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AQA A Level Chemistry > Year 12- Organic Chemistry > Flashcards

Year 12- Organic Chemistry Flashcards

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1
Q

What is a hydrocarbon?

A

Compound consisting of hydrogen and carbon atoms only

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2
Q

What is a structural formula?

A

Shows minimal detail of arrangement of atoms in a molecule, CH3CH2CH2CH3

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3
Q

What is a displayed formula?

A

Drew out to show all covalent bonds and atoms present in a molecule

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4
Q

What is the shape around a carbon atom in a saturated hydrocarbon?

A

Tetrahedral- bond angle is 109.5

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5
Q

What is a skeletal formula?

A

Simplified organic formula, shown by removing hydrogen atoms from alkyl chains, only showing carbon atoms and functional groups

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6
Q

What is a homologous series?

A

Families of organic compounds with same functional groups and general formula.

  • They show gradual change in physical properties
  • Each member differs by CH2
  • Same chemical properties
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7
Q

What is the difference of the C=O bond in ketones and aldehydes?

A

Ketones- in the middle

Aldehydes- at the end

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8
Q

Ester functional group

A

Central carbon double bonded to an oxygen and single bonded to another oxygen

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9
Q

Which form- suffix or prefix- do double and triple C-C bonds take?

A

Suffix

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10
Q

Order of priority highest first

A

Carboxylic acids> aldehydes> ketones>alcohols>alkenes> halogenoalkanes

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11
Q

Which one takes precedence of taking the lowest number- functional group or branched chain?

A

Functional group

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12
Q

What do we do if there is more than one functional group or side chain?

A

List them in alphabetical order

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13
Q

What happens if the compound has an -OH group and a functional group that takes precedence?

A

Priority group gets suffix ending and OH can be names with the prefix hydroxy.

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14
Q

What happens in homolytic fission?

A

Each atom gets one electron from the covalent bond. This forms free radicals.

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15
Q

What is a free radical?

A

A reactive species that possesses an unpaired electron

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16
Q

What happens in heterolytic fission?

A

One atom gets both electrons

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17
Q

What is structural isomerism?

A

Same molecular formula but different structures/ structural formulae

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18
Q

What are the different ways structural isomerism can rise?

A
  • Chain isomerism
  • Position isomerism
  • Functional group isomerism
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19
Q

What is chain isomerism?

A

Compounds with same molecular formula but diff structures of the carbon skeleton

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20
Q

What is position isomerism?

A

Compounds with same molecular formula but different positions of same functional groups on the same carbon skeleton.

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21
Q

What is functional group isomerism?

A

Compounds with same molecular formula but atoms arranged t give different functional groups

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22
Q

What is stereoisomerism?

A

Same structural formulae but different spatial arrangement of atoms

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23
Q

What are 2 types of stereoisomerism?

A

E-Z isomerism

Optical isomerism

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24
Q

What type of hydrocarbon exhibits E-Z isomerism?

A

Alkenes

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25
Q

Why do E-Z stereoisomerism arise?

A
  • Restricted rotation around C=C bond

- 2 different groups/atoms attached to both ends of double bond

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26
Q

What is considered the priority group in E-Z isomerism?

A

The atom with the bigger atomic number

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27
Q

What is petroleum?

A

Mixture containing mainly alkane hydrocarbons

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28
Q

Fractional distillation of crude oil

A
  • Oil is heated and passed into column
  • Fractions condense at diff heights depending on their bp.
  • Temp of column decreases upwards
  • Bp depends on size of molecules: larger ones condense at the bottom at hotter temps and vice versa.
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29
Q

What is cracking?

A

Conversion of large hydrocarbons to smaller hydrocarbons by breaking C-C bonds

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30
Q

What do high mr alkanes form in cracking?

A

Smaller mf alkanes, alkenes and hydrogen

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31
Q

Economic reasons for cracking

A
  • Shorter hydrocarbons are more in demand
  • To make use of excess larger hydrocarbons
  • Products are more valuable
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32
Q

Conditions of thermal cracking

A

High temp: 400-900 *C

High pressure: 7000kPa

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33
Q

Products of thermal cracking

A

Mostly alkenes and hydrogen

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34
Q

Conditions of catalytic cracking

A

Moderate pressure
High temp: 450*C
Zeolite catalyst

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35
Q

Product of catalytic cracking

A

Branched and cyclic alkanes and aromatic hydrocarbons

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36
Q

How can SO2 be removed?

A

By flue gas desulfurisation. Gases pass through scrubber containing basic calcium oxide which reacts with the acidic SO2 in a neutralisation reaction. Forms calcium sulfite, CaSO3.

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37
Q

What can calcium sulfite be used for?

A

To make calcium sulfate for plasterboard

38
Q

How is nitrogen oxide formed?

A

Formed between nitrogen and oxygen in car engine. High temp and spark in the engine provides activation energy needed to break strong N-N bond.

39
Q

What do catalytic converters do?

A

Remove CO, nitrogen oxides and unburned hydrocarbons from the exhaust gases, turning them into harmless gases.

40
Q

Mechanism of greenhouse effect

A

UV wavelength radiation passes through atmosphere to Earths surface and heats it up. Earth radiates out IR long wavelength radiation. The C=O bond in CO2 absorbs IR radiation so it doesn’t escape the atmosphere. Energy is transferred to other molecules in atmosphere by collisions so atmosphere is warmed.

41
Q

Initiation stage- free radical substitution

A
  • UV light supplies energy to break CL-Cl bond by homolytic fission
  • Forms free radicals
42
Q

Propagation stage- free radical substitution

A

1) CH4 + Cl* –> HCl + *CH3

2) CH3 +Cl2 –> CH3Cl +Cl

43
Q

What are primary, secondary and tertiary haloalkanes?

A

Primary- one carbon attached to carbon adjoining halogen

and vice versa…

44
Q

What reactions can halogenoalkanes undergo?

A

Elimination and nucleophilic substitution reactions

45
Q

What is a nucleophile?

A

Electron pair donator

46
Q

What is an electrophile?

A

Electron pair acceptor

47
Q

Nucleophilic sub- Halogenoalkane (general)

A
  • Nucleophile attacks positive carbon atom attached to halogen
  • C-X bond breaks and this releases a negative halide ion
48
Q

How can we compare the reactivity of halogenoalkanes?

A
  • React it with aqueous silver nitrate
  • A silver halide ppt forms as the halide leaving group combines with a silver ion
  • The quicker the ppt forms, the faster the sub reaction
49
Q

Precipitates formed from reacting aqueous silver nitrate with halogenoalkanes- colours

A

AgI- yellow
AgBr- cream
AgCl- white

50
Q

What happens in nucleo sub reaction of a halogenoalkane and cyanide ions?- product, reagent, conditions

A

Product- nitrile
Reagent- KCN dissolved in ethanol/water mixture
Conditions- Heat under reflux

51
Q

What happens in nucleo sub reaction of a halogenoalkane and aqu. hydroxide ions?- product, reagent, conditions

A

Product- alcohol
Reagent- potassium/sodium hyroxide
Conditions: aqu. solution, heat under reflux

52
Q

What happens in nucleo sub reaction of a halogenoalkane and ammonia?- product, reagent, conditions

A

Product- amine
Reagent- NH3 dissolved in ethanol
Conditions: Heat under pressure in sealed tube

53
Q

What happens in elim sub reaction of a halogenoalkane and alc. hydroxide ions?- product, reagent, conditions

A

Product- alkene
Reagent- potassium/ sodium hydroxide
Conditions- in ethanol, heat

54
Q

What are chloroalkanes and chlorofluoroalkanes used for?

A

Solvents- CH3CCl3 used as solvent in dry cleaning

55
Q

What is naturally-occurring ozone (O3) used for?

A

Layer in upper atmosphere thats beneficial as it filters out much of the suns harmful UV radiation

56
Q

What is ozone, O3 like in the lower atmosphere

A

It is a pollutant and contributes to formation of smog

57
Q

What do man-made CFCs do?

A

Form a hole in the ozone layer

58
Q

What is now used instead of CFCs in refrigerators and air conditioners?

A

HFCs- safer as they don’t contain C-Cl bond which would break in CFCs by UV light.

59
Q

How do CFCs form a hole in the ozone layer?

A

UV light breaks the C-Cl bonds which forms a chlorine free radical. The catalyses the decomposition of ozone in a free rad sub reaction.

60
Q

Arrangement of bonds around C=C bond in alkenes

A

Planar- 120* bond angle

61
Q

What does a C=C bond contain?

A

a pi and sigma bond

62
Q

Why are pi bonds vulnerable to being attacked by electrophiles

A

They are exposed and have high electron density

63
Q

What reactions do alkenes undergo?

A

Electophilic addition reactions

64
Q

Electro add of bromine with alkenes- products, reagent and conditions

A

Products- dihalogenoalkane
Reagent- bromine
Conditions- room temp (not in UV light)

65
Q

What is the intermediate in electro add. reactions?

A

Carbocations

66
Q

Electro add. of HBr with alkenes- products, reagent and conditions

A

Products- halogenoalkene
Reagent- HBr or HCl
Conditions- room temp

67
Q

If an alkene is unsymmetrical, what can be formed in an electro add reaction?

A

2 products- major or minor product

68
Q

What makes a carbocation more stable?

A

The methyl groups on either side of the positive carbon are electron releasing and reduce the charge on the ion, stabilising it

69
Q

Order of stability of carbocations

A

tertiary>secondary> primary

70
Q

Electro add. reaction of sulfuric acid with alkenes- stage 1

A

Product- alkyl hydrogensulfate
Reagent-conc. H2SO4
Conditions- room temp

71
Q

Electro add. reaction of sulfuric acid with alkenes- stage 2

A

Products- alkyl hydrogensulfate —> alcohol
Reagent- water
Conditions- warm mixture

-Hydrolysis reaction

72
Q

Industrially, how are alkenes converted to alcohols?

-Name conditions

A

In one stage, compared to the electro add. reaction with conc. sulfuric acid. They are reacted with water in the presence of an acid catalyst.

High temp: 300-600
High pressure-70 atm
Catalyst of conc. H3PO4

73
Q

Bond angles in alcohols

A

H-C-H and C-C-O bonds are 109.5 *, tetrahedral

H-O-C bond is 104.5*, bent

74
Q

Partial oxidation of primary alcohols- reagent, product, conditions, observations

A

-Forms aldehyde
Reagent- potassium dichromate solution and dilute sulfuric acid
Conditions-warm gently and distilled out
Observations- orange dichromate ions reduces to green chromium 3+ ions

75
Q

Full oxidation of primary alcohols- products, reagent, conditions and observations

A

-Forms carboxylic acid
Reagent- potassium dichromate solution and dilute sulfuric acid
Conditions- use excess dichromate, heat under reflux
Observations- orange dichromate ions reduces to green Cr3+ ions

76
Q

Why are anti bumping granules used?

A

To prevent vigorous, uneven boiling by making small bubbles form instead of big ones

77
Q

Oxidation of secondary alcohols

A
  • Forms ketones
  • Use potassium dichromate solution and dilue sulfuric acid
  • Heat under reflux
  • Orange dichromate ions (Cr2O7 2-) reduce to green chromium ions
78
Q

Why aren’t tertiary alcohols oxidised?

A

No hydrogen bonded to carbon with OH group

79
Q

Tollen’s reagent test- reagent, conditions, reaction, observations

A
  • Reagent formed by mixing aqu. ammonia and silver nitrate to form complex ion [Ag(NH3)2]+
  • Heat gently
  • Aldehydes only oxidised to carboxylic acid
  • Silver ions reduced to silver atoms
  • Silver mirror coats test tube
80
Q

Fehlings solution- reagent, conditions, reaction and observations

A
  • Contains blue Cu 2+ ions
  • Heat gently
  • Aldehydes only oxidise to carboxylic acids
  • Blue Cu 2+ ions reduced to red pot of Cu2O
81
Q

How can carboxylic acids be tested for?

A

Using sodium carbonate. It fizzes and produces carbon dioxide.

82
Q

Reaction of alcohols with dehydrating agents

A
  • Forms alkene
  • Uses conc. sulfuric or phosphoric acid
  • Warm under reflux
  • This is an acid catalysed reaction
83
Q

Forming ethanol by fermentation - reaction and conditions

A

Glucose —> ethanol + carbon dioxide

  • Optimum temp is 38*. At lower temps, too slow and higher temps, yeast dies and enzymes denature
  • Done in absence of air as it could oxidise ethanol to ethanoic acid
84
Q

Advantages of fermentation method for ethanol

A
  • Sugar is renewable

- Production uses low level tech

85
Q

Disadvantages of fermentation method for ethanol

A
  • Batch process is slow and gives high production costs
  • Ethanol made isn’t pure and needs ro be purified by fractional distillation
  • Depletes land used for crop
86
Q

Forming ethanol from ethene- reaction and conditions

A
  • Hydration reaction
  • High temp- 300*
  • High pressure-70 atm
  • Strong acidic catalyst of H3PO4
87
Q

Advantages of hydration of ethene for ethanol

A
  • Faster reaction
  • Purer product
  • Continuous process, cheaper manpower
88
Q

Disadvantages of hydration of ethene for ethanol

A
  • High tech
  • Ethene is non renewable
  • High energy costs for pumping for high pressure
89
Q

What is a biofuel?

A

Fuel produced from plants

90
Q

Why is ethanol produced from fermentation a biofuel?

A
  • Carbon neutral

- Any carbon dioxide given off when biofuel is burnt was extracted from the air by photosynthesis when the plant grew

AQA A Level Chemistry (14 decks)

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