1) crude oil is vapourised , 2) the compounds evaporated
and the vapourised crude oil enters the fractioning tower, 3)
the smaller the molecules, the lower their boiling point-->
the higher they rise in the tower before condensing and
being collected as fractions [compounds with the lowest
boiling points are obtained at the top of the tower
produces more long-chain hydrocarbons (supply
greater than demand and less useful) that can be used
directly and fewer short- chain hydrocarbons
(demand greater than supply, more useful) than
required therefore cracking necessary(produces a
mixture of alkanes and alkenes of varying lengths
cracking process: (thermal decomposition): 1)
catalyst mixture of silica [silicon dioxide] and
alumina [aluminium oxide]--> porous pot, 2)
600 degrees
the mixture of compounds in crude oil is
separated because the compounds have
different numbers of carbon atoms and
therefore have different boiling points and
so condense at different temperatures in
the tower
as you go up the tower the boiling point decreases, the
lower the boiling point, the paler in colour, less viscous the
liquid, more volatile, more flammable, the clearer the flame
on combustion
Refinery gases (fuel), Gasoline (petrol), Kerosene
(fuel in jet engines), Diesel (fuel in diesel engines),
fuel oil (fuel in ships), Residue/ Bitumen (used to
make bitumen for surfacing roads
incomplete combustion: may produce carbon
monoxide which is poisonous because it reduces the
capacity of the blood to carry oxygen
car engines: temperature reached is high enough to allow nitrogen
and oxygen from air to react, forming nitrogen oxides and sulfur
dioxides which are pollutant gases that contribute to acid rain
Problems of acid rain: corrosion of buildings and
metal statues, acidifies lakes: kills equatic animals
ALKENES
gen
unsaturated, double bonds
addition of halogens: one
product
Hydrogenation ( addition og hydrogen)
conditions
150 degrees, nickel catalyst
margarine manufacture, liquid oils
into solid facts
TEST FOR UNSATURATED (ALKENES)/ SATURATED (ALKENES) COMPOUNDS
1) addition of bromine water, 2) orange/ brown bromine
water is decolourised in alkenes, 3) orange/ brown
bromine water would remain its colour in alkanes
ALKANES
saturated, only single bonds
the greater the chain length, the greater the
attractions between the molecules (intermolecular
forces)--> more difficult it is to overcome therefore the
boiling point increases furthermore more energy is
requires
combustion
complete: carbon dioxide and water produced
incomplete: carbon monoxide and water
produced OR carbon and water produced
Substitution reaction: two products
alkanes react with halogens in the
prescence of UV light
ETHANOL
alcohols form a homologous series with the functional group -OH
manufacture of ethanol
passing ethene and steam over a
phospheric acid catalyst at a temparature
of 300 degrees and pressure of 60-70
atmosphere
finite resources (crude oil), continuous flow (more
efficient), rapid, produces purer ethanol, high temp. and
pressure (high energy input)
fermentation of sugars at a temperature of 30 degrees, zymase, sugar sauce, anerobic
renewable (sugar cane), batch process (inefficient), slow,
produces impure ethanol, general temperature and normal
pressure
drinks, fuel and slovents
dehydration of ethanol produces ethene (hot
catalyst--> aluminium oxide)
SYNTHETIC POLYMER
an addition polymer is formed by joining up many small
molecules called monomers they are also hard to dispose
of as their inertness means that they do not easily
biodegrade
uses of polychloroethane (guttering and electrical
insulation), uses of polyethene (packaging, electrical
insulator, plastic bowl, buckets), uses of polypropene
(packaging and ropes)
problems with polyalkenes: non- biodegradability and
problems of disposal as HCN and HCl can be formed
from some polymers, solutions: recycling and
production of biodegradable polymers
some polymers (e.g. nylon) form by condensation
polymerisation--> produces a small molecule e.g.
water or hydrogen chloride as well as the polymer