1
Q
what happens as the boiling points of the fractions increase?
A
- the fractions get darker in colour
- the fractions get more viscous
2
Q
what’s the use for refinery gases?
A
fuel for home cooking & home heating
3
Q
what’s the use for gasoline?
A
fuel for cars
4
Q
use for kerosene?
A
fuel for aircraft & industrial heating
5
Q
use for diesel?
A
fuel for trains, trucks, some cars
6
Q
use for fuel oil?
A
fuel for ships
7
Q
use for bitumen?
A
making roads/roofs
8
Q
list the fractions in order of BP from low —> high
A
- refinery gases
- gasoline
- kerosene
- diesel
- fuel oil
- bitumen
9
Q
list the fractions in order of molecular mass, from low —> high
A
- refinery gases
- gasoline
- kerosene
- diesel
- fuel oil
- bitumen
10
Q
list the fractions in order of colour from light —> dark
A
- refinery gases
- gasoline
- kerosene
- diesel
- fuel oil
- bitumen
11
Q
list the fractions in order of viscosity from low —> high
A
- refinery gases
- gasoline
- kerosene
- diesel
- fuel oil
- bitumen
12
Q
define crude oil or something idk just info about crude oil
A
crude oil is a mixture of hydrocarbons; the different hydrocarbons in crude oil come in huge variety of shapes & sizes
this results in crude oil boiling over very large range of temps
13
Q
each fraction of crude oil is a mixture of….
A
similar hydrocarbons with similar BPs
14
Q
describe the process of fractional distillation
A
- heated crude oil vapours enter the column
- vapours rise until they reach their BP, when they condense
- diff. vapours condense at diff. heights due to their diff. BPs
- similar vapours condense together as a fraction due to similar BPs
15
Q
definition of alkanes?
A
alkanes are a homologous series of hydrocarbons that fit the general formula CnH2n+2
they’re made of simple molecules containing C & H atoms held together by covalent bonds
16
Q
what is the name of CH4?
A
methane
17
Q
what is the name of C2H6?
A
ethane
18
Q
what’s the name of C3H8?
A
propane
19
Q
what’s the name of C4H10?
A
butane
20
Q
what’s the name of C5H12?
A
pentane
21
Q
what’s the formula for methane?
A
CH4
22
Q
formula for ethane?
A
C2H6
23
Q
formula for propane?
A
C3H8
24
Q
formula for butane?
A
C4H10
25
formula for pentane?
C5H12
26
what does structural formula do/look like?
this shows the structure of the molecule **in one line**, read from left to right **like a word**:
CH3CH2CH2CH3
27
what does the term homologous series mean?
that they are a **family** of molecules which have:
- **similar chemical** reactions
- **trends in physical** properties (e.g. BPs, viscosity, colour)
- the **same general** formula
28
definition of isomers?
isomers are molecules with the **same molecular formula** but **different structural formula**
29
most alkanes are used as _____ because they _______ _ ___ __ ______ when _________
most alkanes are used as **fuels** because they **release a lot of energy** when **combusted**
30
when does complete combustion occur, and whats the word equation for it?
- when there’s excess oxygen
- alkane + oxygen —> carbon dioxide + water
31
when does incomplete combustion occur, and what are the products?
- when there’s not enough oxygen
- mixture of CO (toxic gas which bins to haemoglobin & prevents oxygen transport in the blood) & soot (C) which causes lung diseases
it also releases **less** energy, so it makes the alkane less useful as a fuel
32
what are the three significant pollutants which the combustion of alkanes as fuel release into the atmosphere?
- CO2
- nitrogen oxides (NOx)
- SO2
33
what does carbon dioxide do and how is it formed in the combustion of alkanes as fuel?
- is a **greenhouse gas** that traps heat in atmosphere & **causes climate change**
- forms directly from combustion of the alkane fuel
34
what do nitrogen oxides do and how are they formed in the combustion of alkanes as fuel?
- **dissolve** in rainwater to form **acid rain**, which corrodes structures & is harmful to plant & aquatic life
- form when **nitrogen from air combusts**. usually doesn’t combust but car engines are extremely hot
35
what does sulphur dioxide do and how is it formed in the combustion of alkanes as fuel?
- like NOx, also dissolves in rainwater to form **acid rain**
- forms when **sulphur impurities in fuel combust**
36
alkanes react with halogens by ________ one ________ atom for one _______ atom
alkanes react with halogens by **swapping** one **hydrogen** atom for one **halogen** atom
37
what happens when ethane reacts with bromine?
**substitution reaction**:
one H in ethane swaps with one Br in bromine, and so you end up with
C2H6 + Br2 —> C2H5Br + HBr
(this reaction would work with **any alkane** and **any halogen**)
38
true or false: substitution reactions cannot work with any alkane and any halogen
false - all that happens is a hydrogen swaps with a halogen
39
what condition does a substitution reaction require?
UV light, because it provides energy (the alkane is quite unreactive)
40
what does cracking do?
it breaks down longer alkanes into smaller, more useful ones
41
what conditions does cracking need?
temp = 650°C, and a catalyst of aluminium oxide (Al2O3)
—> can be conducted without catalyst but far more energy would need to be provided
42
what is the general equation for cracking?
long alkane —> shorter alkane + alkene
43
anything is possible with cracking, as long as it makes an ______ and an ______, & the numbers of _ and _ atoms ___ __
anything is possible with cracking, as long as it makes an **alkane** and an **alkene**, & the numbers of **C** and **H** atoms **add up**
44
definition of an alkene?
alkenes are a homologous group of **hydrocarbons** that fit the **general formula CnH2n**
45
what is the difference between alkanes and alkenes?
alkanes = **no** C=C double bond in carbon chain —> **saturated**
alkenes = **has** C=C double bond in carbon chain —> **unsaturated**
46
what’s the name of C2H4?
ethene
47
what’s the name of C3H6?
propene
48
what’s the name of C4H8?
butene
49
what’s the name of C5H10?
pentene
50
molecular formula for ethene?
C2H4
51
molecular formula for propene?
C3H6
52
molecular formula for butene?
C4H8
53
molecular formula for pentene?
C5H10
54
how is the double bond sometimes shown in a structural formula?
with a ‘=‘ e.g. butene is written as
CH2=CHCH2CH3
55
what are the two ways that isomers for alkenes can differ?
1. branching of carbon chain
2. position of the C=C in carbon chain
56
what do saturated/unsaturated mean?
saturated = **no** C=C double bond (alkanes)
unsaturated = **yes** C=C double bond (alkenes)
57
true or false: alkenes can also combust completely & incompletely in oxygen to release energy
true
58
what happens when alkenes react with bromine?
the C=C double bond is broken and the bromine atoms are added in
e.g.:
H H H H
| | | |
H - C = C - H + Br —> H - C - C - H
| |
Br Br
or C2H4 + Br2 —> C2H4Br2
- it’s an **addition** reaction
- happens **without UV light** (alkanes more reactive than alkenes)
- works w **pure Br liquid** or **Br water (orange**)
- *orange —> colourless* (Br used up in reaction)
59
what type of reaction is it when alkenes react with bromine?
addition reaction
60
true or false: the reaction between alkenes and bromine requires UV light
false - alkenes more reactive than alkanes, so don’t need extra energy
61
what liquids does the reaction between alkenes and bromine work with?
either pure bromine liquid or bromine water (which is orange)
62
what’s the colour change in the reaction with alkenes and bromine?
orange —> colourless (Br used up in reaction)
63
what’s the reaction between alkenes and bromine used to test for?
used as a test for the C=C in unsaturated compounds:
- stays orange = no C=C (saturated)
- turns colourless = yes C=C (unsaturated)
64
when does an addition polymer form/what is it?
an addition polymer forms when molecules with a C=C double bond **add into chains**
65
what are the small molecules that add together called? (addition polymers)
monomers
66
what’s the long chain that monomers form when added together called?
a polymer
67
how do the names of addition polymers work?
by putting ‘poly’ in front of the monomer name, e.g. polymer formed by **ethene** would be **poly(ethene)**
68
what does polyethene look like as a monomer and repeating unit?
monomer:
H H
| |
C=C
| |
H H
repeating unit:
H H
| |
—(— C - C —)—
| | n
H H
69
what does polypropene look like as a monomer and a repeating unit?
monomer:
CH3 H
| |
C = C
| |
H H
repeating unit:
CH3 H
| |
—(— C - C —)—
| | n
H H
70
what does poly(chloroethene) look like as a monomer & repeating unit?
monomer:
Cl H
| |
C=C
| |
H H
repeating unit:
Cl H
| |
—(— C - C —)—
| | n
H H
71
what does poly(tetrafluroethene) look like as a monomer and repeating unit?
monomer:
F F
| |
C=C
| |
F F
repeating unit:
F F
| |
—(— C - C —)—
| | n
F F
72
what are the uses for polyethene?
- drinks bottles
- shopping bags
73
what are the uses for polypropene?
- storage boxes
- climbing ropes
74
what are the uses for poly(chloroethene)?
- wire insulation
- drainpipes
75
what is the use for poly(tetrafluoroethene)?
non-stick coating
76
why is it difficult to dispose of addition polymers?
- they’re **inert**: chemically **very unreactive**
- this means that they **don’t break down easily**
77
what are the ways to dispose of addition polymers?
1. reuse it
2. recycle it
3. incinerate it; use energy released to generate electricity
4. put it into landfill
78
what are the complete combustion product formulae for alkanes and alkenes?
CO2 + H2O
79
what are the incomplete combustion product formulae for alkanes & alkenes?
mixture: C, CO, CO2, H2O
chemistry
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