Hydrocarbons and Fuels Flashcards
1
Q
saturated hydrocarbons
A
compounds where there are only C-C single bonds between the C atoms in the molecule
2
Q
unsaturated hydrocarbons
A
compounds where there is one or more double or triple C-C bond in the molecule
3
Q
homologous series
A
a series of compounds with similar chemical properties
have graduations in physical properties
same general formula for its members
each member has a similar method of preparation
each member differs from the previous member by a CH2 unit
4
Q
what is a homologous series another name for
A
a family of organic compounds
5
Q
what is the system used to name compounds
A
the IUPAC system
6
Q
what is the prefix for 1 C
A
meth
7
Q
what is the prefix for 2 C
A
eth
8
Q
what is the prefix for 3 C
A
prop
9
Q
what is the prefix for 4 C
A
but
10
Q
what is the prefix for 5 C
A
pent
11
Q
what is the prefix for 6 C
A
hex
12
Q
what is the prefix for 7 C
A
hept
13
Q
what is the prefix for 8 C
A
oct
14
Q
what is the prefix for 9 C
A
non
15
Q
what is the prefix for 10 C
A
dec
16
Q
are alkanes unsaturated or saturated
A
saturated
17
Q
what do alkanes end in
A
ane
18
Q
what is the general formula of an alkane
A
CnH2n+2
19
Q
what is a chloroalkane
A
an alkane where 1 or more H atoms have been replaced by chlorine atoms
20
Q
are chloroalkanes soluable in water
A
no - non polar
21
Q
do chloro alkanes have a higher or lower boiling point than alkanes
A
higher
atoms with a larger electron density have stronger van der waals
more energy is needed to over come this force of attraction
22
Q
structural isomers
A
compounds with the same molecular formula but different structural formula
23
Q
what are the 2 side groups
A
methyl and ethyl
24
Q
when are you able to have an ethyl side group?
A
when there are 7 or more C in the central chain
has to be more than 3 carbons from the end
25
what is a methyl side group
CH3
26
what state are chloroalkanes at room temp
liquid
27
what is an ethyl side group
C2H5
28
where can you put a side group?
methyl- cant be on either end
ethyl has to be atleast 3 carbons away from either end
29
how do you name a compound with a side group
state what number carbon the side group is on. (do this for every side group on the compound
state side group. side groups are listed alphabetically
if there is more than one side group but di or tri
and then name the carbon chain and whether it is an alkane, alkene or alkyne
30
do saturated hydrocarbons react with H2?
they do not partake in addition reactions with h2
31
how do you number the carbons
start numbering from the side where the side group is present with the lowest number
32
does boiling point increase or decrease with chain length
increases
33
why does boiling point increase with longer chain length
longer chain molecules have a larger electron density
this gives rise to stronger van der waals between hydrocarbon molecules as temporary dipoles form more easily
more energy is needed to over come these interactions
thus bp is higher
34
are alkenes saturated or unsaturated
unsaturated due to the double bond
35
what do alkenes end in
ene
36
general formula of alkenes
CnH2n
37
how to name an alkene
you must reference where the double bond is.
number your carbons, whichever side the double bond is closer to one is the position of the double bond. name it inbetween the but and ene so it would be but-1-ene
38
what shape are carbons in alkanes
tetrahedral
39
what shape are carbons in alkenes
trrigonal planar
40
what shape are carbons in alkynes
linear
41
what type of reaction is involved in the preparation of ethene
elimination (dehydration)
42
uses of ethene
ripening of fruit
43
what is ethene
a colourless gas that smells sweet
44
what is the test for unsaturation
add bromine water and shake
if the bromine water changed from red to colourless unsaturation is present
or
add acidified potassium permanganate
unsaturation is present if there is a colour change from purple to colourless
45
what type of reaction are the tests for unsaturation
adititon reactions
46
write the balanced equation for the bromine test for unsaturation
ethene + bromine ---->1,2-dibromoethane
47
what does ethene burn as
a luminous yellow flame
48
what are alkynes
compound where there is a c-c triple bond
49
what doe an alkyne end in
yne
50
general formula of an alkyne
CnH2n-2
51
what is the only alkyne you need to know
ethyne
52
what is ethyne used in
welding tourches
53
what type of reaction is the preparation of ethyne
substitution reaction
54
what is ethyne
a sweet smelling gas that is insoluable in water
55
what does ethyne burn as
a smoky yellow flame
56
aliphatic compound
an organic compound that consists of open chains of carbon atoms and closed chain compounds that resemble them in chemical properties
57
aromatic compounds
compounds that contain a benzene ring or structure in their molecules
58
is benzene polar or non polar
non polar
59
properties of benzene
liquid at room temp
highly toxic
not soluable in water
60
why is benzene unreactive?
the 3 pi e- thst form the double bonds are delocalised over all 6 C atoms providing extra stability
61
why doesnt benzene cause bromine water to change colour even though it is unsaturated?
it is not reactive enough due to delocalisation of e-
62
what is the bond length in benzene
all c-c bond lengths are the same due to delocalisation of e-
the bond lengths are somewhere between a double a single bond
63
what dimension is benzen
planar 2D
64
what are the bond angles in benzene
120 between c atoms
65
how many sigma electrons are there in benzene
3 on each c atom
66
how many pi e- are there in benzene
6
67
what is delocalisation
electrons are not fixed on one atom
68
octane number
measure of the ability of a fuel to resist knocking/ auto-ignition
69
auto ignition/ knocking
when the petrol air mixture ignites prematurely in a combustion engine
70
is it better to have a high or low octane number
high
71
which fuel has an octane number of 100
2,2,4- trimethyl-pentane
72
which fuel has an octane number of 0
heptane
73
what is 2,2,4 trimethyl-pentane's octane number
100
74
what is heptanes octane number
0
75
what does it mean if a fuel has an octane number of 90?
it is as efficient as a fuel with a mixture of 90% 2,2,4 trimethyl-pentane and 10% heptane
76
what are the factors that effect octane number
length of the hydrocarbon chain
degree of branching
cyclic or straight chain
77
is it better to have a short or long chain length in relation to octane number
the shorter the chain the higher the octane number is
78
is it better to have a high or low degree of branching in relation to octane number
high
79
is it better to have a cyclic or straight chain in relation to octane number
cyclic chain = higher octane number
80
why is lead no longer added to petrol?
it is toxic
it poisons the catalyst in the catalytic converter
81
why was lead historically added to fuel
to increase octane number
82
what are the ways of increasing octane number
isomerisation
catalytic cracking
dehydrocyclisation
adding oxygenates to fuel
83
what is isomerisation
adding branches to straight alkane chains
84
what alkanes are commonly involved in isomerisation in an oil refinery
heptane and pentane
85
how to identify isomerisation from a balanced equation
the starting material has the same molecular formula as the product
the chain is shorter and has a higher degree of branching in the product
86
catalytic cracking
breaking up of long chain hydrocarbons into shorter, more in demand hydrocarbons using heat and a catalyst
87
how to identify catalytic cracking
starting with one long molecule and ending up with 2 shorter ones
one of the products is unsaturated (has a double bond)
88
benefits of catalytic cracking
makes shorter chain more in demand hydrocarbons available
alkenes produced are used as feedstock for petrochemical industry
89
what is dehydrocyclisation
use of catalysts to form ring/cyclic compounds
90
what is produced from dehydrocyclisation
hydrogen
91
how to identify dehydrocyclisation
a straight chain molecule forms a cyclic molecule and hydrogen is produced
92
what is an oxygenate
a compound that contains oxygen
93
what are 3 examples of oxygenates added to fuel to increase octane number
methanol, ethanol, MTBE
94
what does MTBE stand for
methyl-tertiary-butyl-ether
95
what are the benefits of adding oxygenates to fuel
increases octane number
makes fuel burn more cleanly
96
will a compound with a high or low octane no be more likely to autoignite
low
97
give some uses of hydrogen
fuel
ammonia production
manufacturing of margarine
98
why is H a good fuel?
it burns cleanly- no greenhouse gases are released during combustion as water is the only product
it has a high kilogram calorific value
it has a high octane number
99
what are the 2 methods of producing H for industry
steam reformation of natural gas
electrolysis of water
100
what is steam reformation of natural gas
methane is reacted with steam over a suitable catalyst
101
what is the balanced equation for steam reformation of natural gas
CH4 + H2O ----> 3H2 + CO
102
what is electrolysis of water?
passing electricity through water using platinum electrodes and water is split into hydrogen and oxygen gas
103
write a balanced equation for electrolysis of water
H2O ---> H2 + 1/2 O2
104
why does elemental H not occur in nature on earth as a fuel source
its explosive
105
what is crude oil
a fossil fuel composed of a mixture of hydrocarbons and is one of the most useful materials on earth
106
what is crude oil used for
it is a feedstock for the plastics industry
pharmacuticals
107
what is fractional distillation
it separates crude oil into a number of different more useful fractions according to their different boiling points (chain length)
108
which hydrocarbons are at the top of the column
C1- 4
(smaller chain hydrocarbons)
109
why are mercaptans added to fuels?
to give them a smell so that gas leaks can be detected
110
what are mercaptans
sulphur compounds added to fuel to give them a smell so that gas leaks can be detected
111
describe how fractional distillation separates the different fractions in crude oil
->different fractions separate according to their different boiling points
->crude oil is pumped in at the bottom. a furnace is used to heat the crude oil and most fractions are vaporised and enter the tower
-> there is a temperature gradient in the tower - hotter at the bottom and colder at the top. the vaporised fractions travel up through the tower the substance with the highest boiling point emerge at the bottom of the tower (longest chain)
->bubble caps have small holes to slow down the rate the vapor rises. fractions condense at their boiling point and are collected in the trays and removed through outlets
112
draw a diagram of fractional distillation
113
what is refinery gas used for
domestic heating/cooking
114
what is petrol used for
fuel for cars
115
what is naphtha used for
feedstock for petrochemicals
116
what is kerosine used for
fuel for aircraft
117
what is diesel oil used for
fuels for buses trucks or trains
118
use of lubricating oil
waxes and polishes
119
use of fuel oil
fuel for ships
120
use of bitumen
tar for roads and roofing
121
hydrocarbon
a compound that contains only carbon and hydrogen atoms
122
alkenes
a hydrocarbon with atleast 1 double c-c bond
