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Chemistry > C6.2 - Organic chemistry > Flashcards

C6.2 - Organic chemistry Flashcards

1
Q

what is crude oil?

A
  • fossil fuel from remains of marine organisms that lived millions of years
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2
Q

how is crude oil formed?

A

chemical reactions + action of heat and pressure turned remains of dead marine organisms into crude oil

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3
Q

Methane formula

A

CH4

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4
Q

Ethane formula

A

C2H6

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5
Q

Propane formula

A

C3H8

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6
Q

Butane formula

A

C4H10

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7
Q

what does crude oil contain?

A

mixture of hydrocarbons - mostly alkanes

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8
Q

what are hydrocrabons?

A

substances made of only hydrogen and carbon atoms

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9
Q

what happens when alkanes get bigger?

A

bpt increases - TMT you can separate different molecules using fractional distillation

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10
Q

what is an alkane?

A

a hydrocarbon

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11
Q

what is the general formula for an alkane?

A

CnH2n+2

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12
Q

What is the Ethane displayed formula

A 
H    H     
       |     |
H - C - C - H
       |     |
      H   H
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13
Q

what is the ethane structural formula?

A

CH3CH3

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14
Q

What is the ethane skeletal formula?

A

/

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15
Q

What is the Propane displayed formula

A 
H   H   H
       |     |     |
H - C - C - C - H
       |     |     |
      H   H    H
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16
Q

What is the structural formula of Propane?

A

CH3CH2CH3

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17
Q

What is the skeletal formula for propane?

A

/\

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18
Q

What is the Butane displayed formula?

A 
H   H  H   H
       |     |    |     |
H - C - C - C - C - H
       |     |     |     |
      H   H   H    H
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19
Q

What is the structural formula for Butane?

A

CH3CH2CH2CH3

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20
Q

What is the skeletal formula for butane?

A

/\/

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21
Q

properties of alkanes

A
  • saturated molecules (as only contain single covalent bonds)
  • unreactive (as only contain strong single covalent bonds)
  • Bpt and viscosity increases as you increase the chain length
  • flammability + volatility decrease as you increase chain length
  • form homologous series - as have similar chem properties + trend in physical properties as you change the chain by -CH2
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22
Q

when do alkanes undergo combustion reactions?

A

when they react with oxygen in the air and burn

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23
Q

complete combustion equation

A

Alkane + oxygen –> carbon dioxide + water

CH4 + 2O2 –> CO2 + 2H2O

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24
Q

what is complete combustion?

A

when lots O2 available, reaction is complete & produces CO2 and water
- E.g. Bunsen burner with an open air-hole

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25
Q

incomplete combustion reaction

A

Alkane + oxygen –> Carbon dioxide + water + carbon monoxide + soot
4CH4 + 6O2 –> CO2 + 8H2O + 2CO + C

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26
Q

What is incomplete combustion?

A

when not enough O2 available - e.g. Bunsen burner with closed air-hole (safety flame)

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27
Q

how do you separate alkanes from crude oil?

A

fractional distillation - bpt increases as chain length increases - TIB the longer the chain the stronger the intermolecular forces

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28
Q

How does fractional distillation work?

A
  • crude oil piped into fractionating column
  • bottom of column has highest temp
  • smaller molecules have lowest bpt so evaporate 1st rising to top of column - continue to rise until it becomes cool enough to condense back into liquid (when they are collected)
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29
Q

what are alkanes used as?

A

fuels - basic form of a hydrocarbon found in crude oil

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30
Q

what is cracking?

A

turning longer alkane chains into shorter ones (shorter chains are more useful)

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31
Q

example formula of cracking

A

decane –> octane + ethene

C10H22–>C8H18 + C2H4

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32
Q

Industrial conditions for cracking

A

high temps required (often means heating samples to 600-700°C in presence of hot catalyst of alumina/silica)
- under these conditions, strong covalent bonds between atoms can break

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33
Q

what does cracking produce?

A

shorter alkane chains and alkenes

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34
Q

why are alkenes useful?

A

helpful in production of polymers - e.g. plastics

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35
Q

what are alkenes produced from?

A

by-product of cracking

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36
Q

alkene general formula

A

CnH2n

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37
Q

Alkene characteristics

A
  • form homologous series - TIB of common features

- unsaturated molecules as contain double bond between 2 carbon atoms

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38
Q

Ethene structural formula

A 
H    H 
 |      |
C = C
 |      |
H    H
39
Q

Ethene structural formula

40
Q

Propene displayed formula

41
Q

Propene displayed formula

A 
H    H   H
       |     |     |
H - C - C = C
       |           |
      H         H
42
Q

Butene structural formula

43
Q

Butene displayed formula

A 
H    H   H   H
      |      |     |     |
H - C - C - C = C 
       |     |           |
      H    H         H
44
Q

Pentene structural formula

45
Q

Pentene displayed formula

A 
H    H   H   H    H
       |     |     |     |      |
H - C - C - C - C = C 
       |     |     |           |
      H   H   H          H
46
Q

How do you check cracking has taken place effectively?

A

test for alkene - bromine water

  • Alkane + bromine water –> no reaction (bromine water remains orange)
  • Alkene + bromine water –> reaction (bromine water turns from orange to colourless)
47
Q

what happens in an addition reaction?

A

atom / group of atoms combine with a molecule to forma larger molecule - - no other products are made

48
Q

what is hydrogenation?

A

where hydrogen adds across the double bond to turn an alkene into an alkane

49
Q

what does alkene and water make?

50
Q

alkenes + oxygen =

A

carbon dioxide + water

51
Q

is it more likely for a complete or incomplete combustion reaction to take place?

A

incomplete - smaller carbon: hydrogen ratio - fewer H2 atoms for every C atom

52
Q

which is more likely to undergo an incomplete combustion reaction - hexane or hexene?

53
Q

how can alcohols be identified?

A

by their O-H functional group

54
Q

why can alcohols take part in different reactions?

A

as they have a different functional group

55
Q

methanol structural formula

56
Q

Ethanol structural formula

57
Q

Propanol structural formula

A

CH3CH2CH2OH

58
Q

Methanol displayed formula

A 
H
       |
H - C - O - H
       |
      H
59
Q

Ethanol displayed formula

A 
H    H
       |     |
H - C - C - O - H
       |     |
      H   H
60
Q

Propanol displayed formula

A 
H   H   H
       |     |     |
H - C - C - C - O - H 
       |     |     |
      H   H    H
61
Q

how many bonds do hydrogen, oxygen and carbon form

A

hydrogen - 1
oxygen - 2
carbon - 4

62
Q

general formula for alcohols

63
Q

Ethanol from steam and ethene reaction

A
  • phosphoric acid - catalyst - speeds up reaction rate

- high pressures used to improve yield + reaction rate

64
Q

Ethanol from fermentation

A
  • relies on action of yeast - yeast = single celled fungi containing enzymes which act as a catalyst
  • plant sugars can produce ethanol in fermentation
  • C6H12O6 (glucose) –> 2CO2 +2C2H5OH (ethanol)
  • must be carried out below 50°C so yeast doesn’t denature - typically done in 35°C (anaerobic conditions)
65
Q

uses of alcohols

A
  • drink
  • fuel - flammable, release lots energy, burn with clean flame (complete combustion
  • solvents - substances dissolve easily in alcohol
  • disinfectants - kill bacteria effectively
66
Q

oxidation of alcohols

A
  • alcohols can be oxidised from carboxylic acids
67
Q

carboxylic acid general formula

A

CnH2n+1COOH

68
Q

Ethanol –> Ethanoic acid

A

H H H O
| | | //
H - C - C - O - H —> H - C - C
| | | \
H H H OH

69
Q

Methanoic acid displayed formula

A 
O
         //
H - C 
          \
            O - H
70
Q

Methanoic acid structural formula

71
Q

Ethanoic acid displayed formula

A 
H         O
       |        //
H - C - C
       |        \
       H       O - H
72
Q

Ethanoic acid structural formula

73
Q

propanoic acid displayed formula

A 
H   H        O 
       |     |       //
H - C - C - C 
       |     |       \
      H   H       O - H
74
Q

Propanoic acid structural formula

A

CH3CH2COOH

75
Q

making carboxylic acids - method 1 - both use oxidising agent

A

alcohol + potassium manganate (VII) solution
- mix together + warm in a water bath
- add little bit of dilute sulfuric acid
colour change - purple to v.pale pink or colourless

76
Q

making carboxylic acids - method 2 - both use oxidising agent

A

alcohol + potassium dichromate solution
- mix together + warm in a water bath
- add a little bit of dilute sulfuric acid
colour change - orange to green

77
Q

reactions of carboxylic acids

A
  • weak acids

- react with metal to produce hydrogen + salts

78
Q

what react together to make esters?

A

alcohols and carboxylic acids - called condensation reaction as 2 molecules react to form 1 large & 1 smaller molecule - smaller one is often water

79
Q

making esters

A
  • put drop concentrated sulfuric acid into test tube
  • add approx 10 drops carboxylic acid to tt
  • add approx 10 drops alcohol to tt
  • add some hot water to beaker - put tt in hot water bath
  • after few min remove tt and leave to cool on a tt rack
  • half fill a 2nd tt with sodium carbonate solution - once cooled pour ester solution into sodium carbonate solution
  • pour contents back into OG tt + leave to settle - smell ( gentle waft)
80
Q

what do alkenes join to form?

A

large chains - polymers

81
Q

are alkenes monomers or polymers?

82
Q

What is polymerisation?

A

a chemical reaction where monomer molecules join to form polymer chains

83
Q

what does the type of polymer formed depend on?

A

depends on the monomer initially used

  • e.g. ethene –> poly(ethene)
  • e.g. propene –> poly(propene)
84
Q

What are the three types of polymers?

A
  • addition polymers - formed from alkenes
  • biological polymers - formed in nature
  • condensation polymers - often formed from carboxylic acids
85
Q

what are some examples of natural forming polymers?

A

DNA, proteins and carbohydrates such as starch

86
Q

what are proteins?

A

polymers made from monomers (amino acids)

87
Q

what are carbohydrates?

A

compounds of carbon, hydrogen and oxygen

- include simple sugars (sucrose) and complex carbs (starch)

88
Q

what is sucrose made from?

A

glucose + fructose combining

89
Q

what are DNA molecules made from?

A

DNA molecules are polymers made from monomers called nucleotides (which contain base pairings)

90
Q

what are condensation polymers?

A

polymers that form from condensation reactions

91
Q

monomers need to have two…

A

…functional groups present - one at each end of the structure
- when monomers join - a small molecule is eliminated (often water)

92
Q

what are polyesters and how do they form?

A
  • form when di-carboxylic acids react with di-alcohols
  • called polyesters as contain many ester groups
  • used for clothing and in production of drink bottles
93
Q

what are polymides and how do they form?

A
  • form when di-carboxylic acids react with di-amines
  • called polymides as contain amide groups
  • E.g. Nylon used to make clothing + carpets

Chemistry (9 decks)

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