q

What is the catalytic converter?

A

honeycomb made of a ceramic material coated with platinum and rhodium metals

60
Q

What are the catalysts on a catalytic converters?

A

platinum and rhodium

61
Q

What does the honeycomb structure of catalytic converters provide?

A

provide enormous surface area, so little of these expensive metals (platinum + rhodium) go a long way

62
Q

What happens when the polluting gases pass over the catalyst of the catalytic converter?

A

react with each other to form less harmful products

63
Q

Equation for how carbon monoxide reacts with nitrogen oxide over catalytic converter?

A

2CO (g) + 2NO (g) = N2 (g) + 2CO2 (g)

64
Q

Word equation for how hydrocarbons react with nitrogen oxide over catalytic converter?

A

hydrocarbons + nitrogen oxide = nitrogen + carbon dioxide + water

65
Q

Where does the reactions take place on the catalytic converter?

A

on the surface of the catalyst, on the layer of platinum and rhodium metals

66
Q

What is the temperature like inside a greenhouse?

A

greenhouses become very warm inside

67
Q

Why does it become very warm inside a greenhouse?

A

because visible rays from sun pass through the glass

68
Q

What happens to the visible rays that pass through the glass of a greenhouse?

A

rather than escaping, their energy is absorbed by everything inside the greenhouse and re-radiated as infrared energy (heat)

69
Q

What is the wavelength of infrared energy in comparison to visible rays?

A

infrared energy has a longer wavelength

70
Q

Can infrared energy pass out of the glass of greenhouses?

A

no

71
Q

How does carbon dioxide behave in terms of a greenhouse?

A

like glass

72
Q

How does carbon dioxide act like glass of a greenhouse?

A

it traps infrared radiation so that the Earth’s atmosphere heats up

73
Q

Why is carbon dioxide and other greenhouse gases important?

A

without it the Earth would be too cold to sustain life

74
Q

What are examples of other greenhouse gases other than carbon dioxide? (2)

A

water vapour and methane

75
Q

Are methane and water vapour more effective than carbon dioxide?

A

yes

76
Q

How has the levels of methane and water vapour in the atmosphere changed over the years?

A

not been much change

77
Q

What has happened since the industrial revolution?

A

fossil fuels have been used to fuel industrial plants and the level of carbon dioxide has been rising

78
Q

As the levels of CO2 has been rising, what has also been increasing?

A

Earth’s temperature

79
Q

What is the most abundant greenhouse gas?

A

water vapour

80
Q

How does the concentration of water vapour change in the atmosphere?

A

tends to stay the same

81
Q

Where does the concentration of water vapour in the atmosphere not stay the same?

A

near waterfalls

82
Q

Why does the concentration of water vapour in the atmosphere tend to stay the same?

A

because of the equilibrium that exists between water vapour and liquid water

83
Q

What happens to water vapour when there’s an increase in temperature?

A

will be more water vapour in the air and so more greenhouse warming

84
Q

What can the increase in water vapour in the air be offset by?

A

offset by greater cloud formation and clouds reflect solar radiation

85
Q

Why are many people concerned about activities such as airline flights?

A

they produce large amounts of carbon dioxide

86
Q

What are activities that produce no carbon dioxide emission overall refereed to as?

A

carbon neutral

C12- ALKANES (5 decks)

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