Studied by 2 people
what is a hydrocarbon
a compound made up of only hydrogen and carbon
alkanes are a homologous series what does this mean?
has the same functional group and with the similar chemical properties
what is determines by the functional group of organic molecule?
the properties and reactions of the molecules
an organic compound has the formula CH3CHO, identify its functional group
aldehyde
what is a stereoisomer?
compounds that have the same structural formula but a different arrangement in space
what causes E/Z isomerism to occur
this is because there is a lack of rotation around the double bond
what is the difference between cis-trans isomerism and E/Z isomerism
cis/trans isomers requires two different groups attached at the end of the C=C bond must have two groups however the two ends of the C=C must have one group in common with each other (usually hydrogen). E/Z is more general there can be four different groups attached to the double bond or the same group may appear on each side
what takes place in an addition reaction
small molecules is added to the alkene causing the double bond to break and a saturated compound to be produced as the product
alkenes generally undergo what type of reaction
electrophilic addition
a functional group is replaced by a different group, what is this type of mechanism
substitution
small molecule is remove from a compound and leaves behind an alkene what type of reaction is this
elimination
describe the processes used in isolating useful alkanes from crude oil
Fractional distillation - the heat increases as you go up the column all the alkanes have a different boiling point so when it rises up the column they will condense at different point.
cracking - thermal or catalytic cracking - shortens alkanes and alkene chains.
reforming - straight chains converted into branched alkanes and cyclic alkanes for combusting
what pollutants can be formed during combustion of alkane fuels
Caron monoxide, nitrous oxide, sulfur oxide, unburnt hydrocarbons, carbon particles
what are the problems associated with nitrous oxide and sulfurous oxide
forms acid in the atmosphere and the emissions contribute to acid rain which can lead to erosion.
what process is carried out by catalytic converters
it turns nitrous oxide, Carbon monoxide and unburnt hydrocarbons into nitrogen gas, carbon dioxide and water.
why are biofuels such as biodiesel and bioalcohols considered to be carbon neutral
they are made from plant matter, the carbon plant matter s converted from carbon dioxide. only as much carbon dioxide is produced as was used to grow the plants so there is no net gain in carbon dioxide.
what are tow advantages and disadvantages of biofuel compared to natural gas
advantages - carbon neutral, renewable, low cost compared to drill oil
disadvantages - low production, uses land which could be used for crops.
what is homolytic fission
the splitting of a covalent bond where each atom receives one electron from the bond, creating radicals
why is free radical substitution difficult to control
radicals are highly reactive, and it is not possible to control what species react resulting in multiple substitutions of halogens as well as the creations of longer chain alkanes that may not be a desired product of the reaction - these products may react further
why are free radical substitution reaction often not suitable for synthesis of organic molecules
products of radical substitution are reactions of mixtures of multiple molecules so further reactions will produce mixture of products.
why can alkenes be attacked by electrophiles
C=C double bond in the structure of alkenes is a region of high electron density and electrophile get attracted
what are the reagents and conditions required to convert an alkene into an alcohol
steam and an acid catalyst
what reagents are used to convert an alkene into a diol
acidified potassium manganate and water
what is produced in heterolytic fission
ions of opposite charge
what is a polymer
large molecule made up of many repeat units or monomers
one benefit of recycling polymers
reduce waste going to landfill, combustion of waste polymers produces energy
give two ways other than recycling that polymer waste can be utilised
incineration for energy, use as a feed stock for making smaller alkanes and alkenes by cracking
limitation of recycling polymers
recycling is expensive, toxic waste products have to be removed, not all plastics can be recycled, polymers must be sorted
ways to reduce the environmental impact of polymer disposal
creating biodegradable polymers, remove toxic products when polymers are being combusted for energy
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