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Chemistry 1 Revision: C5 Alkenes, cracking, making ethanol and polymers
Task 1: Use the revision guide to produce a mini mind map or bullet point summary for the following key areas on this topic.
Task 2: Practise past questions and assess using the mark scheme
Cracking
Polymers
alkenes CnH2n bromine catalyst colourless
double heated shorter smaller unsaturated
cracking
vaporised
cooled deformed dental double ethene heated hydrogels
join monomers original packaging poly(ethene)
poly(propene) polymers propene small waterproof wound
Long chain hydrocarbons are broken down into smaller more useful
molecules by c……………………………..:
In polymerisation the d………….… bonds in many s………………… molecules
1. long chain fraction is h…………………… and v……………………………….
– called m………………….……. – open up so that the monomers can j………….
2. vapours pass over a c………………………
together to form very large molecules called p……….……….….. e.g.
3. products have s……………….. chains / are s…………………. molecules
containing fewer carbon atoms
4. products of cracking are a mixture of a…………………… and alkanes
n
→
n
Alkenes
General formula ………………………
U………………………………………. hydrocarbons – have a d…………………
carbon-carbon bond
e....…………….
p……………………………………………
Complete the diagram below to show how the monomer forms a
polymer. What are the names of the monomer and the polymer?
Alkenes react with b……………… water, turning it from
orange to c……………………..
Ethanol
carbon dioxide carbon neutral energy ethene fast few
food habitat high impure land labour locked up low
many non-renewable not oil other plants pure
renewable slow sugar temperature waste water
Hydration of ethene (from
o…..…….)
Fermentation of sugar (from
p……………..)
e……………… + w…………..…. → ethanol
s……….… → ethanol + c………….. d……….…..
disadvantages
advantages
• n...………………………….. resource
• r………………..…………….. resource
• higher t………………………………..
needed for process so uses
• lower t………………………………………..
needed for process – so uses
more e ……………………
less e………………………
• h………. safety risk
• n………….. carbon neutral –
releases l………… u…… carbon
• risk of major o…….. spillage
• ethene could be used to
make o……………… products
advantages
• continuous process – f………..
• f……….. steps in the process
• ethanol is p………….
• ‘conserves’ f…………….
break down
p…….………………………………………….
Polymers have many uses e.g. p……………………….., w……………………………………
coatings for fabrics, d…………………… polymers, w………………… dressings,
and h……………………………. Shape memory polymers can be d…………………….
but return to their o………………………… shape when heated or cooled.
Disposal of polymers
biodegradeable carbon collected crude oil electricity
energy expensive explosions fewer fuel heating
landfill methane products split times toxic waste
Advantages
Re-use
 saves raw materials/c………… o……
Disadvantages
• l…………. safety risk
 saves e……………….
 bags easily s……………
• c………………. n………….…………. carbon dioxide used by plants in
photosynthesis
 f………………… bags needed
 reduces c…………… /CO2 emissions
• can use w…………….. plant
material
disadvantages
 saves cost of new bags
• batch process – s………….
• m………….. steps in the process
 saves e………………….
• ethanol is i…………………
 reduces c………….. /CO2 emissions
• potential f……………. shortages
 reduces use of l………………..
• needs large areas of l…………. to
grow crops and particular
climates
• potential h………………… loss
• crops grow slowly
 can be used for new p…………………
Burned
• l……………………. intensive process
e………………………………….
microbes
polymers soil waste
Many p………………………. are not b……………………………….., so they are not
broken down by m…………………………… in the s…………... This can lead to
problems with w…………………….. disposal.
Biodegradable plastics made from corn starch have been developed;
these b………………….. d…………………. more easily.
 unable to reuse many t…….
 reduces use of l…………………
 no w…………….
Recycled
 saves raw materials/c………… o…..
Biodegradeable polymers
biodegradeable
p………………………
 e…………….. released can be
used for h……………….. / generating
 reduces use of l……………………….
Dumped
 can be c……………….. / transported
with household w…………………………
 some plastics are
b……………………….... - slow breakdown
produces m……………………. which can
be used as a f…………….
 non-b………………………………. plastics
will not release CO2 / into the air
 has to be c…………………… /
transported / washed /
separated / melted – can
be e……………………….
 has to be c………………………….
/ transported
 w……………….. of resources
 releases t……… gases /CO2
 w………………….. of resources
 plastic uses l………………………
 produces m……………………….
which is a greenhouse gas /
could cause e…………………………
 not b…………………………………….