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gsce chemistry > organics 4.5 > Flashcards

organics 4.5 Flashcards

(60 cards)

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1
Q

what’s the composition of crude oil?

A

mixture of hydrocarbons
H & C

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2
Q

crude oil, hydrocarbons:

A

different hydrocarbons have a huge variety of shapes and sizes
results in boiling over very large range
most of them are useful, but used for very different purposes
therefore we need to separate the oil into fractions

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3
Q

as the boiling point of crude oils increases…

A
  • the fractions get darker in colour
  • fractions get more viscous
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4
Q

what’s the use and position of refinery gases?

A

1 - lowest , light colour and low viscosity
fuel for home cooking

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5
Q

what’s the use and position of gasoline?

A

2
fuel for cars

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6
Q

what’s the use and position of kerosene?

A

3
fuel for aircraft

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7
Q

what’s the use and position of diesel?

A

4
fuel for trains

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8
Q

what’s the use and position of fuel oil?

A

5
fuel for ships

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9
Q

what’s the use and position of bitumen?

A

6 - highest/ last
making roads

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10
Q

what part is the hottest and coldest part of the fractional distillation?

A

hotter at bottom
colder at top

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11
Q

how does fractional distillation work?

A
  1. heated crude oil vapours enter the column
  2. vapours rise until they reach their boiling point where they condense
  3. different vapours condense at different heights due to their different boiling points
  4. similar vapours condense together as a fraction
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12
Q

what is the order of fraction from low BP to high BP?

A

refinery gases
gasoline
kerosene
diesel
fuel oil
bitumen

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13
Q

what are alkanes?

A

hydrocarbons made of molecules C & H held together by covalent bonds

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14
Q

what is the general formula for alkanes?

A

C(n)H(2n+2)

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15
Q

what is the formula for methane?

A

CH4

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16
Q

what is the formula for ethane?

A

C2H6

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17
Q

what is the formula for propane?

A

C3H8

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18
Q

what is the formula for butane?

A

C4H10

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19
Q

what is the formula for pentane?

A

C5H12

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20
Q

what’s the structural formula for butane?

A

CH3 CH2 CH2 CH3

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21
Q

what’s the empirical formula for butane?

A

C2H5

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22
Q

alkanes are a …

A

homologous series of organic molecules

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23
Q

why are alkanes a homologous series?

A

as they have similar chemical reactions, trends in physical properties, same general formula

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24
Q

what are isomerism with alkanes?

A

isomers are the same molecular formula just different structural formula

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25
what are the two types of combustion alkanes undergo?
complete combustion incomplete combustion - dependant on oxygen availability
26
what is a complete combustion?
when there is excess oxygen alkane + oxygen > carbon dioxide + water
27
what is an incomplete combustion?
when there isn't enough oxygen instead of forming CO2, CO is formed (a toxic gas which lowers oxygen capacity for carrying blood) and also C soot - causing lung dieases releases less energy
28
what type of gases are formed when there is an incomplete combustion of alkanes/alkenes?
CO (a toxic gas which lowers oxygen capacity for carrying blood) and also C soot - causing lung diseases
29
what are the three significant pollutants released via the combustion of alkanes/alkenes?
CO2 - carbon dioxide NOx - nitrogen oxides SO2 - sulphur dioxide
30
pollutants released via the combustion of alkanes/alkenes: CO2 carbon dioxide
greenhouse gas traps heat in atmosphere and causes climate change
31
pollutants released via the combustion of alkanes/alkenes: NOx nitrogen oxides
formed when nitrogen from the air combusts - usually from really, really hot car engines which dissolve in rainwater to form acid rain, corroding structures and hurting plants and aquatic life
32
pollutants released via the combustion of alkanes/alkenes: SO2 sulphur dioxide
forms when sulphur impurities in fuel combust dissolves in rainwater to make acid rain
33
what happens when alkane reaction with halogens?
substitution reaction requires uv light swap a hydrogen atom for a halogen atom works with any alkane or halogen methane + bromine > bromomethane + hydrogen bromide CH4 + Br2 > CH3Br + HBr
34
what are the two things you need to know about the reaction of a halogen with an alkane?
substitution reaction - H swaps with halogen requires uv light - alkane is quite unreactive
35
what is the difficulty about alkanes and crude oil?
crude oil contains much longer alkanes than shorter ones, but the shorter ones are more useful therefore we take the longer alkanes and do cracking breaking down the longer alkanes into smaller more useful ones
36
what are the conditions for cracking?
temperature: 650 degrees catalyst: aluminum oxide (Al2O3)
37
what does cracking produce?
long alkane> shorter alkane + alkene
38
what are alkenes?
hydrocarbons that had ONE double c=c bond in their carbon chain
39
what are alkenes general formula?
C(n)H(2n)
40
what is the formula for ethene?
C2H4
41
what is the formula for propene?
C3H6
42
what is the formula for butene?
C4H8
43
what is the formula for pentene?
C5H10
44
what is the structural formula for butene?
CH2=CH CH2 CH3
45
alkenes are a ...
homologous series of organic molecules: similar chemical reaction trends in physical properties same general formula
46
alkenes are referred as unsaturated because ...
they have a double C=C bond
47
alkanes are referred as saturated because ...
they DON'T have a double C=C bond
48
what happens when alkenes react with bromine?
react and the C=C bond breaks adding bromine atoms in ethene + bromine > dibromoethane C2H4 + Br2 > C2H4Br2
49
what type of reaction is bromine with alkenes?
addition reaction - adding bromine atoms to the alkene happens without uv light - alkenes more reactive than alkanes works with pure bromine liquid or bromine water (ORANGE) mixture turns orange to colourless as bromine is used up in reaction the c=c bond is broken so that the Br can be added
50
what is the colour change in a bromine and alkene reaction?
orange to colourless
51
what can you test for using a bromine and alkene reaction?
test for the C=C unsaturated compound
52
what are additional polymers?
forms when molecules with C=C bond adds into chains
53
what are monomers?
small molecules that add together
54
what are polymers?
long chain they form when added to monomers
55
how to represent addition polymer?
-(-c-c-)-n n represents the repeats in the polymer chain
56
what is the use of polyethene?
drinks bottles shopping bags
57
what is the use of polypropene?
storage boxes climbing ropes
58
what is the use of polychloroethene?
wire insulation drain pipes
59
what is the use of polytetrafluoroethene?
non stick coating
60
what are the disposal issues of polymers?
they are inert (very unreactive) don't break down easily: reuse it recycle it incinerate it chuck it into landfill

gsce chemistry (21 decks)

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