module seven - revision deck Flashcards
alkane general formula
CnH2n+2
characteristics of alkanes, alkenes and alkynes
saturated hydrocarbons
non-polar
dispersion forces
generally low boiling points, increase as carbon chain increases
alkene general formula
CnH2n
Alkyne general formula
CnH2n-2
alcohol general formula
CnH2n+1OH
primary alcohol
one in which only one carbon atom is bonded to the carbon atom attached to the OH group
carbonyl function group
oxygen double bonded to a carbon
aldehyde
carbonyl group attached to a terminal carbon atom of the chain
suffix -anal
ketone
carbonyl group attached to a middle carbon
suffix - anone
carboxyl group
carbon double bonded to an oxygen and a hydroxyl group
amine general formula
R-NH2
amines
contained NH2 attached to a hydrocarbon chain
can be classified as either primary, secondary or tertiary depending on how many hydrocarbon groups are attached to the nitrogen
amide
contains a carbon double bonded to an oxygen as well as an NH2 group
formed from carboxylic acids when the hydroxyl group is replaced by an amine group
amide general formula
RCONH2
isomer
molecules that have the same molecular formula but their atoms are arranged differently
chain isomers
involve rearrangement of the carbon skeleton
position isomers
made by moving the position of the functional group
functional group isomers
compounds with the same molecular formula but a different functional group
intramolecular bonds in alkanes, alkenes, alkynes
strong covalent bonds
shape of single bonded carbon molecules
tetrahedral with a bond angle of 109.5 degrees
shape of carbon carbon double bond
trigonal planar with bond angle of 120 degrees
shape of carbon carbon triple bond
linear with a bond angle of 180 degrees
environmental impact of hydrogens
mining for crude oil and natural gas is often ocean-based
oil spills can cause severe environmental damage
burning fossil fuels releases carbon dioxide, a greenhouse gas
production and transport of fossil fuels causes methane emissions
Exxon Valdez Oil Spill
1989 Exxon Valdez oil spill in alaska saw 41 million litres of oil spilled, contaminating > 1800km of coast lines, causing four human deaths and hundreds of thousands of animal deaths
greenhouse gas definition
cause heat to be trapped in the earth’s atmosphere causing global warming
economic impact of hydrocarbons
reliable energy source for industries
global economy is reliant on effective and reliable transportation which is primarily fuelled by hydrocarbons
leads to job creation
sociocultural impacts of using hydrocarbons
polymers are used in packaging, clothing, homewares, varnishes and adhesives
can be used to create medicines and pharmaceutical drugs
reliable and quick source of energy to power our lives
relatively inexpensive and accessible source of energy
addition reactions
unsaturated molecules undergo addition reactions where two or more molecules are joined to form a larger molecule
halogenation
alkene + halogen –> dihaloalkane
hydrogenation
alkene + hydrogen –> alkane
usually occurs in the presence of a metal catalyst such as nickel, platinum, palladium or rhodium
hydration
alkene + water –> alcohol
requires a dilute sulfuric acid catalyst
hydrogen halide addition
alkene + hydrogen halide –> haloalkane
Markovnikov’s rule
when a compound of the form HX is added to an asymmetrical alkene, the hydrogen becomes attached to the carbon with more hydrogens already attached to it
substitution reactions
occur in saturated molecules where one species on a molecule is replaced by another
alkane substitution with halogens
alkane + halogen –> haloalkane + hydrogen halide
the halogen molecule is broken up in the presence of UV light, creating a free radical
the free radical replaces one of the hydrogens on the alkane creating a haloalkane and a hydrogen halide
properties of alcohols
polar molecule due to hydroxyl group
higher boiling points than respective alkanes
increased branching lowers the boiling point due to weaker dispersion forces
small alcohols are more soluble in water
flammable
enthalpy of combustion of alcohols
enthalpy of combustion refers to the change in the total energy of a system during a combustion reaction
combustion of alcohols
alcohols burn in oxygen, forming water and carbon dioxide
dehydration of alcohols
alcohol –> alkene + water
requires a concentrated acid or aluminium oxide catalyst as well as heat
substitution with HX
alcohol + hydrogen halide –> alkyl halide + water
in reactions with hydrogen halides, tertiary are most reactive
oxidation of alcohols
requires an oxidising agent as potassium permanganate or acidified potassium
primary alcohol –> aldehydes –> carboxylic acids
secondary alcohol –> ketones
tertiary alcohols do not undergo oxidation
production of alcohols from alkenes
alkene + water in the presence of sulfuric acid –> alcohol
production of alcohol from halogenated organic compounds
haloalkane + water –> alcohol + hydrogen halide
production of alcohol from fermentation
C6H12O6 –> 2C2H5OH + 2CO2
temperature must be kept low, slightly acidic pH, anaerobic conditions, yeast catalyst
formation of fossil fuels
form from the remains of ancient plants, animals and microorganisms and are a non-renewable resource
coal forms when wood degrades over a long period of time. Black coal has the highest carbon percentage, so it releases the most heat. Coal is used to generate 75% of electricity in Australia
crude oil is a mixture of hydrocarbons consisting mostly of alkanes of different lengths. It’s separated into its constituents using fractional distillation
natural gas is mostly made up of methane
biofuels
derived from plant material like sugar cane, vegetable oils and grains
biogas
biogas is a mixture of gases that are released during the anaerobic breakdown of organic waste such as sewage, agricultural waste, rubbish and food waste
bioethanol
bioethanol can be formed through the fermentation of starch
bioethanol is blended with regular petrol to make e10
biodiesel
biodiesel is a fuel containing a mixture of esters. These esters are derived from vegetable oils or animal fats like palm oil, canola oil and lard through the process of transesterification
energy release - natural gas vs. bioethanol
natural gas releases 54kJ/g while bioethanol releases only 30kJ/g
properties of alcohols - boiling point
boiling point increases as the molecule size increases and are a lot higher than the parent alcohol. this is due to the presence of dipole-dipole forces and hydrogen bonds
increased branching reduces the strength of dispersion forces so long alcohols have higher boiling points than branched alcohols.
the more crowded the hydroxyl group, the harder it is to form hydrogen bonds, so boiling point decreases from primary to tertiary
properties of alcohols - solubility
small alcohols dissolve easily in water because the new hydrogen bonds formed with water have a similar strength to the exisiting hydrogen bonds between alcohols molecules
in larger alcohols, the hydrocarbon chain can only form dispersion forces with the water molecules, which aren’t as strong as the existing hydrogen bonds
properties of aldehydes and ketones
carbonyl group is highly polar resulting in the formation of dipole-dipole bonds. this results in higher boiling points than alkanes/alkenes but lower boiling points than alcohols
more soluble in water than hydrocarbons but less soluble than alcohols
formation of amines
hydrogens from ammonia are replaced with an alkyl group
primary, secondary and tertiary amines
primary amines are when one hydrogen from the ammonia is replaced with an alkyl group
secondary amines form when two hydrogens from the ammonia molecule are replaced with alkyl groups
tertiary amines are when all three hydrogens are replaced with alkyl groups
properties of amines
polar molecules with high boiling points due to hydrogen bonds - lower boiling points than alcohols as nitrogen is less electronegative than oxygen
amides properties + test
polar molecules with high boiling points due to hydrogen bonds
to test for an amide: add sodium hydroxide solution and heat. if it gives off ammonia when heated, but not when cold, it is an amide.
ammonia is characterised by its odour and it turns red litmus paper blue
carboxylic acid properties
weak acids
more polar than alcohols and have high boiling points due to the presence of hydrogen bonds
shorter chains are soluble in water, but solubility decreases as length of carbon chain increases
comparing boiling point of organic compounds
alkanes, alkenes, alkynes - esters - amines - alcohols - carboxylic acids - amides
alkanes and alkenes have relatively low boiling points since they have only dispersion forces
haloalkanes have much higher boiling points due to their polarity
the more electronegative atoms in a molecule, the more hydrogen bonds can form and therefore the higher boiling point
aldehydes and ketones can’t form hydrogen bonds so they have lower boiling points
carboxylic acids have higher boiling points than alcohols
amides have the highest boiling point as they contain both oxygen and nitrogen
amines generally have lower boiling points than organic compounds with oxygen
comparing solubility of organic compounds
non-polar hydrocarbons are insoluble in water
small polar molecules can form hydrogen bonds with water molecules making them soluble - solubility decreases as the molecule gets larger
in organic solvents, hydrocarbons and haloalkanes are soluble
solubility of polar organic molecules in organic solvents increases as they become larger
branching reduces the boiling point and solubility of organic compounds in water
formation and structure of esters
formed by combining an alcohol with a carboxylic acid
similar structure to carboxylic acids, except that an alkyl group is attached to the oxygen rather than a hydrogen atom
concentrated sulfuric acid is used as a catalyst and it is also heated to speed up the reaction
reflux is used
properties of esters
tend to be liquid at room temperature
boiling points are much lower than carboxylic acids of similar masses as their main forces are dipole-dipole
most are not very soluble in water, but are in organic molecules
reflux process
reactants are heated for an extended period of time without any loss of reactants or products
as the mixture is heated, the volatile components evaporate and move into a vertical condenser where the gases are cooled so they return to the reaction mixture in the flask
organic components of reflux mixture
ester
carboxylic acid
alcohol
inorganic components of a reflux mixture
water sulfuric acid (present in ion form)
substitution reaction to form amines
haloalkane + ammonia –> amine + ammonium salt
condensation reaction to produce primary amides
carboxylic acid + ammonia –> primary amide + water
condensation reaction to produce secondary amides
carboxylic acid + primary amine –> secondary amine + water
LDPE production
produced using high temperatures ad pressure
LDPE structure
significant branching and is an amorphous polymer
LDPE properties and uses
low density, lower melting point, lightweight and flexible
used to make plastic bags, soft toys and plastic food wrap
HDPE production
produced using lower pressures and temperatures and a Ziegler-Natta Catalyst
HDPE structure
unbranched, crystalline polymer. this structure allows it to form stronger dispersion forces
HDPE properties and uses
higher melting point and less flexibility
used for plastic water bottles, shampoo bottles and recycling bins
hdpe is more opaque, rigid and has higher tensile strength compared to ldpe
polyethylene monomer
(CH2CH2)n
vinyl chloride monomer (chloroethene)
(CH2CHCl)n
PVC structure
mainly amorphous because of the way the chlorine atoms stick out from the chain and their size
dipole-dipole forces due to the highly electronegative chloride
PVC properties and uses
tends to be hard and rigid and is one of the most widely used polymers
high melting point
plasticisers are sometimes added to make the polymer softer and more flexible
used for electrical insulation, garden hoses and drainage and sewerage pipes
styrene monomer
(CH2CHC6H5)n
polystyrene structure
mainly amorphous because of the way the phenyl ring sticks out from change
no polar bonds due to the symmetry of the phenyl ring so only weak dispersion forces
polystyrene properties and uses
tends to be clear, hard and brittle, however it is readily softened and moulded on heating and becomes rigid when cooled
used to make car battery cases, disposable drink cups and foam packaging materials
tetrafluoroethylene monomer
(CF2CF2)n
formation of PTFE
manufacturing process involves the synthesis of chloroform, fluorospar and sulfuric acid. some steps require temperatures of around 700 degrees
PTFE properties and uses
commonly known as teflon - the non-stick surface on pans
also used to treat carpets and fabrics to make them stain resistant
very strong and is used to make high grade electrical insulation and pipe thread sealant
properties are due to the polar carbon-fluorine bonds and dipole-dipole interactions between the polymer chains
Nylon -6,6
formed from hexandioic acid and 1,6-hexanediamine
(COC4H8CONHC6H12NH)n
nylon-6,6 properties and uses
hydrogen bonds
strong fibres with high tensile strength
used to make clothing and fabrics, ropes and fishing lines and even machinery parts
properties are determined by the length of the monomer’s carbon chain. as chain length increases, absorbency and melting point decrease due to less hydrogen bonding
Polyethene Terephthalate
PTE is formed from monomers 1,4- benzenedioic acid and 1,2 - ethanediol
Polyethene Terephthalate properties and uses
polar ester group forms strong dipole-dipole forces between chains, making it a strong polymer
used to make clothing and fabric as well as recycable plastic bottles and packaging
