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EDEXCEL Chemistry a level > T6 Organic Chem > Flashcards

T6 Organic Chem Flashcards

1
Q

hydrocarbons

A

compound containing only carbon and hydrogen

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2
Q

saturated

A

containing only single bonds

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3
Q

unsaturated

A

containing one or more multiple bonds

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4
Q

displayed formula

A

shows every atom and bond separately

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5
Q

structural formula

A

all atoms joined to a singular carbon are grouped

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6
Q

skeletal formula

A

only shows bonds between carbon atoms

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7
Q

molecular formula

A

shows numbers of each atom, not structure

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8
Q

empirical formula

A

molecular formula with each atom in its simplest whole-number ratio

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9
Q

functional group

A

an atom or group of atoms in a molecule that is responsible for its chemical reactions.

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10
Q

homologous series

A

family of compounds with the same functional group, differing by CH2.
they have similar chemical/physical properties displaying gradation.

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11
Q

alkane general formula

A

CnH2n+2

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12
Q

alkene general formula

A

CnH2n

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13
Q

halogenoalkane general formula

A

CnH2n+1X

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14
Q

alcohol general formula

A

CnH2n+1OH

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15
Q

structural isomers

A

compounds with the same molecular formula but differing structural formula

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16
Q

chain isomers

A

structural isomers with different carbon chains.

similar chemical properties but different physical.

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17
Q

position isomers

A

molecules with the same functional group attached in a different position on the same carbon chain
different physical/chemical properties

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18
Q

stereoisomerism

A

compounds with the same structural formula but with the atoms/groups arranged differently in 3 dimensions.

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19
Q

geometric isomers

A

compounds containing a CC double bond with atoms or groups attached at different positions.

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20
Q

bond angles shown on geometric isomers

A

at 120 degrees

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21
Q

trans

A

when the 2 Carbon groups are on opposite sides to one another.

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22
Q

cis

A

when the 2 carbon groups are on the same side to one another.

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23
Q

why do geometric isomers only occur at double bonds?

A

because the CC double bond presence restricts rotation so groups attached can’t move around

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24
Q

process of E/Z notation

A
  1. ) work out names of both isomers
  2. ) use priority rules as to which of 2 atoms on left of C=C has the higher priority (higher having a greater atomic number)
  3. ) copy on the right
  4. ) are they in the cis or trans positions?
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25
Q

E notation

A

equivalent of trans notation for non-carbons

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26
Q

Z notation

A

equivalent of cis notation for non-carbons

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27
Q

3 main processes used to convert crude oil into fuels

A

cracking
reforming
fractional distillation

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28
Q

fractional distillation

A

crude oil heated in furnace and passed into fractionating column in which there’s a temp gradient (hot at bottom and cooler at top), passing through column via a series of bubble caps, condensing at different heights, depending on bp.
larger molecules at bottom and smaller at top

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29
Q

cracking

A

hydrocarbons are passed over a heated catalyst (e.g zeolite/ aluminium oxide) causing them to break down.

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30
Q

why does reforming take place

A

as straight chains burn less efficiently than cyclic compounds so reforming occurs to convert straight chains into cyclic compounds

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31
Q

process of reforming

A

heating w a catalyst (eg. platinum)

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32
Q

complete combustion word equation

A

alkane + oxygen&raquo_space; carbon dioxide + water

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33
Q

incomplete combustion word equation

A

alkane + oxygen&raquo_space; carbon + carbon dioxide + water + carbon monoxide

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34
Q

what’s released in incomplete combustion?

A

soot
carbon monoxide (toxic replacement of oxygen in blood, colourless/odourless)
unburned hydrocarbons

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35
Q

how is sulfur dioxide formed?

effects on environment?

A

during alkane combustion, sulfur impurities react with oxygen in the air to form SO2 and further react in air to form sulfur trioxide.
both are acidic oxides and so dissolve in water to form sulphurous/ sulfuric acid.

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36
Q

nitrogen oxide formation

A

only under v high temps, nitrogen reacts in the air to form nitrogen oxides
these dissolve to form nitrous/nitric acid

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37
Q

catalytic converters

A

use metal meshes (eg, platinum, rhodium, palladium) to remove pollutants.

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38
Q

reactions that take place in catalytic converters

A

oxidation of carbon monoxide (2CO+O2»2CO2)
oxidation of unburned HC
Removal of nitrogen impurities

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39
Q

disadvantage of catalytic converter

A

poor at sulfur impurity removal so must be removed before is burnt

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40
Q

why do we need alternative fuels?

A

depletion of natural resources

global warming

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41
Q

biofuel

A

fuel obtained from living matter (that hasn’t died recently)

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42
Q

biodiesel

A

a fuel formed from vegetable oils obtained from plants

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43
Q

bioalcohol

A

fuels formed from plant matter, often using enzymes/bacteria.

44
Q

facts to consider in use of alternative fuels

A

carbon neutrality
manufacture/transport
yield
land use

45
Q

disadvantages/advantages of bioethanol/biodiesel

A

much land required that could be used to grow food
low yield (increasing?)
no exploration/drill costs, rather extraction and transport costs are high
more carbon neutrality

46
Q

evaluate natural gas use

A

no land needed
high yield
high drilling cost, low processing and transport cost
bad for environment

47
Q

relative reactivity of alkanes

A

relatively unreactive as is just made up of C and H joined by single bonds

48
Q

substitution reaction

A

when an atom/group is replaced by another atom/group

49
Q

mechanism

A

sequence of steps in an overall reaction showing electrons involved in the formation/breaking of bonds.

50
Q

INITIATION in chlorination of methane

A

chlorine molecule is split apart and each chlorine takes one electron from the pair to form 2 chlorine radicals.

51
Q

homolytic fission

A

the breaking of a covalent bond where each of the bonding electrons leaves with one species, forming a radical.

52
Q

radical

A

a species with an unpaired electron

53
Q

initiation step

A

the formation of radicals, usually as a result of bond breaking caused by UV radiation

54
Q

under what conditions does the chlorination of methane occur in?

A

v high temp conditions or using UV radiation

55
Q

propagation

A

the two steps that, when repeated many times, convert the starting materials into the products of a reaction

56
Q

propagation step in chlorination of methane

A

v reactive radicals collide w methane molecules and react by removing a hydrogen atom
Cl+CH4»HCl+CH3
methyl radical can further react with chlorine molecules
CH3+Cl2»CH3Cl+Cl

57
Q

termination

A

when a molecule is formed from 2 radicals.

58
Q

examples of termination reactions in chlorination of methane

A

Cl+Cl»Cl2
Cl+CH3»CH3Cl
CH3+CH3»C2H6

59
Q

why is chlorination of methane ineffective in industrial use?

A

has a low yield and products must be separated.

60
Q

alkenes double bond effect on reaction

A

makes them more reactive than alkanes so can be used in useful reactions.

61
Q

sigma bonds

A

covalent bonds formed when electron orbitals overlap axially

62
Q

bonding in alkenes

A

double bond uses a pi bond and sigma bond

63
Q

how are pi bonds formed in alkenes

A

the 2 sigma bonds surrounding the 2 carbon atoms in the C=C as each carbon has one electron in a p orbital not used in bond formation. p orbitals parallel to one another result in 2 regions of negative charge above and below the sigma bond forming a pi bond.

64
Q

pi bond

A

covalent bonds formed when electron orbitals overlap sideways.

65
Q

why are alkenes more reactive?

A

the pi bond spreads the electrons further from the carbon atoms so that they are more available for reactions

66
Q

what happens to the bonds when alkenes react in addition reactions?

A

sigma bond remains unchanged in reactions while the pi bond is used to form new bonds with an attacking molecule to form a saturated product.
sigma is more stable and stronger as electrons are less readily available to react.

67
Q

how to test for presence of a C=C double bond

A

place in bromine water, if it decolorises then a C=C double bond is present

68
Q

hydrogenation

A

the addition of hydrogen to an alkene

69
Q

catalyst in hydrogenation of alkenes

A

nickel and requires heat

70
Q

how are addition reactions used in margarine manufacture

A

unsaturated vegetable oils react with hydrogen, so they then thicken.

71
Q

halogenation

A

reaction between alkenes and halogens to form halogenoalkanes

72
Q

hydration

A

addition of water/steam

73
Q

how are alkenes hydrated?

A

heat alkene with steam and run over a catalyst of phosphoric acid

74
Q

hydrogen halide addition

A

forms a halogenoalkane

75
Q

diol oxidation

A

addition of oxygen and water to an alkene to form a diol with 2 hydroxyl groups. oxygen atom comes from air while water molecule gives H2O

76
Q

conditions for diol oxidation

A

potassium manganate used in acidic condition (sulfuric acid).

77
Q

what happens to potassium manganate in the presence of alkenes

A

changes from purple to colourless

78
Q

curly arrows

A

start from a bond/lone pair and move to an atom

79
Q

electrophile

A

a species that is attracted to a region of high electron density

80
Q

how do hydrogen halides act as electrophiles

A

slight positive end of the HX is attracted to the electrons in the pi bond in the C=C, as is electronegative

81
Q

heterolytic fission

A

the breaking of a covalent bond so that both bonding electrons are taken by one atom

82
Q

electrophilic addition

A

reaction in which two molecules form one molecule and the attacking molecule is an electrophile.

83
Q

carbocation

A

positive ion in which the charge is shown on a carbon atom

84
Q

first step of electrophilic addition

A

HBr bonding electrons are given to the Br atom (so is negative ion) and the Hydrogen joins to the alkene, forming a carbocation.

85
Q

second step of electrophilic addition

A

2 oppositely charged ions attract each other and react to form new covalent bond

86
Q

process of electrophilic addition of halogens

A

Br2 forms a slightly positive/negative end and so positive end is attracted to surrounding electrons in the pi bond, forming a carbocation which then reacts with the remaining ion

87
Q

what do unsymmetrical molecules form in electrophilic addition?

A

a major and minor product

88
Q

how does the number of alkyl groups attached to the carbocation affect the amount produced

A

more alkyl groups spread the positive charge more so it is more stable, therefore more product is formed

89
Q

property of alkyl groups

A

electron-releasing

90
Q

how to name a polymer

A

stick ‘poly’ in front of the alkene name

91
Q

reasons for increased polymer use

A

can be manufactured easily on large scale in variety of shapes/colors
lightweight
unreactive
cheap and disposable

92
Q

3 main ways of using polymer waste

A

recycling
incineration
chemical feedstock

93
Q

recycling

A

sorting (as mixtures of polymers are ineffective) via hand (inefficient/tedious)
processing (chopping waste into small pieces and washing)

94
Q

incineration

A

takes in waste and converts into heat energy for homes/factories/electricity
waste ends up as gas (polluting)

95
Q

chemical feedstock

A

chemical reaction use

96
Q

biodegradable

A

broken down by microbes in the environment.
requires land for plant material
cant be incinerated, recycled or used as feedstock

97
Q

difference between homolytic and heterolytic fission

A

both breaking of a covalent bonds but homolytic fission transfers electron to both species so that two of the same species are formed but heterolytic transfers both electrons to one atom, forming two different species

98
Q

typical energy of a UV photon

A

300 kj/mol

99
Q

steps of propagation reactant and product relations

A

product in step one is reactant in step two and product in step two is reactant in step 1

100
Q

problem w radical substitution

A

end up w a mixture of products

meaning more energy must be used to separate them

101
Q

aromatic compounds

A

contain benzene rings

102
Q

zeolite catalyst

A

hydrated aluminosilicate

103
Q

thermal cracking

A

takes places at high temp and pressure (1000 degrees and up to 70atm), producing many alkenes

104
Q

catalytic cracking

A

uses zeolite catalyst at a slight pressure and high temperature, producing aromatic hydrocarbons and motor fuels
cuts cost and speeds up reaction

105
Q

why is cracking done

A

greater demand for motor fuels, petrochemicals and polymers

106
Q

products from reforming

A

cycloalkanes, arenes, aromatic compounds, branched alkanes

107
Q

CC double bond shape (120 degrees)

A

trigonal planar (120 degrees)

EDEXCEL Chemistry a level (12 decks)

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