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state what hydrocarbons are
compounds that contain
ONLY
carbon and hydrogen atoms
explain what crude oil is
a complex mixture of hydrocarbons
containing molecules
in which carbon atoms are in chains or rings
an important source of useful substances
a finite resource
describe and explain how crude oil is separated into more useful mixtures by fractional distillation
fractional distillation is carried out in a fractionating column which is very hot at the bottom and very cool at the top
crude oil enters the fractionating column and is heated, so the crude oil vapour rises
vapours of hydrocarbons with very high boiling points will cool and condense and be collected at the bottom of the column
vapours of hydrocarbons with very low boiling points will cool and condense and be collected at the top of the column
different fractions condense at different heights based on their boiling point
fractions containing smaller hydrocarbons will be collected as gases in higher sections of the column
fractions containing larger hydrocarbons will be collected in lower sections of the column
state the uses of natural gases
domestic heating
cooking
state the use of petrol
fuel for cars
state the use of kerosene
fuel for aircrafts
state the uses of diesel oil
fuel for some cards
fuel for trains
state the uses of fuel oil
fuel for large ships
fuel for power stations
state the uses of bitumen
used to surface roads
used to surface roofs
explain how hydrocarbons in different fractions within crude oil differ from each other by the number of carbon and hydrogen atoms they contain
fractions with longer hydrocarbons will have more hydrogen and carbon atoms
fractions with shorter hydrocarbons will have less hydrogen and carbons
as the length of the chain relies on the amount of carbon atoms in the molecules
explain how hydrocarbons in different fractions within crude oil differ from each other by boiling points
fractions with longer hydrocarbons will have higher boiling points
fractions with shorter hydrocarbons will have lower boiling points
as it takes more energy to overcome more covalent bonds between carbon and hydrogen atoms
explain how hydrocarbons in different fractions within crude oil differ from each other by ease of ignition
fractions with longer hydrocarbons will be harder to ignite
fractions with shorter hydrocarbons will be easier to ignite
as it takes more energy to overcome more covalent bonds between carbon and hydrogen atoms
explain how hydrocarbons in different fractions within crude oil differ from each other by viscosity
fractions with longer hydrocarbons will be more viscous
fractions with shorter hydrocarbons will be less viscous
as the intermolecular forces of attraction in longer hydrocarbon chains are stronger
and there is a higher chance of longer chains entangling
state what the different hydrocarbon fractions within crude oil have in common
they are mostly members of the alkane homologous series
explain what a homologous series is
a series of compounds
which have the same general formula
differ by CH2 in molecular formulae from neighbouring compounds
show a gradual variation in physical properties
and have similar chemical properties
describe what the complete combustion of a hydrocarbon is
an exothermic reaction
where carbon dioxide and water are produced
and energy is given out
state what the incomplete combustion of hydrocarbons produces
carbon/soot
carbon monoxide
explain why the incomplete combustion of hydrocarbons produces carbon and carbon monoxide
an incomplete combustion occurs due to a lack of enough oxygen
carbon and carbon monoxide are produced as there is not enough oxygen to produce carbon dioxide and water
explain how carbon monoxide behaves as a toxic gas
carbon monoxide causes loss of consciousness and suffocation
as once breathed in, it binds to haemoglobin in the blood
meaning oxygen cannot bind to the haemoglobin
restricting the amount of oxygen carried around the body to organs
causing suffocation
explain the problems of incomplete combustion in appliances that use carbon compounds as fuel
when incomplete combustion occurs, carbon and carbon monoxide are created
these can be used as fuel by the appliance
and cause an electrical fire
explain how impurities in some hydrocarbon fuels results in the production of sulfur dioxide
hydrocarbon fuels are often contaminated with small amounts of sulfur impurities
when these fuels are combusted, the sulfur in the fuels gets oxidised
which forms sulfur dioxide
explain some problems associated with acid rain caused when sulfur dioxide dissolves in rain water
acid rain can cause corrosion to metal structures, buildings and statues made of carbonate rocks
acid rain can damage aquatic organisms
acid rain can pollute crops and water supplies
acid rain can irritate lungs, throats and eyes
explain why, when fuels are burned in engines, oxygen and nitrogen can react at high temperatures to produce nitrogen oxides
nitrogen oxides are produced when nitrogen and oxygen react at high temperature and pressures inside internal combustion engines
nitrogen oxides are pollutants
state the advantages of using hydrogen instead of petrol as a fuel in cars
it releases more energy per kilogram than any other fuel
it does not pollute as it only produces water during combustion
state the disadvantages of using hydrogen instead of petrol as a fuel in cars
its expensive to produce and requires energy for the production process
its difficult and dangerous to store and move around
the production of hydrogen releases carbon dioxide
state what type of fuel petrol, kerosene and diesel oil are
non-renewable fossil fuels
obtained from crude oils
state what type of fuel methane is
non-renewable fossil fuel
obtained from natural gases
state what cracking is
the breaking down of larger, saturated hydrocarbons (alkanes)
into smaller, more useful saturated hydrocarbons
and some unsaturated hydrocarbons (alkenes)
explain why cracking is necessary
some shorter chain hydrocarbons are in higher demand
than long chain hydrocarbons
cracking allows the long chain hydrocarbons to be broken down into shorter chain hydrocarbons
therefore not wasting long chain hydrocarbons
and increasing the supply of shorter chain hydrocarbons
which are more reactive, less flammable and less viscous
state what is produced by volcanic activity in earth’s early atmosphere
gases
state what earth’s early atmosphere was thought to contain
little or no oxygen
a large amount of carbon dioxide
water vapour
small amounts of other gases
explain how condensation of water vapour formed oceans
as volcanic activity decreased, global temperature decreased
this cooling of temperature caused the condensation of water vapour into liquid water
this liquid water formed the oceans
explain how the amount of carbon dioxide in the atmosphere was decreased when carbon dioxide dissolved as the oceans formed
carbon dioxide is water soluble
when water vapour in earth’s early atmosphere condensed, carbon dioxide dissolved in the oceans
carbonates were precipitated during this process, later forming sediments on the seabed
explain how the growth of primitive plants gradually increases the amount of oxygen in earth’s early atmosphere
plants use photosynthesis to create energy in glucose form
carbon dioxide is a reactant in photosynthesis
oxygen is a product of photosynthesis
as plants continued to grow, the amount of oxygen in the atmosphere increased
and the amount of carbon dioxide in the atmosphere decreased
describe the chemical test for oxygen
place a glowing splint in a test tube containing the unknown gas
if the splint relights, oxygen is present
explain what the greenhouse effect is
when carbon dioxide, methane and water vapour in earth’s atmosphere
absorb heat radiated from the earth
and subsequently release energy which keeps earth warm
evaluate the evidence for human activity causing climate change, considering the correlation between the change in atmospheric carbon dioxide concentration, the consumption of fossil fuels and temperature change
fossil fuels are the most used energy source globally
when fossil fuels are combusted, they produce the greenhouse gases: carbon dioxide, methane and nitrous oxide
these gases enhance the greenhouse effect, allowing for a global temperature increase
and climate change
evaluate the evidence for human activity causing climate change, considering the locations where the greenhouse gas measurements are taken and historical accuracy
historical data is much less accurate due to the lack of accurate instrumentation and methods
fewer locations would have been measured due to lack of satellites and transport
state the composition of earth’s modern atmosphere
78% nitrogen
21% oxygen
1% argon
~1% carbon dioxide
~1% neon
~1% methane
explain the potential effects of increased levels of carbon dioxide and methane on the climate
carbon dioxide and methane are greenhouse gases
so once they’re in the atmosphere, they enhance the greenhouse effect
this increases the heating effect on the earth
increasing global temperature
and increasing the chances and effects of climate change occurring
state the main way carbon dioxide is released into the atmosphere
the combustion of fossil fuels
as carbon dioxide is a product of the complete combustion of hydrocarbons within the fossil fuels
state the main way methane is released into the atmosphere
livestock farming
as during the digestive processes, farm animals produce methane
which is then released into the environment
explain how the amount of carbon dioxide released into the atmosphere can be decreased
changing from using fossil fuels as an energy source to renewable energy sources such as solar or wind
as this will decrease the demand for fossil fuels
decreasing the amount of fossil fuels being combusted
decreasing the carbon dioxide being released into the atmosphere
explain how the effects of carbon dioxide in the atmosphere can be mitigated
planting more plants and trees
as they will use up carbon dioxide during the photosynthesis reaction
and produce oxygen as a product
explain how the amount of methane released into the atmosphere can be decreased
people adopting a vegetarian or vegan diet
as this will decrease the demand for livestock
therefore decreasing the amount of livestock being farmed
decreasing the amount of methane being produced
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