fuels and earth science Flashcards
examples of non renewable resources
fossil fuels - coal, oil, gas
what is crude oil separated into
different hydrocarbon fractions
facts about crude oil
- main source of hydrocarbons
- used as a raw material
- formed underground over millions of years
- complex mixture of lots of different hydrocarbons
- can be separated out into fractions e.g. petrol, diesel
how is crude oil separated
fractional distillation
how does fractional distillation of crude oil work
oil is heated until most of it has turned into gas
gas enters a fractionating column & liquid is drained off
in the column there is a temperature gradient,
longer hydrocarbons have a higher boiling point and short hydrocarbons have a lower boiling point
you end up with crude oil mixture separated into different fractions
what is at the bottom of the fractional distillation tank (the hottest part)
bitumen
how many hydrocarbons does bitumen have
70 +
what is bitumen used for
surface roads and roofs
what’s about bitumen in the tank
fuel oil
how may hydrocarbons does fuel oil have
40
what is fuel oil used for
fuel for larger shops and some power stations
what’s about fuel oil in the tank
diesel oil
how many hydrocarbons does diesel have
20
what is diesel used for
fuel some cars and larger vehicles e.g. trains
what’s about diesel in the tank
kerosene (paraffin)
how many hydrocarbons does kerosene have
15
what are some used of kerosene
fuel in aircraft
what is above kerosene in the tank
petrol
how many hydrocarbons does fuel have
8
what is petrol used for
fuel in cars
what is at the top of the tank above petrol (coolest part)
gases
how many hydrocarbons do gases have
3
what are the uses of gases
domestic heating and cooking
what do all compounds in a homologous series share
similar chemical properties and general formula
why do the physical properties vary
the bigger the molecule the higher the boiling point will be
what is methanes molecular formula, boiling point and fraction in crude oil
CH4
-162
gases
what is ethanes molecular formula, boiling point and fraction in crude oil
C2H6
-89
gases
what is dodecanes molecular formula, boiling point and fraction in crude oil
C12H26
216
kerosene
what is icosanes molecular formula, boiling point and fraction in crude oil
C20H42
343
diesel oil
what is tetracontanes molecular formula, boiling point and fraction in crude oil
C40H82
524
fuel oil
why do intermolecular forces break more easily in small molecules than larger
because the forces are much stronger between big molecules than small molecules hence why big molecules have higher boiling points than small molecules
why are short hydrocarbons easy to ignite
they have lower boiling points so tend to be gases at room temp
why are longer hydrocarbons harder to ignite
they are usually liquid at room temp and have higher boiling points
viscosity
have easily a substance flows
what does a stronger force between hydrocarbons molecules have in viscosity
makes it harder to flow, they are one treacle
what does a weaker force between hydrocarbons molecules have in viscosity
low viscosity- much more runny
what do you get when you burn fossil fuels
carbon monoxide, oxides of nitrogen and sulphur dioxide
what does complete combustion produce
carbon dioxide and water
what does incomplete combustion produce
toxic carbon monoxide and soot
how is incomplete combustion caused
not enough oxygen around for complete combustion
how is carbon monoxide toxic
can combine with red blood cells and stop your blood from doing its proper job of carrying oxygen round the body
the lack of oxygen can cause fainting, coma and death
what happens during incomplete combustion
tiny particles of carbon are relaxed into the air, as they fall back onto the ground, they deposit themselves as soot
why is soot bad
makes buildings look dirty, reduces air quality, can worsen respiratory problems
what does sulphur dioxide cause
acid rain
how is acid rain caused
fossil fuels are burned, they release mainly carbon dioxide however they also release harmful gases such as sulphur dioxide
sulphur dioxide comes from sulphur impurities in fossil fuels
sulphur mixes with clouds and forms dilute sulphuric acid , falls as acid rain
how does acid rain damage the environment
acid rain causes lakes to become acidic when it falls, harming/killing plants and animals
acid rain also damages limestone buildings and stone statues as well as causing metal to corrode
how are nitrogen oxides harmful pollutants
they contribute to acid rain and photochemical smog
photochemical smog
type of air pollution and can cause breathing difficulties
how is hydrogen gas made and how can it be used
it’s obtained from water and then hydrogen combines with oxygen it can be used to power vehicles, often used in fuels as fuel cells
pros of hydrogen gas fuel
very clean fuel
only waste product is water - nothing harmful
renewable source as it’s obtained from water
cons of hydrogen gas fuel
needs a special, expensive engine
expensive to obtain
hard to store
what is cracking
splitting up long chain hydrocarbons by turning long saturated molecules into smaller unsaturated molecules
what is cracking a form of
thermal decomposition
what is thermal composition
when one substance breaks down into at least 2 new ones when you heat it - means breaking strong covalent bonds
what does cracking produce
lots of alkene molecules - can make polymers
what does cracking involve (3)
heat, moderate pressures and a catalyst
what does cracking help with
supply and demand
how is there evidence that our atmosphere has changed
evidence from rocks, bubbles in ice and fossils
what happened during phase 1 of the atmosphere
volcanoes gave out steam or CO2
- there was originally no atmosphere
- earths surface cooled, thin crust formed
- volcanoes kept erupting releasing gas inside earth
- eventually things settled however the atmosphere was mainly CO2 - very little oxygen
- water vapour condensed to form ocean
what happened during phase 2 of the atmosphere
green plants evolved to produce oxygen
- co2 dissolved into the oceans
- nitrogen was then put into the atmosphere
- green plants evolved over most of the earth - photosynthesised
- air gradually built up due to the plants
what happened during phase 3 of the atmosphere
ozone layer allowed evolution of complex animals
- build up of oxygen caused early organisms to die
- allows evolution of more complex organisms
- oxygen created the ozone layer, blocked harmful rays of sun so organisms could evolve
- virtually no CO2 left
what is the test for oxygen
if the gas will relight a glowing splint
what affects the composition of air
human activity
what is human activity which effects composition of air
- population increase
- more energy demand - means burning more fossil fuels
- industrialisation
- deforestation - let’s out trapped CO2 to environment
- volcanoes erupting
what does the green house effect do
keeps the earth warm by absorbing the electromagnetic radiation of the sun, warming the planet
what are greenhouse gases
gases which are in the atmosphere which can absorb and reflect heat radiation, only present in small amounts
what does increasing greenhouse gases cause
climate change
what are the green house gases
carbon dioxide
water vapour
methane
what is the enhanced greenhouse effect
where greenhouse gases increase
why is methane an issue to enhancing greenhouse gases
concentration has risen due to increased human activity in farming where animals produce methane through digestive processes
what is global warming
a type of climate change which causes other types of climate change
how does global warming work
extra greenhouse gases from human activity have caused the average temperature of the earth to increase
what’s another version of climate change
changing rainfall patterns
what do most scientists believe
global warming is anthropogenic (human caused)
why is historical data much less accurate than current records
- less representative of global levels - old data could only be taken by fewer locations while now we can go anywhere over the world
- methods were less accurate
- there are no records if you go back far enough, so it’s estimated however it’s less precise
what can we do to slow down climate change
try to use less fossil fuels to reduce our carbon emission
find more renewable resources such as wind or solar power
