11. Organic chemistry Flashcards
What is organic chemistry?
Organic Chemistry is the scientific study of the structure, properties, and reactions of organic compounds
What are organic compounds?
Organic compounds are those which contain carbon
What 3 compounds are not considered to be organic compounds?
For conventional reasons metal carbonates, carbon dioxide and carbon monoxide are not included in organic compounds
What is a hydrocarbon?
A compound that contains only hydrogen and carbon atoms
What is the general formula?
A formula that states the ratio of atoms of each element in the formula of every compound in a particular homologous series
What is the structural formula?
Condensed representation that shows the symbols for each atom in a compound with straight lines joining them to represent the covalent bonds
What is the displayed formula?
graphic representation that shows the symbols for each atom in a compound with straight lines joining them to represent the covalent bonds
What types of combustion do hydrocarbons undergo?
These compounds undergo complete and incomplete combustion
When does complete combustion occur?
Complete combustion occurs when there is excess oxygen
Chemical Equation for complete combustion of methane?
CH4+ 2O2→CO2+ 2H2O
When does incomplete combustion occur?
Incomplete combustion occurs when there is insufficient oxygen to burn
What is formed when complete combustion occurs?
water and carbon dioxide form
What is formed when incomplete combustion occurs?
either carbon monoxide and water or carbon and water form
What are the two possible chemical equations for methane during incomplete combustion?
2CH4+ 3O2→ 2CO + 4H2O
CH4+ O2→ C + 2H2O
What does the prefix “meth” tell you about a compound?
contains 1 carbon atom
What does the prefix “eth” tell you about a compound?
contains 2 carbon atoms
What does the prefix “prop” tell you about a compound?
contains 3 carbon atoms
What does the prefix “but” tell you about a compound?
contains 4 carbon atoms
What does the suffix “ane” tell you about the family of a compound?
alkane
What does the suffix “ene” tell you about the family of a compound?
alkene
What does the suffix “anol” tell you about the family of a compound?
alcohol
What does the suffix “anoic acid” tell you about the family of a compound?
carboxylic acid
What does the suffix “amine” tell you about the family of a compound?
amine
What does the suffix “yl … annotate” tell you about the family of a compound?
ester
What is it important to remember when there is more than one carbon atom on which the functional group can be located?
When there is more than one carbon atom where a functional group can be located it is important to distinguish exactly which carbon the functional group is on
When would the prefix di be used?
When 2 functional groups are present di- is used as a prefix to the second part of the name
Why does branching need to be considered when naming compounds?
Branching also needs to be considered, the carbon atoms with the branches are described by their number
Does the functional group or the branch take precedence?
When the location of functional groups and branches needs to be described the functional group takes precedence so the functional group has the lowest number
What is the chemical formula of methane?
CH4
What is the chemical formula of ethane?
C2H6
What is the chemical formula of propane?
C3H8
What is the chemical formula of butane?
C4H10
What are the 4 compounds in the alkane group?
methane
ethane
propane
butane
What is the chemical formula of ethene?
C2H4
What is the chemical formula of propene?
C3H6
What is the chemical formula of butene?
C4H8
What are the 3 compounds in the alkene group?
ethene
propene
butene
What is the chemical formula of methanol?
CH3OH
What is the chemical formula of ethanol?
C2H5OH
What is the chemical formula of propanol?
C3H7OH
What is the chemical formula of butanol?
C4H9OH
What are the 4 compounds in the alcohol group?
methanol
ethanol
propanol
butanol
What is the chemical formula of methanoic acid?
HCOOH
What is the chemical formula of ethanoic acid?
CH3COOH
What is the chemical formula of ethanoic acid?
CH3COOH
What is the chemical formula of propanoic acid?
C2H5COOH
What is the chemical formula of butanoic acid?
C3H7COOH
What are the 4 compounds in the carboxylic acids group?
methanoic acid
ethanoic acid
propanoic acid
butanoic acid
What is the name of the ester from ethanol and propanoic acid?
ethyl propanoic
What is the name of the ester from butanol and methanoic acid?
butyl methanoate
What is the name of the ester from pentanol and ethanoic acid?
pentyl ethanoate
What is a homologous series?
This is a series or family of organic compounds that have similar features and chemical properties
Why do all compounds in a homologous series have similar properties?
due to them having the same functional group
What 5 features do all members in a homologous series have?
The same general formula
Same functional group
Similar chemical properties
Gradation in their physical properties
The difference in the molecular formula between one member and the next is CH2
What is a functional group ?
This is a group of atoms which are bonded in a specific arrangement
what is the functional group responsible for?
responsible for the characteristic reactions of each member of a homologous series
What are the 6 functional groups?
alkane
alkene
alcohol
carboxylic acid
amine
ester
Draw structural formulas for all the functional groups
si
What is the functional group for alkane?
H H
| |
–C–C–
| |
H H
What is the functional group for alkene?
H H
| |
–C==C–
|
What is the functional group for alcohol?
–C–OH
What is the functional group for carboxylic acid?
O
||
–C–OH
|
What is the functional group for amine?
NH2
|
–C–
|
What is the functional group for ester?
O
|| |
–C–O–C–
|
What are structural isomers?
Compounds that have the same molecular formula but different structural formulae
Why do structural isomers exist?
This is due to the different arrangement of their atoms in space
What two things can be changed to create a structural isomer?
There are two types: chain and position
What is chain isomerism?
In chain isomerism the structure of the carbon chain differs
What is position isomerism?
In position isomerism, the position of the functional group differs
What is a fuel?
A fuel is a substance which when burned, releases heat energy
How can heat released from a fuel be useful?
This heat can be transferred into electricity, which we use in our daily lives
What are the most common fossil fuels?
Most common fossil fuels include coal, natural gas and hydrocarbons such as methane and propane which are obtained from crude oil
What is the main constituent of natural gas?
methane
What is another name for petroleum?
Petroleum is also called crude oil
What is petroleum made of?
a complex mixture of hydrocarbons which also contains natural gas
Where is petroleum found?
It is a thick, sticky, black liquid that is found under porous rock (under the ground and under the sea)
Is petroleum itself useful?
NO
Petroleum itself as a mixture isn’t very useful but each component part of the mixture, called a fraction, is useful and each fraction has different applications
How are the various fractions separated from each other?
The fractions in petroleum are separated from each other in a process called fractional distillation
Are the fractions in petroleum similar?
The molecules in each fraction have similar properties and boiling points, which depend on the number of carbon atoms in the chain
How do the boiling points and viscosity of the fractions change?
The boiling point and viscosity of each fraction increases as the carbon chain gets longer
- Where does fraction distillation occur?
fractional distillation
Fractional distillation is carried out in a fractionating column
- How does the temperature vary in a fractionating column?
fractional distillation
The fractionating column is hot at the bottom and cool at the top
- Where does crude oil enter and what happens?
fractional distillation
Crude oil enters the fractionating column and is heated so vapours rise
- What happens to vapours of hydrocarbons with high boiling points?
(fractional distillation)
Vapours of hydrocarbons with very high boiling points will immediately turn into liquid and are tapped off at the bottom of the column
- What happens to vapours of hydrocarbons with low boiling points?
(fractional distillation)
Vapours of hydrocarbons with low boiling points will rise up the column and condense at the top to be tapped off
- How are all the fractions successfully separated?
fractional distillation
The different fractions condense at different heights according to their boiling points and are tapped off as liquids.
- What size of hydrocarbons are collected at the top?
fractional distillation
The fractions containing smaller hydrocarbons are collected at the top of the fractionating column as gases
- What size of hydrocarbons are collected at the bottom?
fractional distillation
The fractions containing bigger hydrocarbons are collected at the lower sections of the fractionating column
What does viscosity mean?
refers to the ease of flow of a liquid
What does it mean if a liquid has a high viscosity?
High viscosity liquids are thick and flow less easily.
How does viscosity change as the carbon chain increases and why?
If the number of carbon atoms increases, the attraction between the hydrocarbon molecules also increases which results in the liquid becoming more viscous with the increasing length of the hydrocarbon chain.
The liquid flows less easily with increasing molecular mass
How does colour change as the length of the carbon chain increases?
Colour: As carbon chain length increases the colour of the liquid gets darker as it gets thicker and more viscous
How does the melting/boiling point change as the length of the carbon chain increases?
Why?
As the molecules get larger, the intermolecular attraction becomes greater. So more heat is needed to separate the molecules. With increasing molecular size there is an increase in boiling point
What does volatility refer to?
Volatility refers to the tendency of a substance to vaporise.
How does volatility change with an increasing carbon chain?
With increasing molecular size hydrocarbon liquids become less volatile.
Why does the liquid become less volatile as the carbon chain increases?
This is because the attraction between the molecules increases with increasing molecular size
What 8 fractions are produced by the fractional distillation of petroleum?
refinery gas
gasoline / petrol
naphtha
kerosene / paraffin
diesel / gas oil
fuel oil
lubricating oil
bitumen
What is a use for refinery gas?
heating and cooking
What is a use for gasoline?
fuel for cars (petrol)
What is a use for naphtha?
raw product for producing chemicals
What is a use for kerosene?
for making jet fuel (paraffin)
What is a use for diesel?
fuel for diesel engines (gas oil)
What is a use for fuel oil?
fuel for ships and for home heating
What is a use for lubricating oil?
for lubricants, polishes, waxes
What is a use for bitumen?
for surfacing roads
check boiling and melting points of fractions
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What type of carbon bonds do compounds in the alkane group have?
only single carbon bonds
What is the alkane group?
A homologous series of hydrocarbon compounds with only single carbon bonds, there are no C=C bonds present
What is the general formula of alkanes?
CnH2n+2
What type of hydrocarbons are alkanes?
Alkanes are classified as saturated hydrocarbons
What type of hydrocarbons are alkanes?
Alkanes are classified as saturated hydrocarbons
What does it mean if an alkane is saturated?
all the carbon bonds in alkanes are single bonds
What colour are alkanes?
They are colourless compounds
What changes across the alkane group?
have a gradual change in their physical properties as the number of carbon atoms in the chain increases
Are alkanes reactive?
Alkanes are generally unreactive compounds
What reactions can alkanes undergo? (3)
they undergo combustion reactions
can be cracked into smaller molecules
react with halogens in the presence of light
What fossil fuel is an alkane?
Methane is an alkane and is the major component of natural gas
What are the first 3 alkanes?
methane
ethane
propane
What is a substitution reaction?
In a substitution reaction, one atom is swapped with another atom
With what group do alkanes react with in a substitution reaction?
Alkanes undergo a substitution reaction with halogens
What condition must be present for a substitution reaction between halogens and alkanes to occur?
the presence of ultraviolet radiation
Word equation for methane and bromine
Methane + Bromine → Bromomethane + Hydrogen Bromide
Chemical Equation for methane and bromine
CH4 + Br2 → CH3Br + HBr
What is the alkene group?
A homologous series of hydrocarbon compounds with carbon-carbon double bonds (C = C)
What is the general formula for the alkene group?
CnH2n
What chemical characteristic do ALL alkenes have?
All alkenes contain a double carbon bond, which is shown as two lines between two of the carbon atoms
What is the double carbon bond present in alkenes known as?
This is the alkene functional group and is what allows alkenes to react in ways that alkanes cannot
What type of hydrocarbons are alkenes?
Compounds that have a C=C double bond are also called unsaturated compounds
Why is catalytic cracking used?
Although there is use for each fraction obtained from the fractional distillation of crude oil, the amount of longer chain hydrocarbons produced is far greater than needed
What is converted into what during catalytic cracking?
A process called catalytic cracking is used to convert longer-chain molecules into short-chain and more useful hydrocarbons
What is a product of cracking alkenes?
Alkenes and hydrogen are produced from the cracking of alkanes
What 2 alkenes are most commonly used in cracking and what do they produce?
Kerosene and diesel oil are often cracked to produce petrol, other alkenes and hydrogen
What 2 alkenes are most commonly used in cracking and what do they produce?
Kerosene and diesel oil are often cracked to produce petrol, other alkenes and hydrogen
- What is the first step for catalytic cracking?
catalytic cracking
Fractions containing large hydrocarbon molecules are heated at 600 – 700°C to vaporise them
- What happens to the hydrocarbon vapours?
catalytic cracking
Vapours will then pass over a hot catalyst of silica or alumina
- Why are the vapours passed over a hot catalyst? What reaction occurs?
catalytic cracking
This process breaks covalent bonds in the molecules, causing thermal decomposition reactions
- What happens as a result of these reactions?
catalytic cracking
As a result, cracking produces smaller alkanes and alkenes.
The molecules are broken up in a random way which produce a mixture of alkanes and alkenes
- What are the optimum conditions for catalytic cracking?
catalytic cracking
Hydrogen and a higher proportion of alkenes are formed at temperatures of above 700ºC and higher pressure
Do alkanes and alkenes have the same molecular structures?
NO
they have different ones
What is the difference between alkanes and alkenes referring to their carbon bonds?
All alkanes are saturated and alkenes are unsaturated
What chemical property allows us to differentiate between alkanes and alkenes?
The presence of the C=C double bond allows alkenes to react in ways that alkanes cannot
- What substance can be used to differentiate between alkanes and alkenes?
differentiating between alkenes and alkanes
bromine water
- What is bromine water?
differentiating between alkenes and alkanes
Bromine water is an orange coloured solution of bromine
- What will happen when bromine water is shaken with an alkane? Why?
differentiating between alkenes and alkanes
When bromine water is shaken with an Alkane, it will remain as an orange solution as alkanes do not have double carbon bonds (C=C) so the bromine remains in solution
- What will happen when bromine water is shaken with an alkene? Why?
differentiating between alkenes and alkanes
when bromine water is shaken with an alkene, the alkene will decolourise the bromine water and turn colourless as alkenes do have double carbon bonds (C=C)
- Why do the double carbon bonds decolourise the bromine water?
differentiating between alkenes and alkanes
The bromine atoms add across the C=C double bond hence the solution no longer contains the orange coloured bromine
- What is this decolorisation reaction called?
differentiating between alkenes and alkanes
This reaction between alkenes and bromine is called an addition reaction
- What is an addition reaction?
differentiating between alkenes and alkanes
A reaction in which a simple molecule adds across the carbon-carbon double bond of an alkene
- How are addition polymers formed? What makes them up?
addition polymerisation
Addition polymers are formed by the joining up of many small molecules called monomers
- In what monomers does addition polymerisation take place?
addition polymerisation
Addition polymerisation only occurs in monomers that contain C=C bonds
- What happens to the double carbon bonds during addition polymerisation? What new bonds are formed?
addition polymerisation
One of the bonds in each double bond breaks and forms a bond with the adjacent monomer
- What is an example of a polymer synthesised from alkene monomers? What is it made of?
addition polymerisation
A common example is poly-ethene (polythene) which is the addition of many ethene monomers
What is an example of an addition reaction?
ethene + bromine
What is formed between the addition reaction of ethene and bromine?
ethene + bromine –> 1,2-dibromoethane
- With what element do alkenes react to form alkanes?
hydrogenation reactions
Alkenes also undergo addition reactions with hydrogen in which an alkane is formed
- What is the reaction between alkenes and
hydrogen called?
h r
These are hydrogenation reactions
- What conditions are needed for hydrogenation reactions to occur?
hydrogenation reactions
occur at 150ºC using a nickel catalyst
- What practical use do hydrogenation reactions have?
hydrogenation reactions
Hydrogenation reactions are used to change vegetable oils into margarine to be sold in supermarkets
- What do alkenes react with to form alcohol?
hydration reactions
Alkenes also undergo addition reactions with steam in which an alcohol is formed
- What is the reaction called that turns alkenes into alcohol?
hr
Since water is being added to the molecule it is also called a hydration reaction
- What conditions are needed for hydration reactions to occur?
hydration reactions
Temperature of around 330ºC
Pressure of 60 – 70 atm
Concentrated phosphoric acid catalyst
- Where are hydration reactions important?
hydration reactions
The reaction is very important industrially for the production of alcohols
What are the alcohols?
Family of organic compounds that all contain the -OH functional group
What is the functional group?
This is the group of atoms responsible for their chemical properties and reactions
Which alcohol is considered the most important?
Ethanol (C2H5OH) is one of the most important alcohols
Where is ethanol found?
It is the type of alcohol found in alcoholic drinks such as wine and beer
It is also used as fuel for cars and as a solvent
What does alcohol produce when it burns?
Alcohols burn in excess oxygen and produce CO2 and H2O
Chemical equation for combustion of ethanol
C2H5OH(l) + 3 O2(g) ==> 2 CO2(g) + 3 H2O(g)
What two methods can be used to create ethanol?
The hydration of ethene with steam
The fermentation of glucose
- What is passed over what to create gaseous ethanol in the hydration of ethene?
hydration of ethene
A mixture of ethene and steam is passed over a hot catalyst of phosphoric acid
- What is the temperature and pressure?
hydration of ethene
temperature of 330°C
The pressure is used 60-70 atmosphere
- What happens to the gaseous ethanol?
hydration of ethene
The gaseous ethanol is then condensed into a liquid for use
- What is dissolved and what must be added to begin the process?
Fermentation of glucose
Sugar or starch is dissolved in water and yeast is added
- In what conditions is this mixture fermented?
Fermentation of glucose
The mixture is then fermented between 15 and 35°C with the absence of oxygen for a few days
- What does yeast contain which is useful for this reaction?
Fermentation of glucose
Yeast contains enzymes that break down starch or sugar to glucose
- What will happen if the temperature becomes too low?
Fermentation of glucose
If the temperature is too low the reaction rate will be too slow
- What will happen if the temperature becomes too low?
Fermentation of glucose
If the temperature is too low the reaction rate will be too slow
- What will happen if the temperature is too high?
Fermentation of glucose
if it is too high the enzymes will become denatured
- What do the yeast do to form ethanol? What other product is formed?
Fermentation of glucose
the yeast respire anaerobically using the glucose to form ethanol and carbon dioxide
- What is the chemical reaction for the fermentation of glucose?
Fermentation of glucose
C6H12O6 + Enzymes → 2CO2 + 2C2H5OH
- Why is ethanol production by fermentation a batch process?
Fermentation of glucose
The yeast are killed off once the concentration of alcohol reaches around 15%, hence the reaction vessel is emptied and the process is started again
What is the difference between the hydration of ethene and fermentation in terms of equipment?
H - complex set-up required
F - simple equipment needed
What is the difference between the hydration of ethene and fermentation in terms of the raw materials?
H - uses non-renewable resources (crude oil)
F - uses renewable resources (Sugar cane)
What is the difference between the hydration of ethene and fermentation in terms of the type of process?
H - continuous process
F - Batch Process - everything is
What is the difference between the hydration of ethene and fermentation in terms of the rate of reaction?
H - fast
F - slow
What is the difference between the hydration of ethene and fermentation in terms of the quality of product?
H - produces pure ethanol
F - produces a dilute solution requiring further processing
What is the difference between the hydration of ethene and fermentation in terms of the atmospheric effects?
H - no greenhouse gas is produced but pollutants are formed from the burning of fossil fuels to maintain a high temperature
F - CO2 produced which is a greenhouse gas
What is the difference between the hydration of ethene and fermentation in terms of the reaction conditions?
H - high temperatures and pressures required, increasing the energy input and cost
F- Low temperatures required
What does it mean when the hydration of ethene is referred to as a continuous process? Is this good or bad?
a stream of reactant is constantly passed over the catalyst. This is more EFFICIENT than a batch process
What does it mean when fermentation is referred to as a batch process? Is this good or bad?
everything is mixed together in a reaction vessel and then left for several days. That batch is then removed and a new reaction is set up - this is inefficient
What are carboxylic acids?
These are a homologous series of organic compounds that all contain the same functional group: –COOH
What colour are carboxylic acids?
They are colourless liquids
How strong are carboxylic acids?
are weakly acidic
What chemical properties do carboxylic acids have?
have typical acidic properties
What solutions do carboxylic acids react with?
They react with alkaline solutions
What colour do carboxylic acids turn blue litmus paper?
turn blue litmus red
What salts do carboxylic acids form?
form salts called ethanoates
What are the first 3 carboxylic acids?
methanoic acid
ethanoic acid
propanoic acid
What can ethanoic acid do in water?
Ethanoic acid is a typically weak acid and dissociates slightly in water
What is produced when ethanoic acid dissociates in water?
a mildly acidic solution
What is the ionic equation for the dissociation of ethanoic acid?
CH3COOH ⇌ H+ + CH3COO-
Where does the equilibrium lie during the ionisation of ethanoic acid?
far to the left
With what 3 compounds does ethanoic acid react with?
Ethanoic acid reacts with the more reactive metals, hydroxides and carbonates
What is produced when ethanoic acid reacts with metals?
In the reaction with metals a metal salt and hydrogen gas are produced
Give the chemical equation for the reaction between magnesium and ethanoic acid?
What is the salt formed in this reaction called?
2CH3COOH + Mg → (CH3COO)2Mg + H2
magnesum ethanoate
What is formed when ethanoic acid reacts with hydroxides? What type of reaction is this?
In the reaction with hydroxides a salt and water are formed in a neutralisation reaction
Give the equation for the reaction between potassium hydroxide and ethanoic acid
What is the name of the salt formed?
CH3COOH + KOH → CH3COOK + H2O
potassium ethanoate
What is formed when ethanoic acid reacts with carbonates?
In the reaction with carbonates a metal salt, water and carbon dioxide gas are produced
Give the equation for the reaction between potassium carbonate and ethanoic acid
What is the name of the salt formed?
2CH3COOH + K2CO3 → 2CH3COOK + H2O + CO2
potassium ethanoate
In what two ways can carboxylic acids be made?
Oxidation by fermentation
Oxidation with potassium manganate (VII)
- What is oxidised?
Oxidation by fermentation
The microbial oxidation of ethanol
- What will the microbial oxidation fo alcohol produce?
Oxidation by fermentation
a weak solution of vinegar (ethanoic acid).
- What happens when you leave a bottle of wine opened?
Oxidation by fermentation
bacteria in the air (acetobacter) will use atmospheric oxygen from air to oxidise the ethanol in the wine
The acidic, vinegary taste of wine which has been left open for several days is due to the presence of ethanoic acid
- What is the chemical equation for oxidation by fermentation to produce ethanoic acid?
Oxidation by fermentation
C2H5OH + O2 → CH3COOH + H2O
- What needs to be added to alcohols to create carboxylic acids?
o pm
Alcohols can also be oxidised to carboxylic acids by heating with acidified potassium manganate (VII)
- How I the heating of the solution performed?
Oxidation with potassium manganate (VII)
The heating is performed under reflux which involves heating the reaction mixture in a vessel with a condenser attached to the top
- Why is a condenser used?
Oxidation with potassium manganate (VII)
The condenser prevents the volatile alcohol from escaping the reaction vessel as alcohols have low boiling points
- What two compounds are used to make esters?
Making esters
Alcohols and carboxylic acids react to make esters
- What are the reactions that create esters called?
Making esters
esterification reactions
- What functional group do esters have?
Making esters
Esters are compounds with the functional group R-COO-R
- What do esters look like and where are they used?
Making esters
Esters are sweet-smelling oily liquids used in food flavourings and perfumes
- What is the catalyst used to create esters?
Making esters
concentrated sulfuric acid
- What will be formed when ethanoic acid reacts with ethanol?
Making esters
Ethanoic acid will react with ethanol in the presence of concentrated sulfuric acid (catalyst) to form ETHYL ETHANOATE
- Chemical equation for reaction between ethanoic acid and ethanol?
Making esters
CH3COOH + C2H5OH → CH3COOC2H5 + H2O
- Draw the compounds which are present in the reaction between ethanoic acid and ethanol and the products
Making esters
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- What does the first part of the name indicate?
Naming esters
The first part of the name indicates the length of the carbon chain in the alcohol,
- What does the first part of the name end in?
Naming esters
ends with the letters ‘- yl’
- What does the second part of the name indicate?
Naming esters
The second part of the name indicates the length of the carbon chain in the carboxylic acid
- What does the second part of the name end in?
Naming esters
ends with the letters ‘- oate’
- What is the name of the ester formed from pentanol and butanoic acid?
Naming esters
pentyl butanoate
What are polymers?
Polymers are large molecules built by linking 50 or more smaller molecules called monomers
What are the repeating units connected to each other by?
Each repeat unit is connected to the adjacent units via covalent bonds
What are homopolymers?
homopolymers contain just one type of unit
What are 2 examples of homopolymers?
polythene and polychloroethene, commonly known as PVC
What are copolymers?
Others contain two or more different types of monomer units and which are called copolymers
What are 2 examples of copolymers?
Examples include nylon and biological proteins
Do all polymers have the same linkages?
NO
Different linkages also exist, depending on the monomers and the type of polymerisation
What are 3 examples of linkages?
Examples of linkages are covalent bonds, amide links and ester links
What are examples of synthetic polymers?
Plastics, nylon and terylene
What type of polymer is nylon?
Nylon is a copolymer
How is nylon used?
used to produce clothing, fabrics, nets and ropes
What type of polymer is terylene?
Terylene is a polyester
What is terylene made from and what joins it together?
made from monomers which are joined together by ester links
How is terylene used?
Terylene is used extensively in the textile industry and is often mixed with cotton to produce clothing
What are 3 examples of plastics?
poly(e)thene
polypropene
polychloroethene
What is the repeating unit for polythene?
|~ H H ~|
| | | |
– |—C–C—| –
| | | |
|_ H H _| n
What is the repeating unit for polypropene?
|~ CH3 H ~|
| | | |
– |—C—–C—| –
| | | |
|_ H H _| n
What is the repeating unit for polychloroethene? PVC
|~ H Cl ~|
| | | |
– |—C–C—| –
| | | |
|_ H H _| n
What are uses of polythene? [2]
- plastic bags (low density polythene)
- plastic bottles (high density polythene)
What are uses of polypropene? [3]
food packaging
ropes
carpets
What are uses of polychloroethene? [4]
plastic sheets
artificial leather
drainpipes and gutters
insulation on wires
What are non-biodegradable plastics?
These are plastics which do not degrade over time or take a very long time to degrade, and cause significant pollution problems
Where is plastic pollution the biggest problem?
In particular plastic waste has been spilling over into the seas and oceans
Why is it a problem when plastic gets into oceans?
it causes huge disruptions to marine life
What problems do non-biodegradable plastics cause in landfills?
In landfills waste polymers take up valuable space as they are non-biodegradable so microorganisms cannot break them down.
This causes the landfill sites to quickly fill up
What problems do non-biodegradable plastics cause when they are incinerated? (complete combustion)
Polymers release a lot of heat energy when incinerated and produce carbon dioxide which is a greenhouse gas that contributes to climate change
What problems do non-biodegradable plastics cause when they are incinerated? (incomplete combustion)
If incinerated by incomplete combustion, carbon monoxide will be produced which is a toxic gas that reduces the capacity of the blood to carry oxygen
Why can polymers not be simply recycled?
Polymers can be recycled but different polymers must be separated from each other which is a difficult and expensive process
How are addition polymers formed?
Addition polymers are formed by the joining up of many monomers
In what monomers can addition polymerisation occur?
only occurs in monomers that contain C=C bonds
- what bonds are broken during addition polymerisation?
addition polymerisation
One of the bonds in each C=C bond breaks
- After the C=C bonds are broken, what new ones are formed?
addition polymerisation
forms a bond with the adjacent monomer
- What bonds does the polymer have?
addition polymerisation
the polymer being formed containing single bonds only
- What are polymers usually made of?
addition polymerisation
Many polymers can be made by the addition of alkene monomers
- if the polymer is not made of alkene monomers, what can it be made of?
addition polymerisation
Others are made from alkene monomers with different atoms attached to the monomer such as chlorine or a hydroxyl group
- if the polymer is not made of alkene monomers, what can it be made of?
addition polymerisation
Others are made from alkene monomers with different atoms attached to the monomer such as chlorine or a hydroxyl group
- How is the name of a polymer deduced?
addition polymerisation
The name of the polymer is deduced by putting the name of the monomer in brackets and adding poly- as the prefix
- What is the name of a polymer if propene is used?
addition polymerisation
polypropene
What happens during condensation polymerisation? What is removed?
Condensation polymers are formed when monomer molecules are linked together with the removal of a small molecule, usually water
What is used in condensation polymerisation?
Condensation polymerisation usually involves two different monomers, each one having a functional group on each end
How can condensation polymerisation be reversed?
Hydrolysing (adding water) to the compound in acidic conditions usually reverses the reaction and produces the monomers by rupturing the peptide link
What is used to display the formula of a polymer molecule?
Repeat units are used when displaying the formula
- What is different between the bonds in a monomer and a repeating unit?
(drawing repeating units)
Change the double bond in the monomer to a single bond in the repeat unit
- What needs to be added to each end when drawing a repeating unit?
(drawing repeating units)
Add a bond to each end of the repeat unit
- What must be remembered when drawing bonds on either side of a repeating unit?
(drawing repeating units)
The bonds on either side of the polymer must extend outside the brackets (these are called extension or continuation bonds)
- What symbol must be added outside the repeating unit? What does this show?
(drawing repeating units)
A small subscript n is written on the bottom right-hand side to indicate a large number of repeat units
How could you deduce the polymer from a monomer?
Identify the repeating unit in the polymer
Change the single bond in the repeat unit to a double bond in the monomer
Remove the bond from each end of the repeat unit and the subscript n
What type of polymer is nylon?
A POLYAMIDE - a polymer where the monomer units are joined together by amide (peptide) links
What is nylon made of?
made from dicarboxylic acid monomers and diamines
What is a dicarboxylic acid?
a carboxylic with a -COOH group at either end
What is a diamine?
an amine with an -NH2 group at either end
What groups react together in the formation of nylon?
Each -COOH group reacts with another -NH2 group on another monomer
What is formed during the formation of nylon?
An amide linkage is formed with the subsequent loss of one water molecule per link
What do carbohydrates provide?
Carbohydrates provide energy which is released during cellular respiration
Why are proteins important?
Proteins are the building blocks of cells and are essential for growth and all of the enzyme catalysts in the body are proteins
What type of polymers are proteins?
Proteins are condensation polymers
What monomers are proteins made from? What bonds join them?
formed from amino acid monomers joined together by peptide bonds, similar to the structure in Nylon
How does the structure of a protein differ from nylon?
The units in proteins are different however, consisting of amino acids
What are amino acids?
Amino acids are small molecules containing NH2 and COOH functional groups
how many amino acids do most proteins contain?
Most proteins contain at least 20 different amino acids
- What can proteins be hydrolysed by?
Hydrolysis of proteins
Proteins can be hydrolysed by the addition of water in acidic or alkaline conditions
- What conditions are used to hydrolyse proteins?
Hydrolysis of proteins
Heat and concentrated acid (usually 6 mol/dm3 HCl) are used with a reflux condenser
3.. Why is a reflux condenser used?
Hydrolysis of proteins
to prevent the acidic vapours from escaping the reaction vessel
- What is added after the reaction is complete?
Hydrolysis of proteins
Aqueous ammonia is added after completion to neutralise the excess acid
- What other substance can be used to hydrolyse proteins at room temperature?
Hydrolysis of proteins
Enzymes can also be used to hydrolyse some proteins at room temperature, mimicking natural bodily processes
What are carbohydrates made of?
Carbohydrates are compounds of carbon, hydrogen and oxygen
What general formula do carbohydrates have?
Cx(H2O)y
What two types of carbohydrates are there?
There are simple carbohydrates and complex carbohydrates
What are simple carbohydrates? Give examples
Simple carbohydrates are called monosaccharides and are sugars such as fructose and glucose
What are complex carbohydrates? Give examples
Complex carbohydrates are called polysaccharides such as starch and cellulose.
What type of polymers are complex carbohydrates?
These are condensation polymers formed from simple sugar monomers
What types of monomers are complex carbohydrates made from, which makes them different from proteins?
Complex carbohydrates, unlike proteins, are usually made up of the same monomers
What is eliminated when simple sugars polymerise?
A H2O molecule is eliminated when simple sugars polymerise
What linkage is formed when simple sugars polymerise?
The linkage formed is an -O- linkage called a glycosidic linkage
What process can complex carbohydrates undergo to produce the monomers they were made from?
The complex carbohydrates also undergo hydrolysis and produce the simple sugar monomers from which they were made
How can complex carbohydrates be hydrolysed?
This can be done by refluxing with more moderately concentrated HCl
- What is produced by fermenting simple sugars?
Fermentation of simple sugars
Simple sugars can be fermented to produce alcohol
- What are simple sugars dissolved in and in what conditions?
Fermentation of simple sugars
They are dissolved in water and yeast is added to be fermented between 15 and 35°C in the absence of oxygen for a few days
- How does temperature affect the rate of reaction during the fermentation of simple sugars?
Fermentation of simple sugars
If the temperature is too low the reaction rate will be too slow and if it is too high the enzymes will become denatured
- What type of enzymes does yeast contain?
Fermentation of simple sugars
Yeast contains zymase enzymes (biological catalysts) that break down starch or sugar to glucose
- In what ways does yeast respire due to a lack of oxygen and what does it produce?
Fermentation of simple sugars
The yeast respires anaerobically using the glucose to form ethanol and carbon dioxide
- What is the chemical equation for the anaerobic respiration of yeast?
Fermentation of simple sugars
C6H12O6 + Enzymes → 2CO2 + 2C2H5OH
- How can chromatography be useful in the hydrolysis of carbohydrates and proteins?
(chromatography and the hydrolysis of carbohydrates and proteins)
The identification of the products of the hydrolysis of carbohydrates and proteins can be done using chromatography
- The products of the hydrolysis of carbohydrates and proteins are colourless. How can chromatography still be used?
(chromatography and the hydrolysis of carbohydrates and proteins)
Both carbohydrate and protein monomers are colourless so locating agents must be used
- What type of chromatography is used and why?
chromatography and the hydrolysis of carbohydrates and proteins
A technique called 2-Dimensional paper chromatography is used as some simple sugars and amino acids have the same Rf value
- how does 2-dimensional paper chromatography work?
chromatography and the hydrolysis of carbohydrates and proteins
In this technique a run is carried out in one direction, then the paper is rotated by 90º and performed again using a different solvent
- Why is 2-dimensional paper chromatography useful?
chromatography and the hydrolysis of carbohydrates and proteins
This further separates sample spots that may not have separated in the first run
- What is done with the final chromatogram?
chromatography and the hydrolysis of carbohydrates and proteins
The resulting chromatogram is dried and sprayed with a locating agent
- How are the products identified?
chromatography and the hydrolysis of carbohydrates and proteins
The Rf value of each solvent used is characteristic for each sugar or amino acid
Hydrocarbons
A compound containing only Hydrogen and Carbon.
Alkanes
Saturated Hydrocarbons
-ane
H(n)C(2n+2)
Stem names 1-5
Meth-
Eth-
Prop-
But-
Pent-
Properties of short chain hydrocarbons
> Low boiling point
High volatility
Low viscosity (V runny)
Burn without a smoky flame.
Properties of long chain hydrocarbons
> High boiling point
Low volatility
High viscosity (not runny)
Burn with a smoky flame
Fractional Distillation
A way to separate liquids from a mixture of liquids by boiling off the substances at different temperatures, then condensing them and collecting the liquids.
What is the temperature range of a fractionating column?
350-50 degrees.
Is short or long chain hydrocarbons better as fuels?
Short.
Oxidation reaction
When oxygen is added to a substance (or when electrons are lost).
Reduction reaction
When a oxygen is removed from a substance (or when electrons are gained).
Alkane + Oxygen ->
Carbon Dioxide + Water
Sulfur Dioxide
A toxic gas (formula SO2) that causes acid rain.
How does carbon dioxide contribute to climate change?
A
It absorbs radiation which has been emitted from the surface of the earth as energy, causing it to remain in the atmosphere.
Incomplete combustion
When a fuel burns in insufficient oxygen, producing carbon monoxide as a toxic product.
How does CO kill humans?
It is picked up by red blood cells instead of Oxygen. It is colourless and odourless.
Nitrogen Oxides
Gaseous pollutant given off by motor vehicles; a cause of acid rain.
Particulates
Small solid particles of carbon and hydrocarbons given off from motor vehicles as a result of incomplete combustion of their fuel.
Global Dimming
The reflection of sunlight back into space, caused by particulates. Possible cause of cancer.
Advantages of biofuels
> Less harmful if spilled.
Burns more cleanly (Less particulates emitted).
Will become cheaper as resources dwindle.
Plants absorb CO2 as they grow, making biofuels ‘carbon dioxide neutral’. (CO2 still used in fertilisation, harvesting, extracting and processing, and transportation).
Disadvantages of biofuels
> Use farmland, so less is available for crop production.
> Could result in famine, deforestation and species becoming extinct as their habitats are destroyed.
Fermentation
The reaction in which enzymes in yeast turn glucose into ethanol and carbon dioxide.
Fermentation Reaction
Glucose -> Ethanol + Carbon Dioxide
C6H12O6 -> 2C2H5OH + 2CO2
Why is hydrogen a good potential source of power?
It reacts to produce water; it is clean and environmentally friendly.
Cracking
The reaction used to break down large unusable hydrocarbons into smaller, more useful ones.
Conditions for cracking
Passed over a hot catalyst/ mixed with steam
Heated to a high temperature (e.g. 500 degrees)
Alkenes
Unsaturated hydrocarbons which contain carbon-carbon double bonds. General formula CnH2n
Test for alkenes/ unsaturated carbon-carbon double bonded molecules
Bromine water turns from orange to colourless.
Hydration
A reaction in which water is chemically added to a compound.
What is produced by cracking?
alkanes to be used as fuel, and alkenes.
Monomers
Small reactive molecules that react together in repeating sequences to form a very large molecule (a polymer).
Properties of poly(ethene)
> Easy to shape
Strong
Transparent
Properties of poly(propene)
> Strong
> Tough
Polymerisation
When alkene molecules join together as the double bond between the carbon atoms ‘opens up’ and the thousands of molecules are able to join together.
What do the properties of a polymer depend on?
> The monomers used to make it.
> The conditions chosen to carry out the reaction.
Low Density poly(ethene)
> Formed using high pressure and trace oxygen.
> Polymer chains are joined together at random and they can’t pack together, hence its lower density.
High Density poly(ethene)
> Formed using a catalyst at 50 degrees with a slightly raised pressure.
Creates straight, closely packed chains that give it a higher density.
It is stronger and less prone to melting that LD poly(ethene).
Thermosoftening Polymers
Polymers that form plastics which can be softened by heating, then remoulded into different shapes as they cool down and set.
Thermosetting Polymers
Polymers that can form extensive cross-linking between chains, resulting in rigid materials which are heat resistant.
What sort of bonds are used in polymer chains?
Very strong covalent bonds.
Bonding in Thermosoftening Polymers
> Forces between the polymer chains are weak, and broken by heating.
When the polymer cools down again, it is brought back together by intermolecular forces.
Bonding in Thermosetting Polymers
> Monomers create covalent bonds between the polymer chains when it is forms to create its shape and structure.
Covalent bonds are strong, and stops the polymer from melting or changing shape.
Polymer will not melt, will char instead at high enough temps.
Which is more reactive- alkanes or alkenes?
The C-C double bond in alkenes make them much more reactive.
Smart Polymers
Polymers that change in response to changes in their environment.
2 ways to speed up the decomposition of polymers:
> Building cornstarch molecules into the plastic allows the microorganisms in soil to break up the plastic more quickly.
Polymers are being made from plant material.
Alcohols Functional Group
-O-H
Carboxylic Acid Functional Group
-C=O-O-H
Ester Functional Group
-C=O-O (CH)
Ethanol + Oxygen =
Carbon Dioxide + Water
What happens when sodium reacts with alcohols?
> The reaction is similar to that of water, but less vigorous.
In ethanol the solution formed is sodium ethoxide.
Emits hydrogen.
Ethanol + Oxygen atoms from an oxidising agent =
Ethanoic acid + Water
Difference between strong and weak acids.
Strong acids ionise completely in water.
Strong acids therefore have a higher concentration of H+ ions in their solution.
What 3 things are needed to make an ester?
> Alcohol
Carboxylic Acid
A strong acid catalyst.
Carboxylic Acid + Alcohol =
Ester + Water
Properties of esters
> Volatile
Smell distinctive
Used in perfumes and food flavourings.
What is a homologous series?
group of organic compounds with the same functional group and similar properties
What is a functional group?
atom/group of atoms that gives an organic compound its particular chemical properties (e.g. -OH, -COOH)
What are structural isomers?
compounds with the same molecular formula but different structural formula that can be straight-chained or branched
What are hydrocarbons?
compound containing carbon and hydrogen only
What is a saturated hydrocarbon?
hydrocarbon contain only single covalent bonds between carbon atoms
Prefixes of 1-4 carbon atoms
meth, eth, prop, but
Name the three fuels
coal, natural gas, petroleum
What is the main constituent of natural gas?
methane
What is petroleum?
A mixture of hydrocarbons
How is petroleum separated?
Fractional distillation
Name the eight fractions of petroleum
refinery gas, gasoline, naphtha, kerosene, diesel oil, fuel oil, lubricating fraction, bitumen
What is the use of refinery gas?
Bottled gas for heating and cooking
What is the use of gasoline?
Petrol in cars
What is the use of naphtha?
Making chemicals
What is the use of kerosene/paraffin?
Jet fuel
What is the use of diesel oil?
Fuel in diesel engines
What is the use of fuel oil?
Fuel for ships and home heating systems
What is the use of lubricating fraction?
Lubricants, waxes and polishes
What is the use of bitumen?
Making roads
What is the general formula for alkanes?
CnH2n+2
Describe the bonding in alkanes
Molecules contain only single bonds between carbon atoms in the chain
Describe the trend in boiling points for alkanes
Carbon chain gets longer, boiling points increase
What are the conditions for alkanes to react with chlorine?
Sunlight/light
What happens during a chlorine/alkane reaction?
A chlorine atom replaces a hydrogen atom
What is the general formula for alkenes?
CnH2n
What is the functional group of alkenes?
C=C bond
What is cracking?
Thermal decomposition reaction, in which an alkene is produced from an alkane
What are the conditions of cracking?
Catalyst (aluminium oxide + silicon (IV) oxide), high temperature
What happens to the molecules during cracking?
Large hydrocarbon molecules are broken down to smaller ones and alkenes
What are two differences between saturated and unsaturated hydrocarbons?
Double bond difference, reaction in bromine water (red/orange vs colourless)
What is a polymer
large molecules built up from monomers
How is polythene produced?
Addition polymerization
How is polythene produced?
Addition polymerization
What happens during the addition polymerization of polythene?
Double bond splits and polymer is formed
What do alkenes form when they react with steam under heat, pressure and a catalyst?
Alcohol
What is the general formula for alcohols?
CnH2n+1 OH
What is the functional group of alcohols?
OH
What are the two ways alcohol is manufactured?
Fermentation & Catalytic addition of steam to ethene
Describe the process of fermentation (3)
- Enzymes in yeast break down glucose to ethanol and carbon dioxide, giving out heat
a) Can be done with substances that contain cellulose, starch or glucose
b) Done by grinding source (e.g. grapes) and adding enzymes to break down cellulose and starch into glucose. - Leave it to ferment.
- Fractional distillation is used to get ethanol from the mixture
How is ethanol separated from the mixture during fermentation?
Fractional distillation
Describe the process of catalytic addition to steam and ethene + conditions (3)
- Ethene is obtained by cracking long-chain alkanes from oil
- The ethene reacts with steam (reversibly) in the following conditions:
- 570°C
- 60-70atm
- Catalyst = phosphoric acid - Low temperature gives a better yield, but high temperature is used to give a better rate of reaction
What is the temperature needed in catalytic addition to steam and ethene?
570°C
What is the pressure needed in catalytic addition to steam and ethene?
60-70atm
What is the catalyst needed in catalytic addition to steam and ethene?
Phosphoric acid
What are two advantages of fermentation?
Renewable source
Good use of waste organic material
What are two disadvantages of fermentation?
Fractional distillation expensive
Slow process
What are two advantages of catalytic addition to steam and ethene?
Fast, continuous process
Ethanol is pure
What are two disadvantages of catalytic addition to steam and ethene?
Oil is a non-renewable resource
Lots of energy required to get conditions
Describe the burning of ethanol
Ethanol burns well in oxygen, giving out heat, carbon dioxide and water
Two uses of ethanol
Solvent and fuel
Why is ethanol used as a solvent?
to dissolve things than water cannot. Evaporates easily, so used as solvent in glues, printing inks & perfumes
Why is ethanol used as a fuel?
added to or instead of petrol, because it burns cleanly
What is the general formula of carboxylic acids?
CnH2n+1COOH
What is the functional group of carboxylic acids?
COOH
What are the properties of ethanoic acid?
Weak acid with high pH and low dissociation
How is ethanoic acid formed? (2)
Oxidation of ethanol:
in air
by fermentation with acidified potassium permanganate
What monomers react together in esterification?
Carboxylic acid + alcohol
What are the products of esterification?
Ester + water
What does esterification happen in the presence of?
Catalyst (e.g. sulfuric acid)
Esterification is ____ reaction
reversible
Formation of ethyl ethanoate
Ethanoic acid + ethanol ⇌ ethyl ethanoate + water
What are polymers?
large molecules built up from small units (monomers)
What are some uses of poly(ethene)?
plastic bags, gloves, bowls, dustbins
What are some uses of poly(propene)
crates, ropes
What are some uses of polyvinylchloride (PVC)
rainwater pipes, gutters, insulation around electrical wires
What are some uses of nylon?
ropes, clothes, fishing nets
What are some uses of terylene?
clothing
What monomers are addition polymers made of?
Unsaturated monomers (such as alkenes)
What reaction produces condensation polymers?
condensation reaction
What monomers are condensation polymers made of?
molecules of two monomers usually used
What monomers are addition polymers made of?
usually many molecules of a single monomer
What reaction produces addition polymers?
an addition reaction
What happens during an addition reaction?
monomers join together by opening the C=C double bond
What product(s) are formed from an addition reaction?
only a single product – the polymer
What product(s) are formed from a condensation reaction?
two products – the polymer plus water (by product)
How reactive are addition polymers to acids?
resistant to acids
How reactive are condensation polymers to acids?
hydrolysed by acids
Are addition polymers biodegradable/non-biodegradable?
non-biodegradable
Are condensation polymers biodegradable/non-biodegradable?
biodegradable
What reaction produces polyesters and polyamides?
condensation reaction
What happens during a condensation reaction?
Monomers join to form a polymer and a small molecule is eliminated
What happens during a condensation reaction?
Monomers join to form a polymer and a small molecule is eliminated
Is nylon a polyamide/polyester?
polyamide
What are the monomers that form polyamides?
carboxylic acids + amines
What type of linkage do polyamides have + draw the linkage
amine linkage (C=O-N-H)
What is the functional group of an amine compound?
NH2
Describe the bond forming in the production of polyamides? (Double bonds/Single bonds breaking/forming)
No double bonds break, instead single bonds break, and new single bonds form
What is eliminated in the formation of polyamides?
hydrogen chloride
What is formed as a by-product in the formation of polyamides?
water
Draw the structure of nylon
C-N-H and N-H-C alternating (C with double bonds)
Is terylene a polyamide/polyester?
polyester
What are the monomers that form polyesters?
carboxylic acids + alcohols
What type of linkage do polyesters have + draw the linkage
Ester linkage (C=O-O)
What molecule is eliminated in the formation of polyesters?
water molecule
Draw the structure of terylene
C-O and O-C alternating (C with double bonds)
What is a hydrogenation reaction?
The addition of hydrogen to a compound - reacts with alkenes to form alkanes
What are the conditions required for a hydrogenation reaction occur?
60 degrees C
nickel catalyst
What happens to the bonding in hydrogenation reactions?
Alkene double bonds break down to single bonds
What are three common addition reactions?
The reaction of alkenes with bromine
Hydrogenation
Steam reacts with alkenes to form alcohols
What is the general formula of carboxylic acids?
CnH2n+1COOH
What is the functional group of carboxylic acids?
COOH
What are the properties of ethanoic acid? (3)
Weak acid
high pH
low dissociation
How is ethanoic acid formed? (2)
Oxidation of ethanol:
in air
by fermentation with acidified potassium permanganate
What are acetobacter?
bacteria naturally present in air
What happens when we leave a solution of ethanol exposed to air?
Enzymes from the bacterium speed up the conversion of ethanol to ethanoic acid
What does the oxidation of ethanol in air not take place without?
does not take place in the absence of oxygen
What is the word equation for the oxidation in air of ethanol to ethanoic acid?
ethanol + oxygen => ethanoic acid + water
What is the symbol equation for the oxidation in air of ethanol to ethanoic acid?
C2H5OH + 2[O] → CH3COOH + H2O
Why do we write [O]?
the oxidation reaction is complicated but oxygen is involved
Describe the oxidation in air of ethanol to ethanoic acid (3)
- Solution of ethanol is exposed to air
- Bacterium speed up conversion of ethanol to ethanoic acid
( C2H5OH + 2[O] → CH3COOH + H2O ) - Reaction makes vinegar, vinegar is solution of ethanoic acid
Describe the oxidation of ethanol with acidified potassium manganate (VII)
- Heat ethanol with potassium manganate and sulfuric acid in a flask with a condenser in an upright position (refluxing)
C2H5OH + 2[O] → CH3COOH + H2O - Ethanoic acid is formed
Why do we use a condenser in the oxidation of ethanol with acidified potassium manganate (VII)?
Alcohol is volatile - prevents escaping
What is a functional group?
atom or group
of atoms that determine the chemical properties
of a homologous series
state the formula of alkanes
CnH2n+2
State the fomula of alkenes
CnH2h
State the formula of alcohols
CnH2N+1OH
State the formula of Carboxylic acids
CnH2n+1COOH
what is a structural formula?
unambiguous description of the way the atoms
in a molecule are arranged
What are structural isomers?
compounds with the
same molecular formula, but different structural
formulae
What is a homologous series?
a family of similar compounds with similar chemical
properties due to the presence of the same
functional group
Describe the general characteristics of a
homologous series
-same functional group
-same general formula
-differing from one member to the next by a –CH2– unit
- displaying a trend in physical properties
-sharing similar chemical properties
Do saturated compounds have a single bond or double bond? Give an example
Single, carbon-carbon bond
alkANES, Ethane
Do unsaturated compounds have a single bond or a double bond? Give an example
Double carbon=carbon
AlkENES, Ethene
Name three fossil fuels?
coal, natural gas and
petroleum
What is the main consituent of natural gas?
Methane, CH4
What are hydrocarbons?
coumpounds containing hydrogen and carbon ONLY
What is petroleum a mixture of?
Hydrocarbons and natural gas
How can petroleum be separated from fossil fuels?
by fractional disstillation
What is substitution of atoms?
one atom or group of atoms is replaced by another atom or
group of atoms
What is a fuel?
substance that when burnt releases energy
How does petroleum look and where can we find it?
thick sticky and black
found under the sea and under the ground
Why do we use fractional distillation to separate petroleum’s fractions?
Petroleum by itself isn’t very useful, but each component part of the mixture (called fraction) can be
since they have different boiling points, fractional distillation can be used to separate them
What do the molecules in each fraction have in similar?
similar chemical properties and b.P
How do shorter alkanes act with oxygen?
they’re flammable and evapourate easily
How do longer alkanes act with oxygen?
they’re viscous meaning sticky or honey like
Where is fractional distillation carried in?
in a fractionating column
What happens when crude oil enters the fractionating column?
it is heated and vapour rises
What with happen with the vapors that have a high boiling point?
they will immediately turn into liquid and be tapped off
What happens with the vapors that have low boiling points?
they will rise up and will condense (at the top of the fractionating colum) and then be tapped off
different fractions condense on different heights in the fractionating column according to what?
their boiling points
where are the substances with low boiling points collected?
at the top
Where are the substances with high boiling points collected?
at the bottom
Explain the viscosity of hydrocarbons in terms of chain length
If carbon number increases, the attraction between carbons is much higher and harder to break the bond in the molecules.
=more viscosity as chain length increases
Explain the b.p in terms of chain length
as chain length increases; molecules get larger and intermolecular forces of attraction between each other are greater= harder to break the bonds( in need of more energy)
Explain the volatily of hydrocarbons in fractional distillation
in terms of their chain length
become less volatile as molecular size increase in length
this is because forces of attraction increase as molecular size increases
define viscosity
ease of flow of liquid
define volatile
tendency of substance to vaporize
Describe petroleum and its separation into useful fractions by fractional distillation
Petroleum is also called crude oil and is a complex mixture of hydrocarbons which also contains natural gas.
The fractionating column is hot at the bottom and cool at the top.
Crude oil enters the fractionating column and is heated so vapours rise.
Vapours of hydrocarbons with very high boiling points will immediately turn into liquid and are tapped off at the bottom of the column.
Vapours of hydrocarbons with low boiling points will rise up the column and condense at the top to be tapped off.
The different fractions condense at different heights according to their boiling points and are tapped off as liquids.
The fractions containing smaller hydrocarbons are collected at the top of the fractionating column as gases.
The fractions containing bigger hydrocarbons are collected at the lower sections of the fractionating column.
Name the uses of the fractions
(In order from top to bottom)
refinery gas for bottled gas for heating and cooking
gasoline for petrol in cars
naphtha for making chemicals
kerosene/paraffin for jet fuel
diesel oil/gas oil for fuel for diesel engines
fuel oil for fuel for ships and home heating
lubricating oil for lubricants, waxes and polishes
bitumen for making roads
the compounds in a homologous series have the same…
general formula
Describe substitution reactions of alkanes with chlorine
In a substitution reaction, one atom is swapped with another atom. Alkanes undergo a substitution reaction with halogens in the presence of ultraviolet radiation.
In the presence of ultraviolet (UV) radiation, methane reacts with chlorine in a substitution reaction.
CH₄ + Cl₂ → CH₃Cl + HCl
Chloromethane is formed.
Distinguish between saturated and unsaturated hydrocarbons:
- by reaction with aqueous bromine
Bromine water is an orange coloured solution of bromine.
When bromine water is shaken with an Alkane, it will remain as an orange solution as alkanes do not have double carbon bonds (C=C) so the bromine remains in solution.
But when bromine water is shaken with an alkene, the alkene will decolourise the bromine water and turn colourless as alkenes do have double carbon bonds (C=C).
The bromine atoms add across the C=C double bond hence the solution no longer contains the orange coloured bromine.
What are substitution reactions
substitution reaction one atom or
group of atoms is replaced by another atom or
group of atoms
Alcahols can be _____ to form carboxylic acids
oxidised
state the chemical properties of alcohol
flammable
soluble
homologous series
can be oxidised to form carboxilic acids
describe the complete combustion of ethanol
ethanol+oxygen-> carbon dioxide+water
manifacture of ethaol by hydration of ethene by steam
hydration of ethane by steam in presence of phospheric acid
- 300 degrees and 60 atm
c2H4+H20->Ethanol or C2H5OH
manufacture of ethanol by fermentation of yeast by anerobic respiration
glucose->in presence of yeast-> ethanol+CO2
25-35 degrees
in abstence of O2
advantages of manufacturing ethanol by fermentation
renewable
cheap
disadvantages of manufacturing ethanol by fermentation
unpure ethanol
slower than with steam
slow
can’t do it over 35 degrees otherwise denaturing will happen
advantages of manufacturing ethanol by steam
cheap
pure
efficient
fast
disadvantages of manufacturing ethanol by steam
non renewable
takes a lot of energy
what can ethanol be used as
solvent and fuel because it is very flammable
Describe the formation of ethanoic acid by the
oxidation of ethanol:
with acidified aqueous potassium
manganate(VII)
by bacterial oxidation during vinegar
production
Describe the reaction of a carboxylic acid with an
alcohol using an acid catalyst to form an ester
When a carboxylic acid is treated with an alcohol and an acid catalyst, an ester is formed
Define polymers
large molecules built up from
many smaller molecules called monomers
Describe the formation of poly(ethene)
it’s an example of addition polymerisation using ethene
monomers
describe the structure of nylon
c-n-h bond
describe the structure of PET
c=O=O bond
state something about PET
PET can be converted back into
monomers and re-polymerised
plastics are made from ?
polymers
Describe how the properties of plastics have
implications for their disposal
they can become mixed with other chemicals or materials if they are not recycled properly which just pollutes the world and makes recycling more difficult.
it’s unbiodegradable meaning that both microorganisms and bacteria can’t break it down so it just keeps on accumulating causing pollution as well as if it’s burned it causes co2 contributing to greenhouse effect
Describe the environmental challenges caused by
plastics
(a) disposal in land fill sites
(b) accumulation in oceans
(c) formation of toxic gases from burning
Describe proteins
natural polyamides and that
they are formed from amino acid monomers
What does the R represent in a protein structure
represents different types of side chain
State what a structural formula is
an unambiguous description of the way the atoms
in a molecule are arranged
Define structural isomers
compounds with the same molecular formula, but different structural formulae
what is the substitution reaction of an alkane with chlorine described as?
described as photochemical
what presence do we need for substitution of alkanes to take place with chlorine
uv
What are the six polyatomic ions?
Ammonium.
Carbonate.
Sulfate.
Hydroxide.
Nitrate.
Phosphate.
What are the chemical names for the six diatomic molecules?
Ammonium - NH₄⁺.
Carbonate - CO²⁻ ₃
Sulfate - SO₄²-.
Hydroxide - OH¯.
Nitrate - NO⁻ ₃.
Phosphate - PO₄³⁻.
What are the seven diatomic molecules?
Oxygen. O₂.
Chlorine Cl₂.
Nitrogen N₂.
Iodine I₂.
Bromine Br₂.
Fluorine F₂.
Hydrogen H₂.
In what circumstance does an element become a diatomic molecule?
When it reacts on its own.
FOR EXAMPLE - C + O₂ → 2CO.
State the method used to crack crude oil
Fractional distillation
Why does crude oil go through cracking?
To break long chains of useless hydrocarbons into smaller useful hydrocarbons
Name the products of the fractional distillation of crude oil going from the lowest number of carbons.
State the approximate temperatures the fractions are condensed at
State the number of carbons within each fraction
Refinery gases (C1-C4) = 25 degrees C
Gasoline (petrol) (C6-C8) = 40 degrees C
Naphtha (C6-C8) = 100 degrees C
Kerosene (Paraffin) (C11-C15) = 190 degrees C
Diesel oil (C16-C20) = 250 degrees C
Fuel oil (C20-C30) = 330 degrees C
Bitumen (C50+) = 350 degrees C
Use of:
1-Refinery gases
2-Gasoline
3-Naphtha
4-Kerosene (Paraffin)
5-Diesel oil
6-Fuel oil
7-Bitumen
1-Bottled gas
2-Fuel for cars
3-Making chemicals
4-Aircraft oil
5-Fuel for cars e.g. lorries and buses
6-Fuel for ships, ferries, power stations
7-Roads and roof construction
For hydrocarbons with a low boiling point and a high boiling point - Crude oil
Volatility
Ignition
Ability to flow (Viscosity)
LOW BOILING POINT:
Very volatile
Ignites easily
Flows easily
HIGH BOILING POINT:
Not very volatile
Doesn’t ignite easily
Doesn’t flow easily
General formula for:
1-Alkanes
2-Alkenes
3-Alcohols (and the functional group)
1-CnH2n+2
2-CnH2n
3-CnH2n+1OH
Functional group = OH
Describe an experiment to explain catalytic cracking
Catalyst = normally silicon dioxide or porcelain chips which contain Al2O3
1-Heat a boiling tube that contains mineral wool soaked in one end of the the boiling tube. The catalyst is placed in the toiling tube but it doesn’t touch the mineral wool.
2-The gas released is collected over water.
3-You always make ethene along with others.
Test for a C=C bond?
Use aqueous bromine water which is orange. It will turn colourless if there is a C=C bond present
What type of reaction are these and what are the products of the reactions:
1-Bromination
(Mention haloalkanes)
2-Hydrogenation
3-Hydration
1-Addition of Br2 molecule. Add a Br2 molecule to the alkene to produce a dibromoalkane.
Halogen molecule + Alkene –> Haloalkane
2-Adding hydrogen to an alkene to make an alkane
3-Adding water to an alkene to make an alcohol
Conditions for hydrogenation
Catalyst: Nickel
Temperature: 200 degrees C
Pressure: 200 atm
Conditions for hydration
Catalyst: Phosphoric acid
Temperature: 300 degrees C
Pressure: 60 atm
Equation for:
1-Complete combustion of alkanes?
2-Incomplete combustion of alkanes?
1-ALKANE + O2 –> CO2 + H2O + heat
2-ALKANE +O2 –> CO + H2O + heat
Alcohols will undergo ____ when in the presence of which 2 catalysts?
Oxidation
Catalysts: Potassium dichromate and concentrated sulphuric acid
2 ways of which Ethanol is formed?
State the conditions and describe each method.
Pros/cons
1-FERMENTATION
Uses corn, sugar cane, rice (renewable)
30-40 degrees C
Continuous process
Slow reaction
Low percentage yield/impure = 15%
Produces 15% of CO2 for every 15% of ethanol produced
Cheap
1-HYDRATION OF ETHENE
Crude oil (non renewable)
300 degrees C and 60 atm
Batch process
Fast reaction
High percentage yield/pure = 99%
Expensive
1-How are carboxylic acids made?
2-How are esters made?
Type of reaction?
1-Oxidisation of alcohol in the presence of potassium dichromate and sulphuric acid e.g. Ethanol to ethanal to ethanoic acid
2-Reacting an alcohol and carboxylic acid together. Condensation reaction.
Name the process of making esters
Esterification
How do you break the ester back into it’s alcohol and carboxylic acid?
Hydrolysis of esters.
React the ester with either a concentrated acid or concentrated alkali
e.g. HCl or NaOH
How to identify esters
Esters have a distinctive smell, usually pleasant.
Esters - Solubility in water?
Esters that have shorter chains are fairly soluble in water.
Solubility decreases as the length of the ester increases.
Conditions for oxidising an alcohol
Potassium dichromate and sulphuric acid
1 atmosphere
50 degrees C
Define addition polymerisation and condensation polymerisation
Addition polymerisation = A chemical reaction in which a polymer is formed from the adding together of many monomer molecules
Condensation polymerisation = The joining together of many of two different monomer molecules to form one single long molecule (polymer) during which a small molecule is removed (condensed). This is usually water
Example and use of:
1-Natural polymer
2-Synthetic polymer
1-Protein (made from amino acids) - hair, bones, teeth…
2-Nylon -clothes
Example of an addition polymer and it’s use
Poly(styrene)
- Fast food cartons and other food packaging
Macromolecules in food (3)
1-CARBOHYDRATES - contain carbon, oxygen and hydrogen. Monosaccharide (has a single sugar unit). Made of glucose
2-CELLULOSE - It’s a polysaccharide and is made up of glycogen (a complex carbohydrate)
3-PROTEIN - Made up of amino acids
4-FATS - They’re not polymers. They are esters. Formed by reacting 3 molecules of a fatty acid with 1 molecule of glycogen
Uses of Polythene
(low/high density)
(3 each)
LOW DENSITY:
Plastic bags
Gloes
Clingfilm
HIGH DENSITY:
Mugs
Bowls
Chairs
Uses of Polychloroethene (PVC)
3
Water pipes
Wellingtons
Hoses
Uses of Teflon
3
Coating frying pans to make then non stick
Fabric protector
Flooring
Uses of Nylon
3
Ropes
Fishing nets and lines
Clothes
Uses of Terylene
2
Clothing (especially when mixed with cotton)
- Thread
Polythene and pollution?
4
Plastic bags are left as litter
Non biodegradable (can not be broken down by bacteria)
Animals are unable to digest plastic
Clog drains and sewers causing flooding
Future for polymers?
Give an example.
BIO-POLYMERS:
-Grown in plants or made in tanks by bacteria
E.G
1-Plants that can produce plastic already exist. The part of the cells that made the plastic will be extracted when the plants are harvested. Plastic is extracted using a solvent which is then evaporated off afterwards
2-One strain of bacteria can feed on sugar from crops such as maize, to produce polyesters
Define hydrolysis
Hydrolysis = A chemical reaction in which molecules are broken down by reaction with water
Hydrolysis of protiens
What does the complete hydrolysis of proteins give you?
Boil with 6M HCl for 24 hours
Amino acids
1-Hydrolysis of starch (conditions)
2-What does the complete hydrolysis of starch give you?
3-What does incomplete hydrolysis of starch give you?
1-Heat with dilute HCl
2-Glucose
3-Mixture of different molecules. Maltose (2 glucose units) and maltotriose (3 glucose units) and dextrins (many glucose units)
Hydrolysis of fats
What does the complete hydrolysis of fats give you?
Boil with dulite NaOH
Glycerol + sodium salts of the fatty acid
How to identify what you have produced after hydrolysis?
Chromatography
Solutions will be colourless.
Use PENCIL to draw a line across the bottom of the chromatography.
Place a drop of each solution at the bottom of a piece of chromatography.
Place a solvent a the bottom of a beaker and place the bottom of the chromatography paper into the solvent. The pencil line and solution must not touch the actual solvent.
Use pencil to mark where the solvent ends on the paper.
Net spray it with a locating agent e.g. Minhydrin
Define thermal decomposition
The breaking down of a compound in the presence of heat
What does it mean when a compound is thermally stable?
It is resistant to thermal decomposition
