organic chem Flashcards
(97 cards)
1
Q
what is crude oil
A
remains of an ancient biomass consisting mainly of plankton that was buried in mud - high temp. and pressure converted these into crude oil
2
Q
what is crude oil a mixture of
A
very large number of compounds, most of the compounds in crude oil are hydrocarbons
3
Q
what is a hydrocarbon
A
molecules made up of hydrogen and carbon atoms only
4
Q
what homologous series are most of the hydrocarbons in crude oil a part of
A
alkanes - saturated hydrocarbons
5
Q
what does ‘saturated’ mean
A
each atom has formed bonds with as many other atoms as they can
- single bonds only
6
Q
what is the general formula for alkanes
A
C(n)H(2n+2)
7
Q
what are the first four alkanes
A
methane, ethane, propane and butane
8
Q
what are the properties of mixtures
A
- no chemical bonds between diff. parts of the mixture (diff. hydrocarbon molecules aren’t chemically bonded to one another)
- all keep original physical properties such as their boiling points
- properties of a mixture are a mixture of properties of the separate parts
9
Q
how can we separate crude oil
A
- can be separated out by physical methods
- can be split up into its separate fractions by fractional distillation
- each fraction contains molecules w/ a similar number of carbons to each other
10
Q
describe the fractional distillation of crude oil
A
1) crude oil is vaporised and fed into bottom of column where its hottest
2) column gets cooler as you go up, vapour rises up
3) fractions condense off when they reach their boiling point
4) larger molecules condense at bottom
5) smaller molecules condense at the top
11
Q
what can the fractions be processed for
A
produce fuels and feedstock for the petrochemical industry
12
Q
what fuels can be made from crude oil
A
many of the fuels on which we depend for our modern lifestyle, such as petrol, diesel oil, kerosene, heavy fuel oil and liquefied petroleum gases
13
Q
what materials are produced by petrochemical industry
A
solvents, lubricants, polymers, detergents
14
Q
why do so many natural and synthetic carbon compounds occur
A
bc of the ability of carbon atoms to form families of similar compounds
15
Q
what properties depend on the size of hydrocarbons
A
boiling point, viscosity, flammability - influence how hydrocarbons are used as fuels
16
Q
what do small molecules have
A
- less intermolecular forces
- lower bp
17
Q
what do large molecules have
A
- more intermolecular forces
- higher bp
18
Q
the shorter the molecule…
A
- the more runny the hydrocarbon is, or the less viscous it is
- the more volatile they are ( turn into gas @ lower temp)
- more flammable the hydrocarbon is
- the cleaner the flame (less sooty, smoky it is)
longer hydrocarbons have opposite properties
19
Q
why do we burn fossil fuels
A
burn coal, oil and natural gas to get energy for many processes
20
Q
what happens during combustion
A
carbon and hydrogen react w/ oxygen in air so that carbon dioxide and water vapour are released into the atmosphere
- carbon and hydrogen are said to be oxidised and energy is released
21
Q
what is combustion called when there is plenty of oxygen
A
complete combustion
22
Q
what happens when a fuel is completely combusted
A
carbon dioxide and water vapour are produced
23
Q
what is the equation for the complete combustion of a hydrocarbon
A
hydrocarbon + oxygen (g) -> carbon dioxide (g) + water vapour (g)
24
Q
what can hydrocarbons be broken down into
A
smaller, more useful molecules
25
what is cracking
a thermal decomposition reaction - breaking down molecules by heating them
26
what are the diff. types of cracking
catalytic and steam cracking
(for both, the long chain hydrocarbon must be vaporised)
27
what is catalytic cracking
vaporised long-chain alkane passed over hot, powdered catalysts (e.g. aluminium oxide). the long-chain molecules split, or crack, on the surface of the catalyst
28
what is steam cracking
vaporised long-chain alkane is mixed with steam and heated to a v. high temp.
29
what are most of the products of cracking
smaller alkanes and unsaturated hydrocarbons called alkenes
30
why is cracking important
- helps match supply of shorter alkanes w/ the demand for them
- produces alkenes, which are useful as feedstock (raw materials) for the petrochemical industry (e.g. making plastics)
31
what are alkenes
- hydrocarbons with a double carbon bond
- more reactive than alkanes
32
what is the test for alkenes
- reaction w/ bromine water
- an alkene will decolourise it, turning it from orange to colourless.
33
why are alkenes called unsaturated hydrocarbons
contain 2 fewer hydrogen atoms than alkane with the same number of carbon atoms
34
what is the general formula for alkenes
C(n)H(2n)
35
what are the first four alkenes
ethene, propene, butene, pentene
36
what is the. functional group of alkenes
C=C
37
what type of combustion do alkenes tend to undergo
incomplete combustion (unless there is enough O2)
- produces an orange smoky flame
38
what is the general equation for the incomplete combustion of alkenes
alkene + oxygen -> carbon dioxide + carbon monoxide + carbon + water vapour
- releases less energy than complete combustion
39
what are addition reactions of alkenes
where two molecules combine and form only one product. the double bond opens up and two atoms (or group of atoms) are added
40
what is hydrogenation
ADDITION OF HYDROGEN:
- when an alkane reacts w/ hydrogen gas , two hydrogen atoms are added across/ on either side of the double bond. the corresponding saturated alkane is the products
41
what is a halogenation reaction
ADDITION OF HALOGENS:
- when an alkene reacts with halogens (bromine, iodine, chlorine etc.) each carbon atom at the double bond gains a halogen atom
(does not matter where u draw them, but make sure there is only one halogen on each carbon atom)
42
what is a hydration reaction
ADDITION OF WATER:
- when alkenes react w/ steam, water is added across the double bond: H on one carbon atom and OH on the other. the product is an alcohol
- a catalyst is needed for this reaction.
43
what happens when propene or butene undergo a hydration reaction
propene + butene:
- diff. alcohol compounds can be made depending on which C the -OH group bonds w/.
44
what functional group do alcohols contain
-OH
45
what is the general formula for alcohols
C(n)H(2n+1)OH
46
what are the first four alcohols
methanol, ethanol, propanol, butanol
47
where is ethanol found
alcoholic beverages such as beer and wine
48
what has ethanol been used for recently
as a biofuel additive to regular automobile fuel such as petrol. (some run on ethanol alone)
49
how is ethanol produced
fermentation
- aqueous solutions of sugars are added to yeast, anaerobically
50
what is the equation for fermentation
glucose -> ethanol + carbon dioxide
51
what are the conditions for the fermentation of yeast
- warm temps. (25-35°C) necessary so reaction isn't too slow
- when temps. are hotter, enzymes denature (no longer function = no fermentation)
52
describe the process of fermentation
1) a crop is harvested
2) process the crop into smaller pieces
3) starch/cellulose broken down into glucose
4) sugars and yeast are added in container and CO2 is allowed to escape but air is prevented from entering
5) sugars are fermented
6) the ethanol is distilled to purify it
53
what is methanol used for
as a chemical feedstock
54
what is ethanol used for (generally)
- drinks
- as a solvent
55
what is propanol used for
- as a solvent
- fuel
56
what is butanol used for
- as a solvent
- fuel
57
what are methylated spirits
(denatured alcohol) mostly ethanol but contain toxic methanol and other ingredients.
- excellent solvent
- purposely dyed purple and foul smelling and tasting additives are added to deter people from consuming it
58
what happens when an alcohol reacts w/ the oxygen in the air
undergoes complete combustion (an oxidation reaction) to produce carbon dioxide and water
59
what happens when ethanol reacts with air
ethanol + oxygen -> carbon dioxide + water
60
what happens when there isn't sufficient enough oxygen when reacting with an alcohol
incomplete combustion will occur
61
what happens when an alcohol and sodium react
an alkoxide and hydrogen gas are formed
62
what is the general equation for the reaction of sodium and an alcohol
alcohol + sodium -> sodium alkoxide and hydrogen gas
63
what alcohols are completely miscible (soluble) in any proportion
the first three - methanol, ethanol, propanol
64
what is butanol's solubility in water
not soluble in any proportion - only slightly soluble
65
what happens when a large amount of butanol is added to water
only a specific (max.) amount will dissolve in a given vol. of water. the rest will remain undissolved as a separate layer.
66
what happens to an alcohol's solubility when it has a longer carbon chain length than 3
becomes increasingly less soluble
67
what is an oxidising agent
oxidises another substance/ causes another substance to lose electrons
68
what happens when an alcohol reacts with an oxidising agent
a carboxylic acid and water is formed
69
what is the general equation for the reaction of an alcohol with an oxidising agent
alcohol + oxidising agent -> carboxylic acid + water
70
what happens when ethanol reacts with an oxidising agent
ethanol + oxidising agent -> ethanoic acid + water
71
what functional group do carboxylic acids have
-COOH
72
what are the first 4 carboxylic acids
- methanoic acid
- ethanoic acid
- propanoic acid
- butanoic acid
73
what is the general formula for carboxylic acids
C(n)H(2n+1)COOH
74
why are carboxylic acids weak
they only partially dissociate in water
75
what happens when you dissolve carboxylic acids in water
CH3COOH -> CH3COO(-) + H(+)
76
what happens when you react a carboxylic acid with a carbonate
an ethanoate, water and carbon dioxide are formed
- an example of a neutralisation reaction
77
what happens when you react ethanoic acid with sodium carbonate
ethanoic acid + sodium carbonate -> sodium ethanoate + water + carbon dioxide (bubbles show reaction)
78
what happens when carboxylic acids undergo neutralisation reactions w/ a base
form a salt and water
79
what happens when carboxylic acids react with metals
produce salt and hydrogen
80
what happens when a carboxylic acid reacts with an alcohol
an ester and water are produced
81
what is the general equation for the reaction between a carboxylic acid and an alcohol
carboxylic acid + alcohol -> ester + water
82
give the reaction equation between ethanoic acid and ethanol
ethanoic acid + ethanol -> ethyl ethanoate + water
83
what is an ester and its functional group
group of organic compounds with the functional group -COO
84
what are esters used for
as they smell fruity they can be added to products to give them a fruity aroma or smell, often added to polymers
85
what is a polymer
when small covalent molecules bond together in a repeating pattern to form v. large molecules.
- the repeating units are called monomers
86
what is addition polymerisation
- monomers bond to form a polymer and the monomers add together to produce only one product
87
what hydrocarbon does addition polymerisation involve
alkenes
88
how does addition polymerisation work
the double bond of the alkene monomer "breaks open", allowing the alkene molecules to join together in a chain
89
what is condensation polymerisation
involves monomers with 2 functional groups. when these type of monomers react they join together, usually losing small molecules such as water.
- the simplest polymers are produced from two diff. monomers with 2 of the same functional group on each monomer
90
what is the diff. between addition and condensation polymerisation
- for addition the monomers must have an unsaturated bond - e.g. alkene
- in addition only 1 product is formed
- addition forms non-biodegradable polymers
- for condensation the monomers must each have 2 functional groups
- condensation forms 2 products. -polymer and by product
- condensation forms biodegradable polymers
91
what is an amino acid
an organic molecule which contains a central carbon atom which is bonded to:
- an amino group -NH2
- a carboxyl group -COOH
- a hydrogen atom
- an 'R' group which is usually a carbon chain
92
how many functional groups do amino acids have
2
93
what type of polymerisation reactions do amino acids take part in
condensation polymerisation
- polymer formed = polypeptide
94
how can amino acids bond to form proteins
in a specific sequence to produce specific polypeptides and proteins w/ a specific 3D structure.
95
what is DNA
- DNA (deoxyribonucleic acid) is a large polymer found in the nucleus of cells.
- essential for life as it contains info for the sequence of amino acids in proteins and genes.
96
what are the monomers of DNA called
nucleotides
97
what are the 4 bases that can be found in a nucleotide
- adenine
- cytosine
- guanine
- thymine
