Fuels Flashcards
what is crude oil
it is a complex mixture of many different kinds of hydrocarbons
how do we separate crude oil into simpler, more useful
mixtures
the process of fractional distillation, where each fraction is a simpler mixture than crude oil
give 6 fractions which are given of in fractional distillation of crude oil, and their uses
1) gases, used in domestic heating and cooking
2) petrol, used as fuel for cars
3) kerosene, used as fuel for aircraft
4) diesel oil, used as fuel for some cars and trains
5) fuel oil, used as fuel for large ships and in some power
stations
6) bitumen, used to surface roads and roofs
describe how hydrocarbons in different fractions differ from each other in the number of carbon and hydrogen atoms their molecules contain
as you go down each fraction, the number of carbon and hydrogen atoms in the molecules increases
describe how hydrocarbons in different fractions differ from each other in their boiling points
as you go down each fraction the boiling points increase
describe how hydrocarbons in different fractions differ from each other in their ease of ignition
as you go down each fraction it is more difficult to set alight
describe how hydrocarbons in different fractions differ from each other in their viscosity
as you down each fraction it becomes more thick and sticky ( higher viscosity).
what does the complete combustion of hydrocarbons involve
it involves the oxidation of hydrocarbons.
what are the products of the complete combustion of hydrocarbons
carbon dioxide + water
what does the complete combustion of hydrocarbons release
it releases energy
what happens in incomplete combustion of hydrocarbons
all the hydrogen atoms become oxidised to fomr water, bu the carbon atoms may form:
- some carbon dioxide
- some carbon monoxide
- some soot (solid particle so carbon)
give the word equation of incomplete combustion of hydrocarbons
methane + oxygen > carbon dioxide + carbon monoxide + carbon + water
explain the problems caused by carbon monoxide
carbon monoxide is a toxic gas. it reduces the amount of oxygen that the blood can carry around the body. breathing in carbon monoxide can kill you
explain the problems caused by soot
soot can: build up in chimneys and eventually cause fires, cause lung diseases, make buildings dirty.
where does incomplete combustion take place in appliances
in vehicle engines, and faulty gas boilers can produce carbon monoxide and soot.
how is sulfur dioxide formed
most hydrocarbon fuels contain impurities such as sulfur. when the hydrocarbons burn, the sulfur is oxidised to form sulfur dioxide
how is acid rain formed
acid rain is formed when sulfur dioxide dissolves in water and makes the water acidic
what are the effects of acid rain
sulfur dioxide, from power stations and vehicles, dissolves in water in the air. rain becomes more acidic than normal. trees are damaged. rivers, lakes and soils are more acidic, which harms organisms living in them. acid rain speeds up the weathering of buildings and statues.
how is the earth warmed
by gases in the atmosphere which trap heat. these gases include carbon dioxide, methane and water vapour.
how does the earth’s temperature vary from human activity
the amount of carbon dioxide affects the temperature change in the atmosphere. the amount of carbon dioxide has increased because humans have been burning fossil fuels and so releasing carbon dioxide into the atmosphere. farming also adds methane to the atmosphere.
giver two ways in which chemists are trying to control the amount of carbon dioxide in the atmosphere,
1) seeding the oceans with iron compounds. this might encourage microscopic plants to grow, which would use carbon in photosynthesis. this carbon would eventually be included into shells and end up in sediments
2) capturing carbon dioxide from power station waste gas and converting it into hydrocarbons to be used as fuels
what are biofuels
fuels obtained from living organisms and can be used instead of fossil fuels.
give 1 example of a biofuel
sugar cane/sugar beet, which can be converted to ethanol. this can be used instead of petrol, and reduces the demand for petrol.
Evaluate the advantages of replacing fossil fuels with biofuels
1) biofuels are renewable
2) biofuels add less carbon dioxide to the atmosphere than burning fossil fuels, because the plants absorbed carbon dioxide from the atmosphere when they grew.
Evaluate the disadvantages of replacing fossil fuels with biofuels
1) growing crops to make into biofuels means that less land is available for growing food. this leads to higher food prices and may lead to some people being short of food.
why are most biofuels not carbon neutral
energy is needed to fertilise, harvest and transport the, crops and to make them into a fuel that can be used in vehicles. this energy usually comes from burning fossil fuels, so some carbon dioxide is added to the atmosphere when the biofuels are produced
what are the 4 factors of a good fuel
1) should burn easily
2) should not produce ash or smoke
3) should release a lot of heat energy
4) should be easy to store and transport
what does a hydrogen fuel cell do
a fuel cell combines hydrogen and oxygen to form water without burning. This reaction releases energy in the form of electricity.
evaluate the advantages of using petrol as a fuel
1) burns easily
2) does not produce ash or smoke
3) releases more energy per kg when it burns, than fuels such as such as coal or wood
4) is a liquid, so it is easy to store and transport
evaluate the disadvantages of using petrol as a fuel
1) produces carbon dioxide and carbon monoxide as well as water when it burns
evaluate the advantages of using hydrogen as a fuel
1) burns easily
2) does not produce ash or smoke
3) only produces water when it burns
4) releases nearly three times as much energy per kg as petrol
evaluate the disadvantages of using hydrogen as a fuel
1) is a gas, so it has to be stored at high pressure
2) filling stations would need to be adapted for hydrogen to be used in cars
give 4 examples of non-renewable fossil fuels
1) petrol, kerosene and diesel oil. they are all obtained from crude oil.
2) methane is a non-renewable fossil fuel found in natural gas
what are alkanes
alkanes are saturated hydrocarbons, which re found in crude oil (natural gas).
give 3 example of alkanes
methane, ethane, propane
what are alkenes
alkenes are unsaturated hydrocarbons, they have a double bond.
give 2 examples of alkenes
ethene, propene
describe the bromine water test.
the bromine test is used to find out if a liquid contains double bonds. bromine water is an orange liquid but becomes colourless when mixed with unsaturated molecules
what are hydorcarbons
they are compounds that contain hydrogen and carbon
