Topic 7 - Organic Chemistry Flashcards
1
Q
What is a hydrocarbon
A
Any that is formed from carbon and hydrogen atoms only
2
Q
What is the formula for alkanes
A
CnH2n+2
3
Q
What is the homologous series
A
A group of organic compounds that react in a similar
4
Q
What are alkanes ( 3 points)
A
-The simplest type of hydrocarbon you can get
-Saturated compounds (each carbon atoms forms four single covalent)
-They are a homologous series
5
Q
What are the first four alkanes
A
Methane, ethane, propane and butane
6
Q
How does the length of the carbon affect how runny it is
A
The shorter the chain the more runny it is (less viscous)
7
Q
How does the length of a carbon chain affect how volatile it is
A
The shorter the chain the more volatile, so it will have a lower boiling point
8
Q
How does the length of a carbon chain affect how flammable it is
A
The shorter the chain the more flammable the hydrocarbon is
9
Q
What are short chain hydrocarbons used for in fuel and why
A
As they have lower boiling points they are used as ‘bottled gases’ - stored under pressure as liquids in bottles
10
Q
What does the complete combustion of any hydrocarbon in oxygen release
A
Lots of energy
11
Q
What waste products are formed from the complete combustion of any hydrocarbon in oxygen
A
Carbon dioxide and water vapour
12
Q
Write the equation of complete combustion of any hydrocarbon in oxygen
A
hydrocarbon + oxygen > carbon dioxide + water (+energy)
13
Q
During combustion what happens to both the hydrogen and carbon from the hydrocarbon
A
They are oxidised
14
Q
Why are hydrocarbons used as fuels
A
-Due to the amount of energy released when they combust completely
15
Q
What is crude oil
A
A fossil fuel
16
Q
How is crude oil formed
A
-From the remains of plants and animals, mainly plankton that died millions of years ago and were buried in mud
-Over millions of years high temperature and pressure turns the remains to crude oil which can drilled up from the rocks where it’s found
17
Q
What is the problem with crude oil being a fossil fuel
A
Like coal, oil and gas it is non-renewable fuels as they so long to make that they’re being used up much faster than they’re being formed so they’re finite resources
18
Q
Why does crude oil have to be separated by fractional distillation
A
As it is a mixture of lots of different hydrocarbons, most of which are alkanes the different compounds have to be sepersted
19
Q
How does fractional distillation work
A
- The oil heated until most of it has turned to gas which enters a fractioning column (and the liquid bit is drained off)
- In the column there’s a temperature gradients (hot at bottom cooler as it goes up)
- Longer carbons have high boiling points so condense into liquids and drain out of the column early on, near the bottom. The shorter hydrocarbons gave lower boiling points and condense and drain out much later near the top of the column
- You end up with the crude oil mixture separated out into different fractions, and each contains a mixture of hydrocarbons that all contain a similar number of carbon atoms, so have similar boiling points
20
Q
What is the order of fuels that condense in the fractioning column from earliest to latest
A
Bitumen
Heavy fuel oil
Diesel oil
Kerosene
Petrol
Liquefied Petroleum Gas
21
Q
Approximately how many carbon atoms are in LPG
A
3
22
Q
Approximately how many carbon atoms are in Petrol
A
8
23
Q
Approximately how many carbon atoms are in kerosene
A
15
24
Q
Approximately how many carbon atoms are in diesel oil
A
20
25
Approximately how many carbon atoms are in heavy fuel oil
40
26
What is feedstock
A feedstock is a raw material used to provide reactants for an industrial reaction
27
What feedstock are hydrocarbons from crude oil used for
They make new compounds in things such as:
-polymers
-solvents
-lubricants
28
What are organic compounds
Compounds containing carbon atoms
29
Why do you get a large variety of products made from crude oil
Carbon can bond to form different groups called homologous series which contain similar compounds with many properties in common
30
What can heavy fuel oil be (3)
-Heating oil
-Lubricating oil
-Fuel oil
31
Why do short-chain carbons make good fuels
They are flammable
32
What happens to less useful long chain hydrocarbons
They are turned into smaller, more useful hydrocarbons through a process called cracking
33
What are alkenes
-A type of hydrocarbon
-Used as a starting material when making lots of other compounds and can be used to make polymers
-They are unsaturated as they have a double carbon - carbon bond
34
What does cracking produce
-Shorter hydrocarbon chains
-Alkenes
35
What can products of cracking be used for
-Use as fuels (e.g. petrol for cars and paraffin for jet fuel)
36
What type of reaction is cracking
Thermal decomposition
37
What is a thermal decomposition reaction
Breaking down molecules by heating them
38
How does catalytic cracking work
1. Heat long chain hydrocarbons till they’re vaporised
2. Pass the vapour over a hot powdered catalyst (aluminium oxide)
3. The molecules will split apart on the surface of the catalyst
39
How does steam cracking work
-Vaporise the hydrocarbons, mix them with steam and heat them to a very high temperature
-This causes the long chains to split into smaller ones
40
What is a saturated compound
Being an organic compound having no double or triple bonds between carbon atoms
41
What does alkenes being unsaturated mean
-As they have a double bond between two carbon atoms in the chain they have two fewer hydrogens compared to alkanes containing the same number of carbon atoms
42
Why are alkenes more reactive than alkanes
-They are carbon double bonds so can open up to make a single bond allowing the two carbon atoms to bond with other atoms
43
What are the first four alkenes
-Ethene
-Propene
-Butene
-Pentene
44
What is the general formula for alkenes
CnH2n
45
What happens to alkenes in a large amount of oxygen
They completely combust only producing water and carbon dioxide
46
Why do alkenes tend to undergo incomplete combustion when burnt
There isn’t enough oxygen in the air
47
What happens in the incomplete combustion of alkenes
-Carbon dioxide and water produced, but also can produce carbon and carbon monoxide which is a poisonous gas
-Results in smoky yellow flame and less energy released compared to complete combustion
48
General equation for incomplete combustion
alkene + oxygen > carbon + carbon monoxide + carbon dioxide + water (+ energy)
49
Why do all alkenes react in similar ways and how do they mostly react
-They all have the functional group ‘C=C’
-Most of the time alkenes react via addition reactions. The carbon-carbon double bond will open to leave a single and a new atom is added to each carbon
50
Outline hydrogenation
-Hydrogen can react with the double-bonded carbons to open up the double bond and form the equivalent, saturated, alkane.
-There is a presence of a catalyst (nitrogen catalyst)
-And around 150°C
51
Outline hydration and give ethene example
-When alkenes react with steam, water is added across the double bond and an alcohol is formed (e.g. ethanol can be made by mixing ethene with steam and then passing it over a catalyst)
-The conversion of ethene to ethanol is a way of making ethanol industrially and after the reaction has taken place the reaction mixture is passed from the reactor into a condenser. Ethanol and water have a higher boiling point than ethene, so both condense whilst any unreacted ethene is recycled back into the reactor. The alcohol can be purged by fractional distillation.
52
Outline halogenation and give an example
-Alkenes will also react in addition reactions with halogens such as bromine, chlorine and iodine. The molecules are saturated, with the C=C carbons each becoming bonded to a halogen atom
-For example, bromine and ethene react together to form dibromoethane
53
How is bromine used to test for alkenes
-When orange bromine water is added to a saturated compound, like an alkane, no reaction will happen and it’ll stay bright orange
-If it’s added to an alkene the bromine will add across the double bond, making a colourless dibromo-compound so the bromine water is decolourised
54
What is polymerisation and what conditions does it need
-The reaction when small molecules named monomers join together and long molecules called polymers
-Usually needs pressure and a catalyst
55
What is plastic made of
Polymers that are usually carbon based and their monomers are often alkenes
56
Outline addition polymerisation
-The monomers that make up addition polymers have a double covalent bond
-Lots of unsaturated monomer molecules can open up their double bonds and join together to form polymer chain. This is called addition polymerisation (e.g. lots of ethene molecules can react together to form polythene
-When the monomers react in addition polymerisation reactions, the only product is the polymer, so an addition polymer contains exactly the same type and number of atoms as the monomers that formed it
57
How do you draw the repeating unit of a polymer
-Draw the two alkene carbons, replace the double bond with a single bond and add an extra single bond to each of the carbons
-Then fill in the rest of the groups in the same way that they surrounded the double bond i. the monomer. Finally, stick a pair of brackets around the repeating bit, and put an ‘n’ after it
58
What is the general formula alchohol
CnH2n+1OH
59
What is alcohols functional group
-OH functional group
60
Outline alcohol combustion
-Alcohols are flammable and they undergo complete combustion in air to produce carbon dioxide and water
-When less oxygen is present, incomplete combustion will occur, producing water and either carbon monoxide or carbon.
61
How do the first four alcohols react in water
-They are all soluble in water and their solutions have a neutral pH however the solubility decreases as the length of the alcohol molecule
62
Outline alcohols reacting with sodium
If a small piece of sodium is dropped into ethanol, bubbles of hydrogen gas are produced and the liquid contains sodium ethoxide.
63
Outline alcohol oxidisation
The alcohols can also be oxidised without combustion to produce carboxylic acids. For example, ethanol can be oxidised to ethanoic acid using an oxidising agent.
64
Why are alcohols used as solvents
-Alcohols such as methanol and ethanol are used as solvents in industry. This is because they can dissolve most things water can dissolve, but they can also dissolve substances that water can’t dissolve (e.g. hydrocarbons, oils and fats)
65
Outline alcohols used in fuels
-The first four alcohols are used as fuels. For example, ethanol is used as a fuel in spirit burners - it burns fairly cleanly and it’s non-smelly.
66
How is fermentation used to produce ethanol
-Fermentation uses an enzyme in yeast to convert sugars into ethanol. CO2 is also produced. The reaction occurs in solution so the ethanol produce is aqueous
-Happens fastest at a temperature of 37°C in a slightly acidic solution and under anaerobic conditions
-Under these conditions the enzyme in yeast works best to convert the sugar to alcohol. If the conditions were different the enzyme could be denatured or work at a slower rate.
67
What is the equation for fermentation producing ethanol
sugar > ethanol + carbon dioxide
yeast
68
What are carboxylic acids
A homologous series of compounds that all have ‘-COOH’ as a functional group. Their names end in ‘anoic’
69
How do carboxylic acids react with carbonates
-They produce a salt, water and carbon dioxide
-The slats formed in these reactions end in -anoate (e.g. methanol acid will form a methanoate’
70
How do carboxylic acids react with water
-They dissolve in water and when they dissolve they ionise and release H+ ions resulting in an acidic solution. They don’t ionise completely they just form weak acidic solutions. This means that they have a higher pH than aqueous solutions of strong acids with the same concentration.
71
What are esters
-Esters have the functional group ‘-COO-‘
-Esters are formed from an alcohol and a carboxylic acid
-An acid catalyst is usually used (e.g. concentrated sulphuric acid)
72
What is the equation for a reaction that produces an ester
alcohol + carboxylic > ester + water
acid catalyst
73
Outline condensation polymerisation
-Involves monomers which contain different functional groups.
-The monomers react together and bonds form between them, making polymer chains.
-For each new bond that forms, a small molecule is lost.
-The simplest types of condensation polymers contain two different types of monomer, each with two of the same functional groups
74
Differences between addition and condensation polymerisation in terms of number of types of monomers
-Addition polymerisation only has one monomer type containing a C=C bond
-condensation polymerisation has two monomer types containing two of the same functional group or one monomer type with two different functional groups
75
Differences between addition and condensation polymerisation in terms of number of products
-Addition polymerisation only forms one product
-Condensation polymerisation forms two types of product (the polymer and a small molecule)
76
Differences between addition and condensation polymerisation in terms of functional groups involved in polymerisation
-Addition polymerisation involves carbon-carbon double bond in monomer
-Condensation polymerisation involves two reactive groups on each monomer
77
What do amino acids contain
-Two different functional groups- a basic amino group (NH2) and an acidic carboxyl group (COOH)
78
How do amino acids form polymers
-Form polymers known as polypeptides through condensation polymerisation
-The amino group of an amino acid can react with the acid group of another to form a polymer chain and every new bond that is formed a molecule of water is lost
-One or more long chains of polypeptides are known as proteins. They have uses in the body such as enzymes work as catalysts, haemoglobin transports oxygen, antibodies form part of the immune system, and the majority of body tissue is made from proteins
-Polypeptides and proteins can contain different amino acids in their polymer chains. The order of the amino acids is what gives proteins their different properties and shapes.
79
What is DNA (overview)
Found in every living thing and many viruses. It contains genetic instructions that allow the organism to develop and operate. It’s a large molecule that takes a double helix structure.
80
What is DNA made up of
-Two polymer chains called nucleotides that each contain a small molecule known as a ‘base’
-The bases on the different polymer chains pair up with each other and form cross links keeping the two strands of nucleotides together and giving the double helix structure
-The order of the base acts as a code for genes
81
How do simple sugars form polymers
-They are small molecules that contain carbon, oxygen and hydrogen.
-They can react together through polymerisation reactions to form larger carbohydrate polymers (e.g. starch which living things use to store emery and cellulose which is found in plant cell walls)
