C16-17 FUELS AND ATOMOSPHERE Flashcards
Hydrocarbon
a compound containing hydrogen and carbon only
crude oil
a thick brown liquid made of a mixture of many different hydrocarbons found in deposits underground
molecules in crude oil
hydrocarbons in many different forms with carbons joined together into both chain - and ring - shaped molecules
properties of hydrocarbons in crude oil
most of the hydrocarbons in crude oil are liquids , but each of them has a different boiling point
hydrocarbons in crude oil
mostly alkanes
uses of crude oil
fuel , feedstock , for the chemical industry
crude oil as a finite resources
there is a limited amount : at some point it will run out
non-renewable
a resource that will eventually run out
fractional distaltion
a type of distillation used to separate mixtures of two or more liquids
separation in fractional distillation
fractional distillation separate compounds according to their boiling point
heating crude oil
crude oil is passed through a heater to heat it to about 400oC so that nearly everything is a gas
separating crude oil in a fractionalising column
the hot gases rise up the fractionalising column until cool enough to condense
fractions of crude oil
the separated liquids and gases collected at different temperatures . the main ones are gases, petrol, kerosene, diesel oil, fuel oil and bitumen
fraction in order
gases, petrol, kerosene, diesel, fuel , bitumen smallest to baddest molecule lowest to highest boiling point lowest to highest viscosity easiest to hardest ignition
viscosity
how easily a fluid flows =- higher viscosity = runnier
ease of ignition
how easily a substance catches fire
gases
used for domestic heating and cooking
petrol
used as a fuel for cars
kerosene
fuel for aircraft
diesel oil
fuel for larger vehicles such as lorries and trains
fuel oil
fuel for ships and power stations
bitumen
surfacing roads and roofs
homologous series
a family of closely related compounds with molecular formulae that differ only in the number of H2’s
physical properties in a homologous series
vary gradually, for example the boiling point gradually increases
chemical properties in a homologous series
very similar with a gradual variation
general formula
describes the number of each atom in any member of a homologous series
alkanes
hydrocarbons containing only single bonds. the names end with ane
first three alkanes
methane CH4
ethane C2H6
propane C3H8
general formula of alkanes
CnH2n+2
combustion
when a compound reacts with oxygen producing a flame
complete combustion
combustion that produces only water and carbon dioxide and releases the most possible energy
complete combustion equation
fuel + oxygen - carbon dioxide + water
incomplete combustion
combustion that produces a mixture of carbon dioxide , carbon monoxide, carbon and water and produces less energy
why incomplete combustion happens
where there is not enough oxygen for all of the reactants to be fully oxidised
carbon monoxide
CO. A colourless odourless a highly toxic gas
how carbon monoxide kills
it sticks to haemoglobin in he blood which prevents it from carrying oxygen
soot
the small particles of carbon produced by incomplete combustion
problems with soot
causes lung problems when breathed in
blackens and dirties buildings
preventing incomplete combustion
it is important that boilers at home have a good air supply to prevent incomplete combustion. for this reason a boilers flue pipe should be checked for blockages every year
sulfur
an impurity that is naturally present in small amounts in oil an coal
sulfur dioxide
S02 A gas formed from the sulphur in oil and coal when it is burnt
acid rain
rain with a pH lower Han 5.2
formation of acid rain
sulfur dioxide dissolves in water in clouds to form sulphurous acid H2SO3 which oxidises to become sulphuric acid H2SO4
nitrogen oxidises
NOx various gases formed at high temperatures inside internal combustion engines
problems of nitrogen oxides
can dissolve in clouds to form acid rain
no2 causes lung damage
noX can cause smog to form
cracking
breaking down longer less useful hydrocarbons into shorter more useful ones
how to crack hydrocarbons
heat the hydrocarbons and pass the vapours over an aluminium oxide catalyst heated to 650
products of cracking an alkane
an alkane and an alkene
C6H14 - C4H10+C2H4
alkene
A hydrocarbon containing a C=C double bond
usefulness of cracking
there is more demand for shorter hydrocarbons - such as petrol and gas - than longer ones such as bitumen . cracking turns the less useful ones into more useful one
hydrogen gas as a fuel
H2 hydrogen has the potential to be used as a fuel for cars
advantages of hydrogen as a fuel
it only produces H2O when burnt so does not directly contribute to global warming
it can be produced using renewable energy
disadvantages of hydrogen as a fuel
most of its currently produced in ways that also produced in ways that also produce CO2 which contributes to global warming
it is difficult to store
the early earth
4.5-3.5 billion years ago the earth was extremely hot and there were many volcanoes
the early atmosphere
little or no oxygen a lot of carbon dioxide , water vapour , small amounts of other gases such as nitrogen
origin of the early atmosphere
gases from volcanoes
evidence for a lack of oxygen
the oldest rocks on earth contain compounds such as iron pyrite that cannot form in the presence of oxygen
formation of the oceans
as the earth cooled, water vapour in the air condensed to liquid water, forming the oceans
changes to the atomsphere
the amount of carbon dioxide decreased , water vapour decreased , oxygen increased
photosynthesis and the atmosphere
photosynthesis - by - cyanobacteria and plants - consumes carbon dioxide (decreasing it)and produces oxygen (increasing it)
oceans and carbon dioxide
carbon dioxide dissolves in the ocean and is used by sea creatures to make their shells, enabling even more CO2 to dissolve
test for oxygen
a glowing slant (stick) placed in oxygen will relight
greenhouse effect
infrared radiation (heat0 from the sun travels though the atmosphere and warms the ground the ground re-emits slightly different infrared radiation that is not able to pass back through the atmosphere and is trapped by gases called greenhouse gases
greenhouse gases
gases that trap re-emitted infrared radiation - including carbon dioxide , methane and water vapour
importance of the greenhouse effect
the greenhouse effect is extremely important : without it the average global temperature would be 32oC lower and most life could not exist
increased greenhouse effect
human activities are increasing the concentration of greenhouse gases such as carbon dioxide and methane , meaning the greenhouse effect is strong and traps more heat
global warming
an increased in global temperatures caused by the increased greenhouse effect
climate change
change in global weather patterns caused by global warming
correlation between carbon dioxide and temperature
in earths history , every time CO2 concentrations have been high , the temperature has also been high
this makes scientists think that the current increase in CO2 is what is increasing the temperature
uncertainty in the data
scientists measurements of past temperature and co2 are not perfect which makes some people doubt them. however, many different sets of data say similar things, so most scientists believe them
two man causes of climate change
carbon dioxide produced by burning fossil fuels
methane produced by farming
effects of climate change
rising average global temperature
increased sea levels from melting ice
increased drought in some areas and flooding in others
increase in dangerous weather
effect of climate change on life
living organisms are adapted to the conditions where they live. if these conditions change they may struggle to survive. climate change is causing many species to struggle and some to go extinct
ocean acidification
the carbon dioxide we produce dissolves in the oceans, lowering the pH making it harder for many sea-creatures to build their shells
limiting climate change
reduce emissions of the greenhouse gases by using renewable energy and eating less meat
geoengineering - perhpas placing giant mirrors in space to reflect some of the suns heat
