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edexcel igcse chemistry > unit four: organic chemistry > Flashcards

unit four: organic chemistry Flashcards

1
Q

methane molecular formula

A

CH4

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2
Q

ethane molecular formula

A

C2H6

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3
Q

propane molecular formula

A

C3H8

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4
Q

butane molecular formula

A

C4H10

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5
Q

pentane molecular formula

A

C5H12

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6
Q

what are isomers

A

compounds which have the saem molecular formula but different structural formula

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7
Q

what is a homologous series

A

a series of compounds that:
have the same functional group
have similar chemical properties
show a trend (gradation) in physical properties
can be described by the same general formula
differ from the next by a CH2 unit

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8
Q

alkane general formula

A

Cn H2n + 2

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9
Q

members of the same homologous series show a trend in

A

physial properties

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10
Q

members of the same homologous series have

A

similar chemical properties

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11
Q

ethene molecular formula

A

C2H4

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12
Q

propene molecular formula

A

C3H6

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13
Q

but-1-ene molecular formula

A

C4H8

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14
Q

what is a hydrocarbon

A

a substance that contains carbon and hydrogen only

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15
Q

alkene functional group

A

C=C

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16
Q

what does unsaturated in organic chem mean

A

alkene - they contian a C=C bond.

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17
Q

what does a saturated compound contain

A

only single C-C bonds

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18
Q

what does an unsaturated compound contain

A

contains one or more double or triple C=C bonds

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19
Q

alkene general formula

A

CnH2n

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20
Q

how do you test for a C=C bond

A

add bromine water and the orange bromine water will be decolourised.

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21
Q

how can ethene be produced

A

cracking

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22
Q

what is polymerisaton

A

joining up of lots of little molecules (monomers) to make one big molecule (polymer). molecules add onto eachother without anything else being formed. this is called addition polymerisation

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23
Q

what is LDPE

A

low density polyethene

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24
Q

what is HDPE

A

high density polyethene

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25
Q

what is PVC

A

poly(chloroethene)

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26
Q

what temperature does crude oil get heated to

A

350 degrees celsius

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27
Q

pentene molecular formula

A

C5H12

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28
Q

what is the order of hydrocarbons’ boiling points in crude oil

A 
refinery gases
gasoline
kerosene
diesel oil
fuel oil
bitumen
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29
Q

uses of refinery gases

A

natural gas
LPG for domestic heating and cooking
calor gas

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30
Q

uses of gasoline

A

petrol, fuel for cars

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31
Q

uses of kerosene

A

jet fuel, paraffin

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32
Q

uses of diesel

A

diesel, fuel for buses, lorreis, some cars and some railway engines. some is also converted to petrol in cracking,

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33
Q

uses of fuel oil

A

industrial heating oil and fuel for ships

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34
Q

uses of bitumen

A

lubricants, waxes

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35
Q

how many carbon atoms are in refinery gases

A

1-4

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36
Q

how many carbon atoms are in gasoline

A

5-10

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37
Q

how many carbon atoms are in kerosene

A

11-16

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38
Q

how many carbon atoms are in diesel

A

17-20

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39
Q

how many carbon atoms are in fuel oil

A

21-30

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40
Q

how many carbon atoms are in bitumen

A

more than 31

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41
Q

what type of bonding holds all organic compounds together

A

covalent

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42
Q

what colour are small alkanes

A

light

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43
Q

what colour are large alkanes

A

dark

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44
Q

viscosity of small alkanes

A

low

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45
Q

viscosity of large alkanes

A

high

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46
Q

boiling point of small alkanes

A

low

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47
Q

boiling point of high alkanes

A

high

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48
Q

are small alkanes volatile

A

yes

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49
Q

are large alkanes volatile

A

no

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50
Q

are small alkanes flammable

A

high

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51
Q

are large alkanes flammable

A

low

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52
Q

are small alkanes useful as a fuel

A

yes

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53
Q

are large alkanes useful as a fuel

A

no

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54
Q

CLEANNESS

A

OF FLAME

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55
Q

FRACTION

56
Q

what are the two main gases that cause acid rain

A

sulphur dioxide

nitrogen dioxide

57
Q

what is the effect of acid rain on trees

A

stunted growth

58
Q

what is the effect of acid rain on buildings made of limestone or objects made of metal

59
Q

how much of crude oil is petrol

60
Q

why does cracking produce short chain molecules and an alkene

A

there aren’t enough carbon atoms to form more alkanes and so they are forced to form double bonds

61
Q

what would be observed as bromine reacts with methane

A

orange to colourless

62
Q

what would be observed as chlorine reacts with methane

A

pale green to colourless

63
Q

what can organic compounds exist as

A

chains, branched chains or rings of carbon atoms with hydrogens attatched

64
Q

what is the empirical formula

A

the simplest whole number ration of the atoms in a compound.

65
Q

what is the molecular formula

A

the actual number of each type of atom present in a molecule.

66
Q

what is the molecular formula a multiple of

A

the empirical formula.

67
Q

what are homologous series

A

a series of compounds with similar chemical properties because they have the same functional group. each member differs from thenext by one -CH2-

68
Q

general formula of alkanes

69
Q

what is a funtional group

A

an atom or group of atonms that determine the chemical properties of a compound.

70
Q

what is a structural formula

A

shows how the atoms in a molecule are joined together.

71
Q

what is a displayed formula

A

the full structural formula that shows all the bonds in the molecule as indiviual lines.

72
Q

what does each line represent in a displayed formula

A

a pair of shared electrons in a covalent bond.

73
Q

what are alkanes

A

a homologous series of similar hydrocarbons (compounds of carbon and hydrogen only) in which all the carbons are joined to eachother with single covalent bonds.

74
Q

what are alkenes

A

a homogolous serioes of hydrocarbons which contain a carbon-carbon double bond.

75
Q

side chain -methyl

76
Q

side chain -ethyl

77
Q

what is the position of the side chain shown by

A

by numbering the carbon atoms from the end of the longest chain which produces the smaller numbers in the name

78
Q

what are structural isomers

A

molecules with the same molecular formula but different structural formulae

79
Q

what are the three isomers for C5H12

A

pentane
2-methylbutane
2,2-dimethylpropane

80
Q

does ethene have any isomers

81
Q

does propene have any isomers

A

none that are still alkenes

82
Q

what are the isomers of C4H8

A

but-1-ene
2-methylpropene
but-2-ene

83
Q

what are alcohols

A

homologous series of compounds which all contain an -OH functional group attatched to a hydrocarbon chain.

84
Q

what are the two different forms of propanol

A

propan-1-ol

propan-2-ol

85
Q

why are the two different forms of propanol structural isomers

A

because there is no way that you can bend or twist one of the molecules to make the other,

86
Q

when does a substitution reaction occur

A

when an atom or group of atoms is replaced by a different atom or group of atoms.

87
Q

what is an addition reaction

A

when something is added to a molecules without taking anything away. this happens to alkenes.

88
Q

origins of crude oil

A

dead plants and animals turning to limestone after being covered in layers of sediment. the soft tissue was gradually changed by heat and high pressure to crude oil

89
Q

is crude oil renewable

A

no its non-renewable

90
Q

what is crude oil

A

a mixture of hydrcarbons.

91
Q

explain the trend in volatility in crude oil

A

the bigger the hydrocarbons, the more slowly it evaporates at room temperature. this is because the bigger molecules are more strongly attracted to their neighbours and so don’t turn into a gas so easily

92
Q

which burns easily big hydrocarbons or small hydrocarbons

A

smaller ones. this limits the use of the bigger ones as fuels

93
Q

trend in colour of crude oil

A

the liquids become darker in colour as the molecules become bigger

94
Q

fractional distillation of crude oil

A

it is heated until it boils and the vapours pass into a fractionating column, which is cooler at the top and hotter at the bottom. how far up the column a particular hydrocarbon moves depends on its boiling point.

95
Q

what do all hydrocarbons burn in air/oxygen to form

A

carbon dioxide and water

96
Q

what is a fuel

A

a substance that which, when burned, releases heat energy.

97
Q

if there isnt enough air for combustion what happens

A

incomplete combustion –> soot/carbon and carbon monoxide.

98
Q

why is CO poistionous

A

it reduces the ability of the blood to carry oxygen around your body.

99
Q

complete combustion equation

A

Fuel + O2 –> CO2 + H2O

100
Q

environmental problems with burning crude oil-derived fossil fuels

A

carbon dioxide is produced this causes the greenhouse gas to trap the heat radiated from the earths surface (originally from the sun) and can lead to climate change.

101
Q

when is acid rain formed

A

when water and oxygen in the atmosphere react with sulfur dioxide to produce sulfuric acid or with various oxides of nitrogen to give nitric acid.

sulfur dioxide and NOx come mainly from power stations and factories burning fossil fuels, or from motor vehicles.

102
Q

why is acid rain bad

A

it kills trees and fish in lakes (sometimes all the life in the lake) and limestone builidings are damaged.

103
Q

solution to acid rain

A

removing sulfur from fuels, scrubbing the gases from power stations and factories to remove sulfur dioxide and NOx, and using catalytic converters in cars.

104
Q

problems with fractions

A

too many long chains hydrocarbons not in demand and not as profitable.
too few shorter chain hydrocarbons that can be used as fuel.

105
Q

what is cracking

A

the process by which long-chain alkanes are converted to alkenes and shorter-chain alkanes

106
Q

what is the fuel oil fraction passed over

A

a catalyst of silicon dioxide (silica) and aluminium oxide (alumina)

107
Q

what temperature does cracking occur at

A

600-700 degrees

108
Q

what process is cracking

A

thermal decomposition

109
Q

what does cracking produce

A

a mixture of alkanes and alkenes

110
Q

why do oil companies carry out cracking

A

to produce more petrol
to produce more alkenes that can be used for making polymers (plastics) (alkenes are more reactive than alkanes and also have other uses)

111
Q

what is polymerisation

A

the joining up of lots of little molecules (monomers) to make one big molecule (polymer).

112
Q

what is addition polymerisation

A

molecules add onto eachother without anything elese being formed

113
Q

chain length of the polymerisation of ethene

A

4000-40,000

114
Q

types of polyethene

A

LDPE (low density polyethene)

HDPE (high density polyethene)

115
Q

LDPE is used for

A

thin film to make polythene bags

weak

116
Q

HDPE is used for

A

plastic bottles

rigid

117
Q

what is polypropene used to make

A

ropes and crates

118
Q

what does PP mean

A

polypropene

119
Q

what is PVC

A

polyvinylchloride, the old name for polychloroethene

120
Q

uses for PVC

A

water pipes

replacement windows

121
Q

how can PVC be made flexible

A

by adding plasticisers

122
Q

why would PVC be made flexible

A

for sheet floor covering and clothing.

123
Q

does PVC conduct electricity

A

no so it can be used for electrical insulation

124
Q

what is tetrafluroethene

A

a molecule derived from ethene in which all four hydrogen atoms are replaced by fluorine.

125
Q

what is poly(tetrafluroethene) known as

A

Teflon or PTFE

126
Q

what is poly(tetrafluroethene) used for

A

non stick coating for pots and pans

127
Q

why is PTFE used for non stick linings

A

it is unreactive due to the strong carbon-fluorine bonds

128
Q

how to work out a monomer from a polymer

A

take any two C atoms next to eachother and repalce C-C with C=C and get rid of the continuation bonds.

129
Q

disposal of addition polymers

A

they are non-biodegradable due to the long time it takes to break down, and the strong covalent bonds that make them essentially inert at ordinary temperatures.

130
Q

solution to disposal of addition piolymers

A

bury them in landfill sites.

incinerate them

131
Q

incinerating addition polymers

A

the large heat energy produced can be used for generating electricity but also contributes to global warming and release of toxic gases.

132
Q

adv of addition polymers in landfill

A

no greenhouse gases or toxic gases produced

133
Q

disadv of addition polymers in landfill

A

ugly, smelly and noisy, no one wants to live there.

uses large areas of land

the waste will be there for thousands of years

134
Q

adv of addition polymers incinerated

A

requires little space

can produce heat

135
Q

disadv of addition polymers incinerated

A

expensive to build and maintain plant

produces greenhosue gases

releases toxic gases

the ash produced must still be disposed of in landfill sites

edexcel igcse chemistry (4 decks)

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