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GCSE Chemistry > Organics 1 - 4th > Flashcards

Organics 1 - 4th Flashcards

1
Q

what is crude oil?

A
  • a mixture of hydrocarbons, compounds of hydrogen (H) and carbon (C) only
  • the different hydrocarbons in crude oil come in a huge variety of shapes and sizes, which results in crude oil boiling over a very large range of temperatures
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2
Q

why do we need to separate crude oil?

A
  • most of the hydrocarbons are useful, but often for very different purposes
  • this means we need to separate the oil into fractions which contain similarly used molecules.
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3
Q

what is each fraction of crude oil?

A
  • a mixture of similar hydrocarbons with similar boiling points
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4
Q

what happens to the fractions of crude oil as the boiling points increase?

A
  • the fractions get darker in colour
  • the fractions get more viscous (like treacle)
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5
Q

what happens to the fractions of crude oil as the boiling points increase?

A
  • the fractions get darker in colour
  • the fractions get more viscous (like treacle)
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6
Q

what is the boiling point, molecular mass, colour, viscosity and use of refinery gases?

A
  • low BP
  • low molecular mass
  • light colour
  • low viscosity
  • used for fuel for home cooking
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7
Q

what is the use of gasoline?

A
  • used for fuel for cars
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8
Q

what is the use of kerosene ?

A
  • used for fuel for aircraft
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9
Q

what is the use of diesel?

A
  • used for fuel for trains
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10
Q

what is the use of fuel oil?

A
  • fuel for ships
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11
Q

what is the boiling point, molecular mass, colour, viscosity and use of bitumen?

A
  • high BP
  • high molecular mass
  • dark colour
  • high viscosity
  • used for making roads
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12
Q

how are each of the fractions separated from crude oil?

A
  • by fractional distillation
  • done industrially on a large scale
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13
Q

how does fractional distillation work?

A
  • fractionating column is hotter at the bottom and colder at the top
    onenote chemistry rev pic
    THIS IS HOW IT WORKS:
  • heated crude oil vapours enter the column
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14
Q

what is the order of each of the fractions from lowest to highest BP/order of fractional distillation?

A
  • refinery gases
  • gasoline
  • kerosene
  • diesel
  • fuel oil
  • bitumen
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15
Q

what are fractions?

A
  • mixtures containing the hydrocarbons that boil in a particular temperature range
  • for example, kerosene contains hydrocarbons that boil between 250 degrees and 350 degrees.
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16
Q

what are alkanes?

A
  • hydrocarbons that fit the general formula C v nH v 2n+2
  • (v means subscript)
  • made of simple molecules containing C and H atoms held together by covalent bonds
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17
Q

how are alkanes named?

A
  • the start of the name shows how many carbon atoms it has
  • the end of the name is ‘-ane’ to show it is an alkane
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18
Q

what is the name and bonding of CH4?

A
  • methane
  • *chem rev image
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19
Q

what is the name and bonding of C2H6?

A
  • ethane
  • *chem rev image
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20
Q

what is the name and bonding of C3H8?

A
  • propane
  • *chem rev image
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21
Q

what is the name and bonding of C4H10?

A
  • butane
  • *chem rev image
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22
Q

what is the name and bonding of C5H12?

A
  • pentane
  • *chem rev image
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23
Q

what names of alkane bondings come after methane, ethane, propane, butane and pentane?

A
  • names follow the 2d shapes
  • hexane, heptane, octane, etc
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24
Q

what are the 4 types of formulae for each alkane?

A
  1. displayed formula
  2. structural formula
  3. molecular formula
  4. empirical formula
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25
Q

what does the displayed formula show?

A
  • a diagram showing the position of every atom and every bond
  • e.g. chemistry flashcard 21
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26
Q

what does the structural formula show?

A
  • this shows the structure of the molecule in one line, read from left to right like a word
  • e.g. CH3CH2CH2CH3
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27
Q

what does the molecular formula show?

A
  • this only shows how many carbon and hydrogen atoms there are
  • e.g. C4H10
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28
Q

what does the empirical formula show?

A
  • this only shows the simplest whole-number ratio of carbon to hydrogen
  • e.g. C2H5
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29
Q

what are alkanes in terms of homologous series?

A
  • alkanes are a homologous series of organic molecules
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30
Q

what does a homologous series of organic molecules mean?`

A
  • this means they are a family of molecules which have:
    - similar chemical reaction
    - trends in physical properties (e.g. boiling points, viscosity or colour)
    - the same general formula
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31
Q

what are the other series in the IGCSE course ?

A
  • alkanes
  • alcohols
  • carboxylic acids
  • esters
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32
Q

what are isomers?

A
  • isomers are molecules with the same molecular formula but different structural formulae
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33
Q

how many isomers does C4H10 have?

A
  • butane has two isomers
  • *chem rev image
34
Q

how many isomers does C5H12 have?

A
  • pentane has three isomers
  • *chem rev image
35
Q

what makes isomers different?

A
  • the branching in the carbon chain
  • you can’t make a different isomer just by bending the molecules
36
Q

what are most alkanes made of and why?

A
  • most can be used as fuels because they release a lot of energy when combusted
37
Q

what are the two types of combustion that alkanes can undergo and what is it dependent on?

A
  • depending on how much oxygen is available :
    - complete combustion
    - incomplete combustion
38
Q

what is complete combustion?

A
  • this occurs when there is excess oxygen
  • it produces only CO2 and H2O
  • alkane + oxygen -> carbon dioxide + water
  • e.g. the complete combustion of propane
    - propane + oxygen -> carbon dioxide + water
    - C3H8 + 5O2 -> 3CO2 + 4H2O
39
Q

what is the equation of complete combustion with alkenes?

A
  • alkane + oxygen -> carbon dioxide + water
40
Q

what is incomplete combustion?

A
  • this occurs when there isn’t enough oxygen
  • instead of CO2 this produces a nasty mixture of:
    - carbon monoxide (CO) - a toxic gas which lowers oxygen-carrying capacity of blood
    - soot (C) - which causes lung diseases
  • it also releases less energy so it makes the alkane less useful as fuel
41
Q

what is the equation of incomplete combustion with alkenes?

A
  • alkene + oxygen -> carbon monoxide + soot
42
Q

what three significant pollutants does the combustion of alkenes as fuels release into the atmosphere?

A
  • carbon dioxide (CO2)
  • nitrogen oxides (NOx)
  • sulphur dioxide (SO2)
43
Q

explain how carbon dioxide is formed as a significant pollutant.

A
  • this forms directly from the combustion of the alkane fuel
  • it is a greenhouse gas that traps heat in the atmosphere and causes climate change
44
Q

explain how nitrogen oxides are formed as a significant pollutant.

A
  • this family of compounds form when nitrogen from the air combusts
  • usually nitrogen doesn’t combust but car engines are really, really hot
  • they dissolve in rainwater to form acid rain, which corrodes structures and is harmful to plant and aquatic life
45
Q

explain how sulphur dioxide is formed as a significant pollutant.

A
  • this forms when sulphur impurities in the fuel combust
  • like nitrogen oxides, it dissolves in rainwater to form acid rain
46
Q

how do alkanes react with halogens?

A
  • by swapping one hydrogen atoms for one halogen atom
  • for example, when ethane (C2H6) reacts with bromine (Br2)
    - C2H6 + Br2 -> C2H5Br + HBr
    - *chem rev image
47
Q

when would the the halogen + alkane reaction work?

A
  • would work with any alkane (e.g. pentane) and any halogen (e.g. chlorine)
  • all that happens is a hydrogen swaps with hydrogen
48
Q

what are the two details you need to know about alkane and halogen reactions?

A
  • it’s a substitution reaction - because the H swaps with Br
  • the reaction requires UV light - because the alkane is pretty unreactive
49
Q

does crude oil contain longer or shorter alkanes?

A
  • contains much longer alkanes than shorter ones
50
Q

which is more useful - the longer or shorter alkanes?

A
  • the shorter ones
51
Q

what do we do to get around having more longer alkanes than shorter alkanes?

A
  • the shorter ones are more useful
  • to get around this, we take the longer alkanes and do cracking
  • cracking breaks down longer alkanes into smaller, more useful ones
52
Q

under which conditions is cracking conducted?

A
  • temperature: 650 degrees
  • catalyst: aluminium oxide(Al2O3)
  • it can be conducted without a catalyst but far more energy would need to be provided
53
Q

what does cracking produce?

A
  • can provide a variety of products, but nearly always it works like this:
    - long alkane -> shorter alkane + alkene
  • for example, it could be pentane -> ethane + propene
  • anything is possible as long as it makes an alkene and an alkane and as long as the numbers of C and H add up
54
Q

what are alkenes?

A
  • they are hydrocarbons that fit the general formula CvnHv2n
  • v = subscript
55
Q

what is the formula, name and bonding of an alkene if n is 2 in the formula?

A
  • formula = C2H4
  • name = ethene
  • bonding = *chem rev image
56
Q

what is the formula, name and bonding of an alkene if n is 3 in the formula?

A
  • formula = C3H6
  • name = propene
  • bonding = *chem rev image
57
Q

what is the formula, name and bonding of an alkene if n is 4 in the formula?

A
  • formula = C4H8
  • name = butene
  • bonding = *chem rev image
58
Q

what is the formula, name and bonding of an alkene if n is 5 in the formula?

A
  • formula = C5H10
  • name = pentene
  • bonding = *chem rev image
59
Q

why do the names of alkenes end in ‘-ene’?

A
  • to indicate they have the C=C bond
60
Q

how is the double bond sometimes shown in a structural formula?

A
  • as ‘=’
  • e.g. butene is written:
    - CH2 = CHCH2CH3
61
Q

what are alkenes in terms of homologous series?

A
  • alkenes are a homologous series of organic molecules, like alkanes, but slightly different
  • however, they are still a family of molecules which have:
    - similar chemical reactions
    - trends in physical properties (e.g. boiling points, viscosity or colour)
    - the same general formula
62
Q

what are alkene isomers?

A
  • like alkanes, alkenes also have isomers
  • but unlike alkanes, their isomers can differ in more than one way:
    - through the branching of the carbon chain (chem rev image)
    - because of the position of the C=C in the carbon chain (    chem rev image)
63
Q

how many different isomers does C4H8 have?

A
  • three different isomers
64
Q

why are alkenes referred to as unsaturated?

A
  • because they have a C=C double bond
65
Q

why are alkanes referred to as saturated?

A
  • because they don’t have a C=C double bond
66
Q

how do alkenes release energy?

A
  • like alkanes, they also combust in oxygen to release energy
  • same as alkanes - can combust completely and incompletely in the same manner
67
Q

how do alkenes react with bromine?

A
  • by breaking the C=C and adding the bromine atoms in
  • e.g. ethene (C2H4) reacting with bromine (Br2) - *chem rev image
    - C2H4 + Br2 -> C2H4Br2
68
Q

when would the alkene and bromine reaction work?

A
  • with any alkene
  • all that happens is the C=C breaks and the Br atoms add in where it was
69
Q

what are the details you need to know about the alkene and bromine reaction?

A
  • it’s an addition reaction - because you’re adding the bromine atoms into the alkene
  • the reaction happens without UV light - because alkenes are more reactive than alkanes
  • it works with pure bromine liquid or bromine water (bromine water is orange)
  • the mixture turns orange to colourless - because the bromine is used up in the reaction
70
Q

what is the alkene and bromine reaction used for?

A
  • as a test for the C=C in unsaturated compounds
  • *chem rev image
71
Q

what forms when molecules with a C=C double bond add into chains?

A
  • an addition polymer
  • *chem rev image
72
Q

what are the small molecules which add together to form an addition polymer called?

A
  • monomers
73
Q

how is an addition polymer usually represented?

A
  • using a repeating unit
  • *chem rev image
  • the little ‘n’ represents a v.big number
74
Q

how is the name of an addition polymer formed?

A
  • by putting ‘poly’ in front of the monomer name
  • e.g. polymer formed by ethene -> called poly(ethene)
75
Q

what are the four commonly encountered polymers you should know about?

A
  • poly(ethene)
  • poly(propene)
  • poly(chloroethene)
  • poly(tetrafluoroethene)
76
Q

what is the monomer, repeating unit and uses of poly(ethene)?

A
  • *chem rev image
  • uses: drinks bottles and shopping bags
77
Q

what is the monomer, repeating unit and uses of poly(propene)?

A
  • *chem rev image
  • uses: storage boxes and climbing ropes
78
Q

what is the monomer, repeating unit and uses of poly(chloroethene)?

A
  • *chem rev image
  • uses: wire insulation and drainpipes
79
Q

what is the monomer, repeating unit and uses of poly(tetrafluoroethene)?

A
  • *chem rev image
  • uses: non-stick coating
80
Q

what does it mean by addition polymers are inert?

A
  • they’re chemically very unreactive
  • they don’t break down very easily
81
Q

what are your only options for disposal of an unwanted addition polymer?

A
  1. reuse it, or give it to someone else who will use it
  2. recycle it, which allows it to be reshaped for another use
  3. incinerate it, and use the energy released to generate electricity
  4. chuck it onto landfill, and hope it goes away

GCSE Chemistry (13 decks)

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