Organic Chemistry Flashcards
1
Q
What is crude oil?
A
A mixture of hydrocarbons
2
Q
What are hydrocarbons?
A
Mixtures made of covalently bonded hydrogen and carbon molecules
3
Q
Why is crude oil a mixture?
A
The compounds aren’t chemically bonded together and are therefore easily separated
4
Q
What is an alkane?
A
A family of hydrocarbons
5
Q
What are the first four members of the alkanes?
A
Methane CH4
Ethane C2H6
Propane C3H8
Butane C4H10
6
Q
What is a substance when it is described as having saturated bonds?
A
A substance that has no double bond
7
Q
What is a homologous series?
A
A group of compounds that can all be represented by the same general formula
8
Q
What is the general formula for alkanes?
A
Cn H2n+2
9
Q
What is an isomer?
A
Two molecules that have identical molecular formulas but different structures
10
Q
What are the isomers of butane?
A
Butane
2-Methyl propane
11
Q
What different properties do isomers have compared to alkanes?
A
Lower boiling points because branching makes the molecule more compact and therefore decreases its SA. As a result, the inter molecular forces decrease as they depend on the SA.
12
Q
What is the formula for complete combustion of alkanes?
A
Alkane + oxygen —> carbon dioxide + water
13
Q
What happens when complete combustion of an alkane happens?
A
Lots of energy is released and the gas burns with a clear blue flame
14
Q
What is the formula for incomplete combustion of an alkane?
A
Alkane + oxygen —> carbon + carbon monoxide + carbon dioxide + water
15
Q
What happens when incomplete combustion of an alkane occurs?
A
Less energy is released and it isn’t safe because CO is poisonous. The gas burns with a smoky orange flame.
16
Q
What is formed when a halogen reacts with an alkane?
A
Haloalkanes are formed
17
Q
What conditions are required for a haloalkane to form?
A
UV light
18
Q
What is the equation for methane and bromine reacting together?
A
Methane + bromine –> bromomethane + hydrogen bromide
CH4 + Br2 –> CH3Br + HBr
19
Q
What kind of reaction occurs when a halogen reacts with an alkane?
A
A substitution reaction
20
Q
What is the test for an alkane?
A
Alkane + bromine water —> remains orange
21
Q
What is an alkene?
A
Hydrocarbons that have a double bond between two of the carbon atoms in their chain.
22
Q
What is meant by an unsaturated molecule?
A
A molecule that has a double bond, so they’re more reactive than alkanes
23
Q
What are the first three members of the alkenes?
A
Ethene C2H4
Propene C3H6
Butene C4H8
24
Q
What is the general formula for the alkenes?
A
Cn H2n
25
What are the isomers of butene?
Butene
But-2-ene
2methylpropene
26
What is the test for alkenes?
Alkene + bromine water --> goes from orange to colourless
27
What happens when a halogen reacts with an alkene?
They form haloalkenes
28
What is the equation for ethene + bromine?
Ethene + bromine --> dibromoethane
| C2H4 + Br2 --> C2H4Br2
29
What happens when ethene and bromine react together?
The C C double bond is split and a bromine atom is added to each of the carbons, so it is called an addition reaction.
30
What is the general formula for alcohols?
Cn H2n+1 OH
31
What are the first three members of the alcohols?
Methanol CH3 OH CH4O
Ethanol CH3 CH2 OH C2H6O
Propanol CH3 CH2 CH2 OH C3H8O
32
What are the isomers of butanol?
Butanol
Butan-2-ol
2-methyl propan-1-ol
2-methyl propan-2-ol
33
What are the two methods used to produce ethanol?
Fermentation
| Hydration of ethene
34
What is the process of fermentation?
Yeast is added to a sugar/starch solution
It's left in the warm (30-40°C) in anaerobic conditions
Enzymes in the yeast convert the sugar into ethanol and CO2
35
What is the equation for fermentation?
Sucrose + water --> glucose
C12H22O11 + H2O --> 2C6H12O6
Glucose --> ethanol + carbon dioxide
C6H12O6 --> 2C2H5OH + 2CO2
36
What are the raw materials and what type are they needed for fermentation?
Glucose from plants (renewable)
37
What are the conditions needed for fermentation?
Warm (30-40°C)
Normal pressure (1 atm)
Enzymes in yeast acting as a catalyst
38
What are the energy costs of fermentation?
Little
39
What type of process is fermentation?
A batch process
| Inefficient because it isn't continuous
40
What is the reaction rate of fermentation?
Very slow
41
Is the ethanol produced by fermentation pure?
No it's impure so needs further treatment
42
What are the advantages of fermentation?
Uses a renewable resource
Doesn't release harmful gases into the atmosphere
It's a batch process, so it can stop and start whenever
Little energy is required so there are lower energy costs
43
What are the disadvantages of fermentation?
```
Production costs are high
Lots of workers are needed
Production is slow
The product is impure so it needs further treatment
Releases CO2
```
44
What is the process of hydration of ethene?
Ethanol is produced when ethene reacts with steam
45
What are the raw materials and what type are they needed for hydration of ethene?
Ethene from crude oil
| Non renewable
46
What conditions are needed for the hydration of ethene?
```
High temp (300°C)
High pressure (60-70 atm)
Phosphoric acid used as a catalyst
```
47
What type of process is the hydration of ethene?
A continuous flow system which is efficient because a stream of reactants is passed continuously over a catalyst
48
What are the energy costs of the hydration of ethene?
Higher than fermentation
49
What is the reaction rate of the hydration of ethene?
Very fast
50
How pure is the ethanol produced by the hydration of ethene?
Pure
51
What are the advantages of the hydration of ethene?
Production is fast and continuous
Few workers are required so it's a cheaper process
The product is pure
52
What are the disadvantages of hydration of ethene?
It uses non renewable resource
| Lots of energy, high temps and high pressures are needed so it's more expensive
53
What is the overall equation for the hydration of ethene?
Ethene + steam --> ethanol
| C2H4 + H2O --> C2H5OH
54
What are the uses for ethanol?
```
Alcoholic drinks
Biofuel
Solvent in the manufacture of varnishes and perfumes
Preparation of flavourings
Disinfectant
```
55
What is the process by which ethanol can be turned into ethene?
The dehydration of ethanol which is the removal of water from the ethanol, so it's a dehydration reaction
56
What is the process of the dehydration of ethanol?
Ethanol vapour is passed over hot aluminium oxide which is acting as a catalyst. The OH- group is then removed from the ethanol along with a hydrogen atom.
57
What is the equation for the dehydration of ethanol?
Ethanol --> ethene + water
| C2H5OH --> C2H4 + H2O
58
What is a polymer?
A long chain molecule made from lots of small molecules (monomers) joined together
59
What is a monomer?
Small molecules that join together to make polymers
60
What is polymerisation?
The formation of long chain molecules from lots of small molecules joining together
61
What are the two types of polymerisation?
Addition polymerisation
| Condensation polymerisation
62
When does addition polymerisation occur?
When the same monomers containing carbon carbon double bonds join together to produce a very long chain
63
What kind of monomers does addition polymerisation require?
Unsaturated monomers (alkenes) because during the reaction the double bond breaks open. The spare electrons are used to make bonds between the different monomers
64
What are the conditions needed for addition polymerisation?
High pressure
High temperature
Catalyst
65
What are the uses for poly(ethene)?
Low density poly(ethene) = not so strong and flexible so plastic bags
High density poly(ethene) = stronger and more rigid so plastic bottles
66
What are the uses for poly(propene)?
Ropes and crates because it's stronger than poly(ethene)
67
What are the uses for poly(chloroethene)?
Drain pipes, window frames and electrical insulation because it's strong and rigid and doesn't conduct electricity
68
When does condensation polymerisation occur?
When two different monomers join together alternately. Each time the two monomers join together a new molecule is lost.
69
What two monomers are required to create nylon?
```
Diamine = compound with an amine group at either end of the molecule
Dicarboxylic = compound sign an acid group at either and of the molecule
```
70
What is the displayed formula for the two monomers needed to make nylon?
Diaminohexane (diamine) Hexanedioic acid (dicarboxylic acid)
O O
H H || ||
H-N- C6H12 -N-H + OH-C- C4H8 -C-OH
71
What can the OH- ions in the hexanedioic acid be replaced by to bring down the temperature needed for the production of acid on an industrial scale?
Cl atoms
72
What is the process of fractional distillation?
Crude oil is heated until it is vapourised
The gases enter a fractionating column
Bitumen is drained off at the bottom
There is a temperature gradient in the fractionating column (hot at bottom (400°C) cold at top (150°C))
When the gases reach the part of the column where the temp is lower than their boiling point, they condense.
Longer hydrocarbons = high boiling points, so they condense and drain out of the column early when they're near the bottom
Shorter hydrocarbons = low boiling points, so they turn liquid and drain out later on near the top of the column where it's cooler
Bubble caps in the fractionating column stop the separated liquids from running back down the column and mixing.
End result = crude oil mixture is separated into different fractions. Each fraction contains a mixture of hydrocarbons with similar boiling points
73
What are the fractions that crude oil is separated into and what are their uses?
Refinery gases = bottled gas, heating, pottery and glass manufacture
Gasoline = fuel for cars
Naphtha = starting material to make plastics, dyes, explosives and paints
Kerosene = jet engines, domestic heating and paint solvent
Diesel = fuel for Diesel engines in cars, trucks, trains and boats
Fuel Oil = domestic central heating, fuel for big ships
Bitumen = road surfacing and asphalt for roofs
74
Why is fractional distillation a physical process?
No chemical reactions occur
75
What are the properties of the smaller chain alkanes in the fractions as the temp increases?
Flammability = decreases because IM forces are stronger as the length of the chain increases
Viscosity = increases
Boiling Point = increases because IM forces are stronger so more energy is needed to break them
Volatility = decreases because IM forces are stronger so it's thicker
Colour = gets darker
No of carbons in chain = increases
76
What does viscosity mean?
How gloopy/thick a substance is
77
What does volatility mean?
How easily something turns from a liquid to a gas
78
At what temperature is the yeast poisoned by its own excretion product during fermentation?
14%
79
How is strong alcohol made?
By distillation
80
What is the test for ethanol?
Try to ignite the vapour produced by distillation with a match
81
What is the sequence of events for crude oil to ethanol?
```
Crude oil extracted
Fractional distillation
Cracking
Hydration
Ethanol is produced
```
82
Why are the alkanes cracked after fractional distillation?
Long hydrocarbons have high boiling points and are viscous
| There is a higher demand for shorter hydrocarbons like octane because they are more useful
83
What is the process of cracking?
Long chain hydrocarbons are broken down into simpler molecules by heating them (thermal decomposition).
84
What does cracking produce?
A shorter chain alkane and two alkenes
85
What conditions are needed for cracking?
Heat (600-700°C)
| A powdered catalyst (silica (SiO2) and alumina (Al2O3))
86
Describe the process of cracking
Mineral wool soaked in paraffin is heated for a few seconds, then the catalyst is heated for a few seconds.
Continue until the paraffin is vapourised and the catalyst glows red.
The heated paraffin vapour cracks as it passes over the heated catalyst.
Small alkenes collect at the end of the boiling tube.
Alkane gases travel down the delivery tube.
The alkenes are then collected through water using a glass jar.
87
Why is CO poisonous?
It combines with haemoglobin in the RBCs, so they can't carry as much oxygen. This can result in fainting, coma or death.
