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gsce chemistry > organics 4.5 > Flashcards

organics 4.5 Flashcards

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
Q

what are the two types of combustion alkanes undergo?

A

complete combustion
incomplete combustion
- dependant on oxygen availability

26
Q

what is a complete combustion?

A

when there is excess oxygen

alkane + oxygen > carbon dioxide + water

27
Q

what is an incomplete combustion?

A

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
Q

what type of gases are formed when there is an incomplete combustion of alkanes/alkenes?

A

CO (a toxic gas which lowers oxygen capacity for carrying blood) and also C soot - causing lung diseases

29
Q

what are the three significant pollutants released via the combustion of alkanes/alkenes?

A

CO2 - carbon dioxide
NOx - nitrogen oxides
SO2 - sulphur dioxide

30
Q

pollutants released via the combustion of alkanes/alkenes:
CO2 carbon dioxide

A

greenhouse gas traps heat in atmosphere and causes climate change

31
Q

pollutants released via the combustion of alkanes/alkenes:
NOx nitrogen oxides

A

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
Q

pollutants released via the combustion of alkanes/alkenes:
SO2 sulphur dioxide

A

forms when sulphur impurities in fuel combust
dissolves in rainwater to make acid rain

33
Q

what happens when alkane reaction with halogens?

A

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
Q

what are the two things you need to know about the reaction of a halogen with an alkane?

A

substitution reaction - H swaps with halogen
requires uv light - alkane is quite unreactive

35
Q

what is the difficulty about alkanes and crude oil?

A

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
Q

what are the conditions for cracking?

A

temperature: 650 degrees
catalyst: aluminum oxide (Al2O3)

37
Q

what does cracking produce?

A

long alkane> shorter alkane + alkene

38
Q

what are alkenes?

A

hydrocarbons that had ONE double c=c bond in their carbon chain

39
Q

what are alkenes general formula?

40
Q

what is the formula for ethene?

41
Q

what is the formula for propene?

42
Q

what is the formula for butene?

43
Q

what is the formula for pentene?

44
Q

what is the structural formula for butene?

A

CH2=CH CH2 CH3

45
Q

alkenes are a …

A

homologous series of organic molecules:
similar chemical reaction
trends in physical properties
same general formula

46
Q

alkenes are referred as unsaturated because …

A

they have a double C=C bond

47
Q

alkanes are referred as saturated because …

A

they DON’T have a double C=C bond

48
Q

what happens when alkenes react with bromine?

A

react and the C=C bond breaks adding bromine atoms in

ethene + bromine > dibromoethane
C2H4 + Br2 > C2H4Br2

49
Q

what type of reaction is bromine with alkenes?

A

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
Q

what is the colour change in a bromine and alkene reaction?

A

orange to colourless

51
Q

what can you test for using a bromine and alkene reaction?

A

test for the C=C unsaturated compound

52
Q

what are additional polymers?

A

forms when molecules with C=C bond adds into chains

53
Q

what are monomers?

A

small molecules that add together

54
Q

what are polymers?

A

long chain they form when added to monomers

55
Q

how to represent addition polymer?

A

-(-c-c-)-n
n represents the repeats in the polymer chain

56
Q

what is the use of polyethene?

A

drinks bottles
shopping bags

57
Q

what is the use of polypropene?

A

storage boxes
climbing ropes

58
Q

what is the use of polychloroethene?

A

wire insulation
drain pipes

59
Q

what is the use of polytetrafluoroethene?

A

non stick coating

60
Q

what are the disposal issues of polymers?

A

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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