Organic Chemistry Flashcards
(84 cards)
1
Q
Crude oil
A
A mixture of hydrocarbons that we use as a source of elements we use in society. It is a black tar-like liquid. There are thousands of hydrocarbons with different chain lengths.
2
Q
Background of crude oil
A
Crude oil formed from the decomposition of tiny creatures which lived in the sea more than 100 000 000 years ago. Certain conditions had to be present. The oil formed in porous sedimentary rocks that could hold the oil but an impermeable layer had to form on top to seal in the oil. Pressure on the rocks caused them to fold and form a dome under which oil could collect in sufficient quantities to be economical to extract.
3
Q
Coal
A
Black rock, from plants
4
Q
Hydrocarbons
A
Compounds made up of hydrogen and carbon only.
5
Q
What is crude oil?
A
A mixture of thousands of hydrocarbons, with different chain lengths
6
Q
How to separate crude oil into different products?
A
Physical processes such as fractional distillation
7
Q
Fossil fuels
A
Crude oil and natural gas (also a hydrocarbon) are classified as fossil fuels as they are formed from living things (fossil) and are burned to give energy (fuel).
8
Q
Alkanes
A
- most of the compounds in crude oil
- saturated hydrocarbons- meaning they contain only single covalent bonds
- these are fats
Eg. Ethane
9
Q
Draw ethane
A
N/a
10
Q
Unsaturated hydrocarbons
A
- alkenes
- have a double bond
Eg. Ethene
11
Q
Draw ethen
A
N/a
12
Q
What is the simplest hydrocarbon?
A
Methane (CH(4))
13
Q
Draw a dot and cross diagram of methane
A
N/a
14
Q
Draw the displayed formula of methane
A
N/a
15
Q
Limestone formation
A
Limestone was formed in the middle of the sea and is now found in the Peak District, nowhere near the coast, due to the split of Pangea.
16
Q
Homologous series
A
A series of compounds with similar structure, as a result of the joining together of carbon atoms into a chain.
17
Q
First six member of the alkane homologous series
A
Methane CH(4)
Ethane C(2)H(6)
Propane C(3)H(8)
Butane C(4)H(10)
Pentane C(5)H(12)
Hexane C(6)H(14)
18
Q
Draw the displayed formulas of the first six members of the homologous series
A
N/a
19
Q
Mnemonic for the first six members of the homologous series
A
Mice Eat Peanut Butter Pie Happily
20
Q
General formual of the homologous series
A
C(n)H(2n+2)
21
Q
In a homologous series, the compounds…
A
- Have the same general formula
- Contain the same functional group (this determines how the chemical reacts)
- Share similar chemical properties
- Follow a trend in physical properties
22
Q
Alkanes burn…
A
Well, giving out a lot of heat
23
Q
Isomers (NOT ISOTOPES)
A
Isomers are compounds that have the same molecular formula (eg. H(2)O, CH(4), etc.) but a different displayed formula.
24
Q
Molecular formula
A
Shows how many atoms of each element there are in a molecule
25
Displayed formula
Shows all the bonds between all of the atoms in a molecule
26
Draw Butane’s two popular isomers
N/a
27
Isomer rule
Even when you rotate or bend parts of the formula, they must look different. You cannot just bend a carbon atoms, etc.
28
Draw the 3 isomers of pentane
N/a
29
Draw the 5 isomers of hexane
N/a
30
Saturated hydrocarbons are what kind of fat?
Animal (eg. butter)
31
Unsaturated hydrocarbons are what kind of fat?
Plant (eg. oil, avocado)
32
Aldenyde
An aldehyde is a type of chemical made of:
• A carbon attached to:
• An oxygen (with a double bond),
• A hydrogen, and
• Another part, like a chain of atoms (called “R”).
You can think of it like this shape:
R–CHO
Formaldehyde is the simplest aldehyde. It’s used in cleaning products and science labs.
Aldehyde are found in flowers, fruits, perfumes and more.
33
What can crude oil be separated into?
Six smaller mixtures of hydrocarbons, called fractions. Within each fraction, there are similar sized hydrocarbons with similar boiling points.
34
How do you separate fractional distillation?
Fractional distillation (or other physical processes)
- using the different boiling point ranges of the fractions
- this us carried out in industry on a large scale
35
Draw the apparatus of fractional distillation
N/a
36
Describe how fractional distillation happens in oil and water
1. The oil mixture is heated and starts to evaporate
2. Vapour enters the fractionating column (this column is hot at the bottom but cool at the top)
3. At first, the vapour recondenses in the column and falls back into the flask
4. When the top of the column reaches the boiling point of the first fraction, it goes into the condenser, collecting in a conical flask
5. Fractions are collected at different temperatures in separate flasks
37
Testing oil fractions test
1. Note down the boiling point range of each fraction
2. Place 4 to 5 drops of one of the fractions on to a watch glass
3. Describe the appearance of the liquid (colour and viscosity)
4. With a splint, attempt to light the fraction
5. Describe the smokiness of any flame that is produced
6. Repeat steps 2 to 5 for the other fractions
38
Smaller chain molecules are…
Caught higher
39
Large chain molecules are…
Caught lower
40
Gasoline
Boiling point range: 80-120 °C
Colour: colourless
Ease of lighting: easily ignites
Smokiness of the flame: smoky
Viscosity: thin, runny
41
Fuel oil
Boiling point range: 175-300 °C
Colour: yellow
Ease of lighting: ignites
Smokiness of the flame: more smoky
Viscosity: thicker
42
Lubricating oil
Boiling point range: 300-600 °C
Colour: brown
Ease of lighting: doesn’t ignite
Smokiness of the flame: doesn’t ignite
Viscosity: thick
43
What is a fraction?
A mixture of hydrocarbons with similar sizes/boiling points.
44
As the boiling point of the fraction increases…
- the fraction gets darker in appearance
- the fraction is thicker/more viscous
- the flammability/ease of lighting decreases
- the smokiness of the flame decreases
45
As the number of carbons increases…
The boiling point increases
46
Crude oil is…
Unprocessed oil, found under the ground and sea
47
Explain why the alkanes get thicker and less runny as the length of carbon chains increases
Alkanes get more viscous as the carbon chain increases because longer carbon chains can become entangled with each other - resulting in a more viscous liquid.
48
If a chain is long…
The substance has a high boiling point, as it has stronger intermolecular forces, that are harder to break. It is the opposite for short chains.
49
Hydrocarbon oxidising
Hydrogen (H(2)) Carbon (C)
+Oxygen
Water (H(2)O) Carbon dioxide (CO(2)) - or carbon monoxide (CO), which is
poisonous, when there is a lack of oxygen
50
Steps to splitting crude oil into fractions
1. The crude oil is heated and vapourised. It is then passed into the bottom of a fractionating column and the gas will rise.
2. The temperature of the fractionating column is carefully controlled. It is cooler at the top and hotter at the bottom. → temperature gradient
3. The hydrocarbons will rise and begin to cool down and condense back to a liquid at its boiling point.
4. Each liquid fraction is then piped off, while the gases with lower boiling points continue to rise.
5. The fractions are separated with the higher boiling points collected near the bottom and the smaller fractions with lower boiling points are collected nearer the top.
51
Draw the rough shape of the fractionating column
N/a
52
Levels of the fractionating column
Top —> Bottom
**Refinery Gases** (remain a gas, do not condense): used in bottled gas (short chain), <20 °C
**Gasoline**: fuel for cars, 20-70 °C
**Kerosene**: aircraft fuel, 70-160 °C
**Diesel**: fuel for cars, lorries, buses, 160-250 °C
**Fuel Oil**: for ships, power stations, 250-350 °C
**Bitumen**: for roads and roofs (tar-like, long chain), 350 °C
53
Draw the bubble caps and taps in the fractionating column
N/a
54
Top of the fractionating column
- very volatile
- flows easily
- ignites easily
- low boiling point ranges
55
Bottom of the fractionating column
- not very volatile
- doesn’t flow easily
- doesn’t ignite easily
- high boiling point
56
Another word for the fractions condensing
Being ‘tapped’ out of the fractionating column
57
A fuel is…
A substance that produces large amounts of energy when burned during combustion. The energy contents of fuels vary, as they generate different amounts of energy when they burn.
58
When elements react with the oxygen in the air…
They form oxides
59
Draw the apparatus to test for carbon dioxide and water in combustion
N/a
60
How do the gases move through the apparatus?
Where there is a fast-flowing liquid, pressure drops, creation a suction effect for the gases.
61
What do you burn in a candle?
Wax. It soaks into the wick, and is burned, being a hydrocarbon.
62
What does the funnel do?
Catch or trap the products of combustion
63
Why is the funnel upside down?
In order to trap or catch the carbon dioxide and water
64
Why is the U-tube surrounded by ice?
The ice cools the gases, hence the water vapour condenses into water.
65
Testing for carbon dioxide (CO(2))
- limewater
- goes from a colourless to cloudy liquid
66
Testing for water (H(2)O)
First Substance: anhydrous copper sulphate (CuSO(4)) - goes from white solid to blue solid
Second Substance: anhydrous cobalt chloride (CoCl(2)) - goes from blue solid to pink solid
67
Anhydrous means…
Dehydrated
68
Anhydrous cobalt chloride and anhydrous copper sulphate…
Work in water, water vapour and impure water, as long as water is present
69
What are the steps to the combustion test?
1. Combustion
2. Test for water (in the U-tube)
3. Test for carbon dioxide
70
Two products of complete combustion
Water + Carbon Dioxide
71
Methane is a… (state of matter)
Gas
72
Octane is a… (state of matter)
Liquid
73
What forms on the funnel of the combustion test?
Soot, due to the lack of oxygen necessary to fully oxidise the carbon.
74
Bunsen Burner demonstration
1. Hold a piece of pot above a Bunsen Burner flame, using tongs
2. Keep the air hole closed
3. After a bit, record your observations of the bottom of the pot
4. Repeat steps 2-3 with an open airhole
75
With the air hole closed…
There is an orange flame (safety flame), and black soot is deposited on the bottom of the pot, as a result of incomplete combustion (inadequate oxygen was present, with the air hole closed)
76
With the air hole open…
A blue flame (roaring flame) appears, and nothing is deposited on the bottom of the pot, as there was complete combustion (enough oxygen was present, with the air hole open)
77
What dangerous product can be formed when a hydrocarbon fuel is burned in a limited supply of air?
Carbon monoxide
78
Why is carbon monoxide toxic?
Carbon monoxide is harmful because it binds to haemoglobin in the blood more strongly than oxygen does, so it prevents oxygen from being carried around the body in the blood.
79
Two products of incomplete combustion
Carbon monoxide, and sometimes small particles of carbon
80
Sulphur dioxide is harmful to…
Asthmatics. Sulphur dioxide is harmful to asthmatics because it irritates the airways and lungs, making it harder to breathe. This can trigger asthma attacks and cause coughing, wheezing, and shortness of breath.
81
Cause of acid rain
Two gases formed in the combustion of hydrocarbons: NO(2) and SO(2)
82
How does nitrogen dioxide form during combustion?
Nitrogen is found when car engines heat or gain pressure, hence the O(2), from the air, and the N(2) react together to form NO(2).
83
How does sulphur dioxide form during combustion?
Sulphur is found when there are impurities in fuel. Hence, the sulphur burns in the oxygen when the fuel burns to form SO(2).
84
How does acid form end up forming?
NO(2) and SO(2) in rain, forms acid rain
