6 markers Flashcards
(6) ) Petrol is the fuel used in many car engines.
Research is being carried out into the use of hydrogen instead of petrol.
Evaluate the advantages and disadvantages of using hydrogen rather than petrol as a
fuel for cars.
Advantages
• plenty of water / raw material
• limited supplies of crude oil
• hydrogen produces only water as waste
• petrol produces carbon dioxide
• carbon dioxide (emissions) may cause global warming
Disadvantages
• hydrogen has to be produced
• requires energy / electricity to produce it
• producing electricity from non-renewable sources produces
carbon dioxide
• expensive to produce
• problems of storage of large volumes of flammable gas
• stronger / heavier / bigger tanks needed
• hydrogen a gas, petrol a liquid, hydrogen leaks more likely
• limited outlets / conversion costs
• shorter distance between refuelling
(6) Explain how the presence of sulfur in fossil fuels can lead to damage to the
environment and how the amount of damage can be reduced.
cause of acid rain • burning sulfur • produces sulfur dioxide • escapes into atmosphere • dissolves in rain water • forming acidic solution / sulfurous / sulfuric acid • falls to the ground as acid rain effect of acid rain • acidification of lakes • kills fish • kills trees / forests • damage / erosion of stonework reduction of damage • calcium carbonate • from limestone • may be converted into calcium hydroxide • waste gases from power stations • passed through carbonate or hydroxide • removing sulfur dioxide
(6) Incomplete combustion of methane can occur in gas heaters such as the one
shown in the photograph.
Explain how incomplete combustion occurs and the problems it can cause.
Production
• lack of / insufficient oxygen
• {blocked burner jets / poor servicing} leads to lack of oxygen
• poor ventilation leads to lack of oxygen
• complete combustion cannot take place
Product
• produces carbon / soot
• produces carbon monoxide
Effects
• wastes fuel
• soot stains / damages decorations etc
• soot causes health problems
• soot may block gas jets
• carbon monoxide is toxic
• combines with haemoglobin / forms carboxyhaemoglobin
• prevents blood carrying oxygen
• no oxygen reaches cells / no respiration / death(6) Evaluate the advantages and disadvantages of using bioethanol, instead of petrol,
as a fuel for cars.
Advantages of bioethanol
• is renewable / petrol is finite / takes a long time to form crude
oil
• crops to make bioethanol regrown quickly/takes a long time to
form crude oil
• use reduces demand on fossil fuels
• carbon dioxide is removed from air when growing crops (which
are used in ethanol production)
• may be sulfur impurities in petrol, none in ethanol / ethanol is
less polluting than petrol (does not produce sulphur dioxide )
• ethanol burns more completely, petrol does not
Disadvantages of bioethanol
• less readily available than petrol / fewer filling stations than for
petrol (in UK but not in some countries)
• lots of crops needed to generate sufficient fuel to replace petrol
• less farmland available for growing food crops
• currently few cars are built to run on bioethanolbioethanol fuel
(in cars) runs out faster / over shorter distances / less energy
efficient
(6) Explain how poly(propene) molecules are formed from propene molecules and
relate the properties of poly(propene) to its uses.
Making the polymer many propene molecules join/react together form a long chain polymerisation reaction propene is the monomer propene is unsaturated / has a double bond poly(propene) has single bonds propene is a gas and forms poly(propene) which is a solid the C=C bond breaks / opens up
Properties of poly(propene) with related uses
e.g.
property – flexible, low density (lightweight), shatterproof, high
softening point, non-toxic, strong, tough, good insulator, water
proof, resistant to corrosion, long lasting, can be moulded into
shape, can be made into fibres
Uses of poly(propene)
use – to make plastic bags, packaging, buckets, bowls, food
containers, ropes, carpets, thermal underwear, Thinsulate
items, toys, bottles, bottle caps, laboratory equipment, medical
equipment, pipes, car bumpers, crates, furniture, tubing
(6) Explain the properties required of a good fuel.
A good fuel should
Burning considerations
• ignite easily
• burn easily
• release a lot of /sufficient heat energy when it
is burnt
Usage considerations
• be safe to use
• be safe/easy to transport
• be {safe/easy/convenient} to store
• be reasonably cheap
Supply considerations
• readily available/good supply
• be renewable/sustainable/not finite
Products considerations
• not produce (much) solid/ash when burnt
• not produce much/any smoke
• contain little/no sulfur
• not produce {toxic/harmful} gases/fumes
• carbon neutral
• not produce too much carbon dioxide or other
named gas such as sulfur dioxide or greenhouse gases(6) Describe the advantages and disadvantages of using bio-methane rather than
natural gas as a source of energy.
advantages
• renewable / sustainable
• more plants can be grown
• crops use up carbon dioxide and produce oxygen
when growing /photosynthesising
• carbon neutral because the carbon produced during
combustion is used when growing the plants
• does not use up crude oil/non-renewable resources
disadvantages
• crops grown for bio-fuels use up land
• land could otherwise be used to provide homes / less
farmland available for growing food crops
• lots of crops required to provide a small amount of
bio-methane
• bad season reduces availability
• carbon emissions due to transport and production if
qualified
(6) Use these results of electrolysis to compare the volumes of hydrogen and oxygen
formed and to show the effect of changing the time and the current on the
volumes of these gases.
Comparing volumes of hydrogen and oxygen
• (in each experiment) volume of hydrogen is twice volume of
oxygen
• because water molecules contain twice as many hydrogen
atoms as oxygen atoms / is H2O
• overall 2H2O → 2H2 + O2
Relating volumes of gases to current and time
• (from experiments 1 and 2) time doubles
• (from experiments 1 and 2) volumes of gases double
• Volumes of gases are directly proportional to the time for
electrolysis / passage of current
• (from experiments 1 and 3) as current x 1.5
• (from experiments 1 and 3) volumes of gases x 1.5
• volumes of gases are directly proportional to the current
(6) The limestone shown in the photograph was originally formed beneath the sea and
then earth movements forced the rock upwards to form the cliff.
Describe how the limestone was originally formed and has become the cliff face
shown in the photograph.
formed from sediments / shells
• sediments fall to the bottom of the sea
• layers of sediment build up on top of one another
• over (very) long time period
• rock formed / compaction
• (caused by)pressure (from the layers above and minerals)
• (cause) the sediment to ‘stick together’
• (to form)layers
• rock movement/change in sea level
• (more recently) rock has been weathered / eroded (by sea)
• because it is a soft rock
