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