c6 organic chemistry Flashcards
what is crude oil?
a finite resource found in rocks. its a mixture of very large compounds. it is also the remains of an ancient biomass consisting mainly of plankton that was buried in mud
what are most of the compounds that are found in crude oil?
hydrocarbons called alkanes
what are the members of alkanes and how many carbons do they have?
methane- 1
ethane- 2
propane- 3
butane- 4
pentane- 5
hexane- 6
what are alkanes?
a homologous series (group of compounds that react in a similar way)
are alkanes saturated or NON saturated hydrocarbons?
saturated hydrocarbons- each carbon atom forms 4 covalent bonds
what can hydrocarbons be separated into?
they can be separated into fractions, which contain molecules with a similar number of carbon atoms
how can hydrocarbons be separated?
through fractional distillation
what can be done to fractioned compounds to make them useful?
they can be processed to produce fuels and livestock for the petrochemical industry
which fuels are made from crude oil?
- petrol
- diesel oil
- kerosene
- heavy fuel oil
- liquefied petroleum gas
what useful materials in our daily lives are produced by the petrochemical industry?
- solvents
- lubricants
- polymers
- detergents
why do the vast array of natural and synthetic carbon compounds occur?
due to the ability of carbon atoms to form families of similar bonds
describe how fractional distillation works
1) the oil is heated until most of it turns into gas
2) in the column, there is a temperature gradient (hot at the bottom, cooler as u go up)
3) the longer chains have high BPs, so they condense and drain out and turn back into liquids very early on, near the bottom. the opposite happens to shorter chains who have lower BPs who condense and drain out later on, near the top.
4) so therefore we end up with crude oil mixtures separated out into different fractions
what do some of the properties of hydrocarbons depends on?
and what do they influence?
- example
- size of their molecules
- boiling point
- viscosity
- flammability
they influence how hydrocarbons are used as fuels
EG: shorter chains with lower BPs are used as ‘bottled gasses’
how does the length of a hydrocarbon chain influence it’s viscosity?
VISCOSITY- how gloopy it is
the shorter the chain, the less viscous it is.
the longer the chain, the more viscous it is.
how does the length of a hydrocarbon chain influence it’s volatility?
VOLATILITY- how easily a substance can evaporate
the shorter the chain, the more volatile it is.
the longer the chain, the less volatile it is.
how does the length of a hydrocarbon chain influence it’s flammability?
FLAMMABILITY- how easily it can ignite
the shorter the chain, the more flammable it is.
the longer the chain, the less flammable it is.
when does complete combustion occur?
when there is plenty of oxygen
what does complete combustion of any hydrocarbon release?
energy
what is the word equation for complete combustion?
hydrocarbon + oxygen= (energy) + carbon dioxide + water
what happens during complete combustion?
both carbon and hydrogen from the hydrocarbon are oxidised. they GAIN oxygen
why can hydrocarbons be used as fuels?
because of the amount of energy released when they combust completely
what can be done to hydrocarbons to produce smaller, more useful molecules?
they can be cracked
what are some different methods of cracking?
catalytic cracking and steam cracking
what is cracking?
cracking is a thermal decomposition reaction
how does catalytic cracking happen?
1) heat long chain hydrocarbons to vaporise them.
2) then the vapour can be passed over a hot powered aluminium oxide catalyst.
3) the long chain molecules split apart on the surface of the specks of calalyst
what are the general conditions for cracking?
steam
high temperatures
high pressure
heated catalyst (for catalytic)
what are the products of cracking?
alkenes
whats the reactive difference between alkanes and alkenes
alkenes are more reactive
what is the test for alkenes and what is the positive result? what is the negative result?
bromine water.
a) POSITIVE result- bromine turns from orange liuid to colourless liquid as it takes the place of the missing hydrogen atoms
b) NEGATIVE result- no colour change. as this means that it is an alkane and they are already saturated
why can some of the products of cracking be useful?
some of the products of cracking can be useful as fuels
because there is a high demand of fuels with smaller molecules
what are alkenes used for?
for the production of polymers as starting materials for the production of many other chemicals
what are alkenes?
unsaturated hydrocarbons because the have a C=C bond
what is the general formula of alkenes?
Cn H2n
explain WHY alkenes are unsaturated?
the C=C bond means that alkenes have two fewer hydrogens compared with the alkanes.
what are the different types of alkene reactions?
- combustion reaction
- addition reaction
(hydrogenation reaction)
(reaction with bromine water)
(reaction with steam)
describe the combustion reaction with alkenes
- can go through both complete and incomplete combustion.
- when burning them in air they tend to go through incomplete combustion.
- products of this incomplete combustion is water, CO2 and carbon monoxide
- incomplete combustion results in smoky yellow flame and less energy
conditions for combustion? (alkanes and alkenes)
for INCOMPLETE: little oxygen
for COMPLETE: plenty oxygen
what is a functional group?
a group of atoms in a molecule that determines how that molecule typically reacts
what happens in addition reactions with alkenes regarding their C=C bond?
their C=C bond will open up to leave a single bond and a new atom is added to each carbon
what will happen to an alkene during hydrogenation?
what are the conditions for hydrogenation?
1) the hydrogen will react with the double-bonded carbons to open up the double bond and form the equivalent, saturated, alkane.
2) a catalyst is needed
what happens in an addition reaction between an alkene and halogen?
what are the conditions?
1) the halogen atom will partially break the C=C bond to a single bond then bond with each carbon atom
2) light and high temperatures
what happens in the addition reaction between an alkene and steam (water)?
what are the conditions?
1) the C=C partially breaks and water is added to the unbonded atoms. this creates an ALCOHOL
2) high temperatures
what is done AFTER the reaction of water and alkene takes place?
the reaction mixture is passed on from the reactor to the condenser, and any unreacted alkene gas is recycled back to the reactor. the alcohol ccould then be purified from the mixture by fractional distillation
what functional group do alcohols contain?
-OH
what is the general formula of alcohols?
Cn H2n+1 OH
what are the first 4 alcohols in the homologous series?
methanol
ethanol
propanol
butanol
what are the properties of the first 4 alcohols in the homologous series?
1) all alcohols are flammable, they can undergo combustion in the air to produce CO2 and H2O.
2) they’re soluble in water. their solutions have a neutral pH.
3) all alcohols can be oxidised by reacting with oxygen to produce a carboxylic acid.
why can alcohols such as methanol and ethanol used as solvents in industry?
because they can dissolve most things that water can dissolve, but they can also dissolve things that water cant. for example: hydrocarbons, oils and fats
why can the first 4 alcohols be used as fuels?
because they burn clearly and it doesnt smell bad
give the method and describe how ethanol can be made
-fermentation
1) using an enzyme in yeast to convert sugars into ethanol. CO2 is also produced and this reaction takes place in a solution, so the ethanol produced is aqueous.
2) its optimum temperature is around 37 degrees, in a slightly acidic solution and anaerobic conditions.
3) if the conditions were altered eg: high temp, the enzymes would denature
what is the word equation for fermentation?
sugar——>ethanol + carbon DIO
(yeast)
what is the formula for methanoic acid?
HCOOH
what is the formula for ethanoic acid?
CH3COOH
what is the formula for propanoic acid?
C2H5COOH
what is the formula for butanoic acid?
C3H7COOH
what is the general formula for a carboxylic acid?
Cn H2n+1 COOH
how do carboxylic acids react?
1a) they react (like any other acid) with carbonates to produce salt and water and carbon dioxide.
1b) the salts formed will end in
-anoate.
2) carboxylic acids dissolve in water and ionise and produce H+ ions.
2b) however they dont fully ionise, they just form weak acidic solutions. this means that they have high pH’s than aqueous solutions of strong acids.
what is the functional group of carboxylic acids?
COOH
what can be made from reacting an alcohol and carboxylic acid?
esters
what is the function group of an ester?
COO
what is the word equation for the formation of an ester?
alcohol + carboxylic acid——> ester + water
what is also usually used in the formation of an ester?
an acid catalyst eg: sulfuric acid
whats the name of the ester required by aqa?
ethyl ethanoate
what are polymers?
long molecules formed when lots of small molecules called monomers join together (polymerisation)
what are the conditions for polymerisation?
high pressure and catalyst
what are plastics made up of?
polymers that are usually plastic based and their monomers are usually alkenes
what are addition polymers made up of and what can they do?
unsaturated monomers (alkenes). a lot of them can open up their double bonds and join together to form polymer chains, this is called addition polymerisation
what are the products when monomers react in polymerisation, what is the product?
the ONLY product is the polymer, so the addition polymer has the same type and number of atoms as the monomers at the start
how can you draw a a displayed formula of a polymer from the displayed formula of its monomer?
1) start by drawing the two alkene carbons, replace the C=C with a C-C and add an extra single bond onto one of the carbons
2) then fill in the rest of the groups in the same way that they surrounded the double bond in the monomer
3) finally add a pair of brackets around the repeating bit and place an ‘n’ after it
how can polymers be made?
by addition polymerisation and condensation polymerisation
how can polymers be made by condensation polymerisation?
1) condensation polymerisation involves monomers which contain different functional groups.
2) the monomers react together and bonds form between them, making polymer chains.
3) the simplest types of condensation polymers contain 2 different types of monomer, each with 2 of the same functional groups
what do boxes in condensation polymerisation equations represent?
the carbon chain
what is the difference in the number of types of monomers between condensation polymerisation and addition polymerisation?
CP- 2 monomer types, rach containing 2 of the same functional group. or 1 monomer type with two different functional group
WHEREAS
AP- only 1 monomer type containing a C=C bond
what is the difference in the number of products formed between condensation polymerisation and addition polymerisation?
CP- two types of product. the polymer and a small molecule (eg water).
WHEREAS
AP- only one product formed. the polymer
what is the difference in the functional groups involved in polymerisation in condensation polymerisation and addition polymerisation?
CP- two reactive groups on each monomer
WHEREAS
AP- C=C bond in monomer
what are the 2 functional group that amino acids contain?
the basic amino group (NH3) and acidic carboxyl group (COOH)
what is the example of an amino acid and the structure that we have to know?
glycine
what can amino acids form and how can they do so?
they can form polypeptides via condensation polymerisation. an amino group of an amino acid can react with the acid group of another, and so on, to form a polymer chain. for every new bond, water is lost
what are one or long chains of polypeptides known as and what are their uses in the human body?
1) proteins
USES:
- enzymes work as catalysts
- haemoglobin works to transport oxygen
- antibodies form part of the immune system
- the majority of body tissue is made from proteins
1) what do polypeptides and proteins contain in their polymer chains?
2) what do the order of the amino acids do?
1) different amino acids
2) gives the proteins their different properties and shapes
what is DNA?
is found in every living thing and many viruses. it contains genetic instructions that allow the organism to develop and operate. its a large molecule that has a double helix structure
what is DNA made out of?
DNA is made of 2 polymer chains of monomers called ‘nucleotides’ and they each contain a small molecule known as a base.
what are the 4 bases in nucleotides known by?
A, C, G, T
what is the DNA structure?
the bases on the different nucleotide pair up with eachother and form cross links, keeping the 2 nucleotides together and giving the double helix structure.
- the order of the bases act as a code for an organisms genes
how can can simple sugars form polymers?
sugars can react together through polymerisation reactions to form larger polymers, eg starch, which living things use to store energy, and cellulose, which is found in plant cell walls
what are sugars?
small molecules that contain carbon, oxygen and hydrogen
what is the general formula for alkanes?
Cn H2n+2
