Model
Answers
Chemistry C1
Mr
McDougall
Name: .....................................
Atoms, Elements and Compounds
Explain what the formula Na2CO3 shows about the compound. (2marks)
sodium and carbon and oxygen
all correct numbers linked to correct elements
i.e. 2 (sodium), a / 1 (carbon), 3 (oxygen)
Chemical equations are always balanced. Explain why. (1 mark)
no atoms are lost / made (during a chemical reaction) or
the atoms are rearranged (during a chemical reaction)
accept because of (the law of) conservation of mass / matter
Why is sodium chloride a compound? (2 mark)
two different / types atoms / elements / ions
bonded / joined together
do not accept different size
Why is titanium an element? (1 mark)
all atoms are the same / it only contains one type of atom
accept all ions are the same
do not accept only got one atom
do not accept all atoms are the same size
ignore particles
An atom of argon has 18 protons and 22 neutrons. Work out its atomic number
and its mass number. (1 mark)
The atomic number is 18. The atomic mass is18 + 22 = 40.
Use ideas about electron arrangements to explain why the elements in Group 0
have similar properties. (2 marks)
The highest occupied energy level of each group 0 element contains 8 electrons.
Because there are the same number of electrons in the highest occupied energy level
of each group 0 element, the group 0 elements have similar properties.
How many elements join together to make the compound sodium chloride? (1 mark)
Two – sodium and chlorine
Use ideas about atoms to explain the difference between an element and a
compound. (2 marks)
An element is made up of one type of atom only. A compound consists of atoms of more
than one type.
Explain how sodium and chloride ions are formed when sodium chloride is made
from its elements. (2 marks)
When sodium chloride forms from its elements, one electron is transferred from the
sodium atom to the chlorine atom. This results in a sodium ion with a single positive
charge, Na+, and a chloride ion with a single negative charge, Cl-.
Explain how the atoms in a carbon monoxide molecules are held together. (1 mark)
In carbon monoxide, electrons are shared between the carbon and oxygen atoms.
A molecule of sulphur trioxide consists of one atom of sulfur joined to three atoms
of oxygen. Work out its formula. (1 mark)
SO3
The formula of potassium manganate (VII) is KMnO4. Explain what the formula
tells us about this compound. (2 marks)
In potassium manganate (VII) (potassium permanganate), there are four atoms of
oxygen and one atom of manganese for every one atom of potassium.
Limestone
Limestone is a hard rock that is used as a building material. Limestone was used
by the Egyptians to make plaster. Use the reactions of the lime cycle to explain
how the plaster became even harder with age. (3 marks)
- carbon dioxide / CO 2
- (carbon dioxide) reacts (with the calcium hydroxide / slaked lime / plaster)
- limestone / calcium carbonate /Ca CO 3 forms
- water is lost / evaporates
About 60 million years ago a large meteorite hit the Earth. This meteorite heated
limestone in the Earth’s crust causing the release of large amounts of carbon
dioxide. Explain how carbon dioxide is released from limestone. (2 marks)
calcium carbonate / CaCO3 (1)
decomposed / thermal decomposition (1)
CaCO3 → CaO + CO2 gains 2 marks
How does the limestone used in a power station release carbon dioxide? (1 mark)
(thermal) decomposition
How does the limestone used in a power station remove sulfur dioxide? (1 mark)
calcium carbonate / calcium oxide / limestone / quicklime / it reacts with sulfur dioxide
/ forms calcium sulfate
The use of limestone in a power station releases ‘locked up carbon dioxide’ into the
atmosphere. Explain the meaning of ‘locked up carbon dioxide’. (2 marks)
- (CO2) from the atmosphere
- (CO2) taken in millions of years ago or early (atmosphere)
- (CO2) was used to form the shells / skeletons of marine organisms / fossil fuels
Describe the social, economic and environmental impacts of quarrying limestone.
Explain which impacts are benefits and which are problems. (4 marks)
Environmental problems – takes up land space, making land unavailable for other uses
such as farming and recreation; fuel used in the transport of quarried rock produces
carbon dioxide and other pollutants. Economic benefit – exporting limestone brings in
money for the company, and so contributes to the nation’s economy. Economic problem –
tourism may decline as a result of quarrying, so reducing the income of local amenities.
Social problem – noise and increased traffic in the area around the quarry. Social
benefit – the quarry may create new jobs for local people.
Describe the appearance of cement. (1 mark)
Cement is a grey powder.
List the raw materials used for making mortar and cement. (2 marks)
Mortar – cement, sand, and water;
concrete – cement, sand, aggregate (small stones), water
What happens inside mortar and concrete to make them harden? (2 marks)
Mortar and concrete set when substances in the mixture react with each other.
Describe the pattern shown by the thermal decomposition reactions of metal
carbonates. (2 marks)
The compounds at the top decompose less easily. The decomposition becomes easier as
you go down the reactivity series towards the least reactive metals at the bottom.
Metals
Copper-rich ores are running out. New ways of extracting copper from low grade
ores are being researched. Recycling of copper may be better than extracting
copper from its ores. Explain why. (3 marks)
Any three explanations from:
For recycling
• less acid rain (pollution)
• copper reserves last longer / conserved
Or
 do not run out
• energy for extraction (saved)
or
 less energy required
• less mining / quarrying
• less waste (copper) / electrical
appliances dumped
or
less landfill
Against recycling
• collection problems
• transport problems
• difficult to separate copper from appliances
• energy used to melt the collected copper
What is the meaning of the term ore? (1 mark)
- Contain enough metal to make it economical / worth while to extract
Iron can be produced by reacting iron oxide with carbon in a blast furnace. What
type of reaction produces the iron? (1 mark)
Reduction
List three typical properties of transition metals. (3 marks)
Shiny; easily bent or hammered into shape; good conductors of heat and electricity
Pure iron is relatively soft and not very strong. The iron from the blast furnace is
very hard and brittle. It contains about 4% carbon and is used as cast iron.
Explain the differences in the properties of pure iron and cast iron. (3 marks)
Pure Iron
- (in pure metal all the atoms are the same size and) able to slip / slide over each other
. (property soft)
Cast iron
- (in cast iron) different sized atoms / larger atoms or structure is distorted /
disrupted
- so it is difficult for layers of atoms to slip / slide over each other
What does reduction mean? (1 mark)
removal of oxygen
Give one property of titanium that makes it more useful than steel for hip
replacement joints. (1 mark)
- light(er) / less dense
- resistant to acids / alkalis /chemical
- resistant to corrosion
The use of titanium is limited because it is expensive. Explain why titanium costs
more than steel. (3 marks)
- takes a long time to process
- low abundance (of ore)
- small amount produced
- batch process used or blast furnace is continuous
- more stages used to manufacture titanium
- more energy used (per tonne of titanium)
- labour intensive
Suggest the benefits of recycling aluminium. (3 marks)
- resources / aluminium / ores are conserved
- less / no mining or less associated environmental problems eg quarrying / eyesore /
dust / traffic / noise / loss of land / habitat
- less / no waste (rock) / landfill
- no purification / separation (of aluminium oxide)
- (aluminium extraction / production) has high energy / electricity / heat / temperature
requirements
- less carbon dioxide produced
Pure aluminium is rarely used for the construction of large objects. Small amounts
of other metals are usually mixed with aluminium. Explain why. (2 marks)
Statement (1 mark) link to reason (1 mark)
(pure) Al / it is weak / soft (1) as layers / rows can slide (over each other) (1)
or
alloy / other metals / they makes it stronger / harder (1) stops layers / rows sliding
over each other (1)
Why is iron described as an element? (1 mark)
(because iron is made up of only) one type of atom (not thing)
Suggest why pure iron would not be suitable for a hip replacement joint. (1 mark)
not strong
ignore soft / corrosive / flexible
accept it rusts / corrodes or that it could wear away
accept could change shape / bend
accept layers / atoms could slide (over each other)
Explain why stainless steel is harder than pure iron. (2 marks)
has different sized atoms / particles
or
structure is different/distorted / disrupted
so it is difficult for layers / atoms / particles to slip / slide (over each other)
Suggest how blowing oxygen into molten cast iron removes most of the carbon. (2
marks)
- reacts with carbon / C
- carbon dioxide / CO2 / gas is formed / given off
Why are different metals sometimes added to molten carbon steels? (1 mark)
- change / improve properties
- accept to make alloys
The UK government has set targets for the percentage of iron and steel to be
recycled.
In 2006 the target was exceeded. Suggest two reasons why the UK government
wants to encourage recycling of iron and steel. (2 marks)
- to conserve ores / iron
- to prevent the use of landfills
- to conserve energy / fuel
- to reduce carbon / carbon dioxide emissions
- to meet EU / International targets
Aluminium is the most abundant metal in the Earth’s crust. Suggest two reasons
why we should recycle aluminium drinks cans. (2 marks)
any two from:
- saves resources / nonrenewable
- landfill problem
- saves energy / fuel / electricity
- less carbon dioxide / carbon emissions or reduces carbon footprint
- less quarrying / mining
accept aluminium / ore will run out or conserves aluminium
accept aluminium does not corrode
ignore global warming
ignore consequences of
quarrying / mining
ignore pollution / harms environment / costs / easy to recycle
Titanium is extracted from the titanium chloride by reacting it with sodium at
1000 °C in a reactor. Suggest why the reactor contains argon and not air. (1
mark)
- sodium / titanium would react with oxygen / air
- sodium / titanium does not react with argon
accept air / oxygen is reactive
accept argon is unreactive / inert / a noble gas / in group O
Iron from a blast furnace is called cast iron and contains about 4% carbon. Why
is pure iron softer than cast iron? (1 mark)
layers / atoms in pure iron are able to slide over each other
or
layers / atoms in cast iron are unable to slide over each other (easily)
Steel is made by reducing the percentage of carbon in cast iron and then adding
different metals to form the type of steel required. In the UK we use about 1.8
billion steel cans every year but only 30% of these are recycled. Recycling reduces
waste. Producing steel from recycled cans requires only 25% of the energy needed
to make steel from iron ore. Give three environmental benefits of recycling a
higher percentage of used steel cans. (3 marks)
any three from:
- less iron ore used
- less other metals extracted / used to make different steels
- less fuel used
- less specified pollution
- less / no landfill space needed
- less / no mining needed or fewer specified effects of mining
An ore contains a mixture of zinc carbonate and lead carbonate. Zinc and lead are
produced from this ore by two reactions.
Reaction 1: The carbonates in the ore are converted into a mixture of zinc oxide and
lead oxide. (2 marks)
Name this type of reaction.
(thermal) decomposition
How is this reaction done?
by heating
Reaction 2: The metal oxides are mixed with carbon and heated in a furnace to
produce zinc and lead.
Explain why zinc and lead are produced. (2 marks)
carbon is more reactive than lead / zinc
(so) lead / zinc oxide is reduced or oxygen is removed (by carbon)
Extracting copper from land by the traditional method of quarrying would have a
major environmental impact. Give one reason why. (1 mark)
any one from:
- produces large amounts of solid waste
- atmospheric pollution from carbon dioxide / sulphur dioxide
- more lorries / traffic
It is possible to get copper from a solution of copper sulfate using scrap iron. It
is economical to use scrap iron to get copper. Give one reason why. (1 mark)
iron is cheap
Why can iron be used to get copper from copper sulfate solution? (1 mark)
iron displaces copper from solutions of its salts
accept iron is more reactive than copper
Give two advantages of phytomining compared to the traditional method of
quarrying. (2 marks)
- less expensive/energy to extract the small amounts of copper
- plants will remove carbon dioxide from the atmosphere as they grow
- can release energy when plants are burned
Suggest one disadvantage of phytomining. (1 mark)
not continuous as it takes a long time for plants to grow.
Describe how copper is extracted by phytomining and bioleaching. Give an
advantage of each process. (4 marks)
Phytomining involves planting certain plants on low-grade copper ores. The plants
absorb copper compounds. Burning the plants produces ash that is rich in copper
compounds. An advantage of this process is that it can extract copper from low-grade
ores, which would not be economic to extract in other ways. Bioleaching involves
bacteria, which obtain their nutrients and energy from copper compounds in low-grade
copper ores. The bacteria produce solutions of copper compounds. Chemical reactions
or electrolysis extract copper metals from these solutions. Again, an advantage of this
process is that it can extract copper from low-grade ores, which would not be economic
to extract in other ways.
Use ideas about particles and properties to explain why aluminium alloys are used
in aeroplanes and not the pure metal. (2 marks)
Pure aluminium is not strong enough to be used in aeroplanes. Mixing aluminium with
small amounts of other metals makes alloys. Aluminium alloys are stronger than pure
aluminium because the atoms of the other metals disrupt the regular pattern of atoms
in aluminium, meaning the atoms can slide over each other less easily.
Crude Oil, Fractional Distillation and Hydrocarbons
Crude oil is a mixture of mostly alkanes. Crude oil is separated into useful
fractions by fractional distillation. Describe and explain how the mixture of
alkanes is separated by fractional distillation. (3 marks)
- heat / evaporate the crude oil / change to gas or vapour
- cool / condense (hydrocarbons)
- at different temperatures / boiling points
The C5–C8 fraction has low supply and high market demand. Suggest three ways in
which the oil industry could overcome this problem. (3 marks)
- use different / lighter crude oils
- develop markets for low demand fractions
- develop new techniques / equipment to use low demand fractions as fuels
- cracking
- convert low demand fractions to high demand fractions or bigger molecules to smaller
molecules
- develop alternative / bio fuels
What does unsaturated mean? (1 mark)
(a carbon carbon) double (covalent) bond
accept C = C
accept alkene
Describe the link between the number of carbon atoms in an alkane molecule and
its boiling point. (1 mark)
the greater the number of (carbon) atoms (in an alkane molecule) the greater its boiling
point or vice versa
Crude oil is the source of many useful materials. Crude oil is separated into
fractions by fractional distillation. Describe how the naphtha fraction separates
from the other fractions. (2 marks)
- naphtha has a different / low(er) boiling point
- condenses at a different temperature / height / place in the column / when it reaches
its boiling point
- different size of molecules
Describe how cracking is carried out. (2 marks)
- (hydrocarbon) heated / vapours
- (passed over a) catalyst
Why does ethene have different chemical properties from decane and hexane? (2
marks)
ethene is unsaturated
or decane and hexane / they are saturated
ethene has a double (carbon carbon) bond
or decane and hexane have only single (carbon carbon) bonds
accept decane and hexane are alkanes
or ethene is an alkene / CnH2n
How does the number of carbon atoms in a hydrocarbon affect its boiling point? (1
mark)
The greater the number (of carbon atoms), the higher its boiling point
Describe how crude oil is separated into fractions. (2 marks)
vaporise / evaporate
different condensing points / temperatures
allow boil for vaporise
accept condense at different levels
ignore different size molecules or different densities
allow boils at different temperatures
and condenses for 2 marks
Describe how cracking is carried out. (2 marks)
Boil / vaporise / evaporate
(passed over) a catalyst
Alkanes, such as butane (C4H10), do not form polymers. Alkenes, such as ethene
(C2H4), do form polymers. Explain these statements. (2 marks)
• alkanes / butane (molecules) do not have a (carbon carbon) double bond / are
saturated / have (carbon carbon) single bonds
• alkenes / ethene (molecules) have (carbon carbon) double bonds
or
are unsaturated
• alkenes / ethene molecules are able to bond to other molecules
Explain how crude oil is separated into fractions. You should use the words
evaporated and condensed in your answer. (3 marks)
- crude oil / it is evaporated / vaporised
- vapours / gases / fractions cool and condense
- (different) vapours / gases / fractions (condense) at different temperatures
ignore heated
accept (different) vapours / gases/ fractions have different boiling points
Describe how fuel oil is broken down into smaller, more useful molecules such as
gasoline (petrol). (2 marks)
any two from:
- cracking / (thermal) decomposition
- heat / vaporise
- catalyst
Explain how carbon monoxide is formed. (2 marks)
by incomplete / partial combustion (of the fuel)
insufficient oxygen / air (to burn fuel)
Why does crude oil need to be fractionally distilled? (1 mark)
it is a mixture (of hydrocarbons) or contains hydrocarbons with different boiling points
Describe how cracking is done. (2 marks)
heat / vaporise
catalyst
How are hydrocarbons cracked? (2 marks)
heat / high temperature / hot / vaporise
catalyst
Describe a test to distinguish between an alkane and alkene and give the result of
the test. (2 marks)
add bromine (water)
alkene will decolourise the solutions
or
alkane will not decolourise the solutions
Global Warming and Biofuels
Explain why there would be an environmental problem if the gas sulfur dioxide
from were allowed to escape into the atmosphere. (2 marks)
• sulfur dioxide causes acid rain
• consequence of acid rain eg kills fish / plants
ignore other comments
eg global warming / ozone / global dimming / greenhouse effect
Excess carbon dioxide should be prevented from entering the atmosphere. Explain
why. (2 marks)
- it’s a greenhouse gas or increase greenhouse effect
- causes global warming or increase in the Earth’s temperature
- sea-levels rise or flooding
- climate change
- (polar) ice-caps melt
- extension of deserts
Carbon dioxide is produced when fossil fuels burn in power stations. Use the
diagram to explain how carbon dioxide can be prevented from entering the
atmosphere. (2 marks)
- idea trap / store / lock the carbon dioxide
- in the oil reservoir or under the sea bed
Coal contains carbon and small amounts of sulfur. A steam train would cause
environmental problems if coal were used as the fuel. Explain why. (4 marks)
any two environmental problems with linked explanations
- global warming (1) caused by (formation of) carbon dioxide / greenhouse gas (1)
- acid rain (1) caused by ( formation of) sulfur dioxide (1)
- global dimming (1) caused by ( formation of) particles / particulates / fires / smoke /
carbon / pm 10 (1)
- scarring of landscape (1) caused by mining / quarrying of coal (1)
A steam train would be considered as ‘carbon neutral’ if wood, from the
surrounding forest, were used as the fuel. Suggest why. (3 marks)
any three from:
- replant the trees / renewable /sustainable
- carbon dioxide is used by the trees / photosynthesis
- it’s a (continuous carbon) cycle
- no new carbon (dioxide) is produced or no locked up carbon (dioxide) is released
Many human activities result in carbon dioxide emissions. Our carbon footprint is a
measure of how much carbon dioxide we each cause to be produced. Why should
we be concerned about our carbon footprint? (1 mark)
(thought to cause) global warming / green house (effect) / climate change
ignore other consequences of global warming
do not accept acid rain / ozone layer / global dimming
Most power stations in the UK burn coal. Coal was formed from tree-like plants
over millions of years. Suggest why burning wood instead of coal would help to
reduce our carbon footprint. (3 marks)
any three from:
• replant trees / renewable / sustainable
• carbon (dioxide) used by trees / photosynthesis
• it is a (continuous / carbon) cycle
or
carbon (dioxide) goes back into the air
• no new carbon (dioxide) is produced
or
no locked up carbon (dioxide) is released
or
the carbon (dioxide) was absorbed millions of years ago
ignore reusable
accept trees absorb carbon (dioxide) as they grow
ignore respiration
accept burning wood is carbon neutral
In the UK copper is produced from imported blister copper (98% pure), which has
been extracted from copper ores. In the first stage of purification, air is blown
into molten blister copper to remove any sulfur. The sulfur reacts to form a gas
that should not be allowed to escape into the atmosphere. Explain why. (2 marks)
sulfur dioxide
(forms) acid rain
allow sulfur oxide
accept acidic lakes / seas
ignore consequences
do not accept global warming / global dimming / ozone layer
Why does the release of this carbon dioxide cause an environmental problem? (1
mark)
any one from:
- (increases / enhances) global warming
- is additional carbon dioxide or not able to be absorbed by oceans / seas or used by
(green) plants
- acidification of sea water
Plastics
Explain how propene molecules form a polymer. You should name the polymer
formed. (3 marks)
poly(propene) / polypropene
any two from:
- double bonds open up / break /become single
- propene molecules / monomers /they join / undergo addition polymerisation
- form chains / long molecules
Briefly give one advantage and one disadvantage for each of these methods with
regards to plastics: reuse, recycle, burn, dump (4 marks)
Reused
Advantages:
-saves raw materials / crude oil
- saves energy / fuel / transport
- fewer bags needed / made
- reduces carbon / CO2 emissions
- reduces use of landfill
- saves cost of a new bag
- no waste
Disadvantages:
unable to reuse many times
bags easily split
Recycled
Advantages:
- saves raw materials / crude oil
- saves energy / use of fuel
- reduces carbon / CO2 emissions
- reduces use of landfill
- can be used for new products
Disadvantages:
- has to be collected /transported / washed / separated / melted
ignore uses energy
Burned
Advantages
- heat / energy released can be used (for heating / generating electricity)
- reduces use of landfill
Disadvantages
- has to be collected / transported
- wastes the resource / plastic
- releases harmful gases / toxic gases / CO2
Dumped
Advantages
- collected / transported with household waste
- (slowly) biodegrades or produces methane which can be used as a fuel
- (not biodegradable so) does not release CO2 / green house gas into the air
- wastes the resource
Disadvantages
- plastic uses landfill
- produces methane which is a greenhouse gas / could cause explosions
- not biodegradable / take years to decompose
You are asked to decide which option for the disposal of poly(ethene) will be put
forward in your area. You decide that recycling is the best option. Suggest one
economic argument and one environmental argument that will be made against
recycling. For each argument made, how will you persuade those making the
argument to accept your option?
(You must use only one sentence for each argument made against your decision and
only one sentence for your response to it.) (4 marks)
economic argument against recycling
any one from:
- poly(ethene) / plastic must be collected / transported / sorted / washed
- this uses (fossil) fuels which are expensive
environmental argument against recycling
any one from:
- uses (fossil) fuels that are non-renewable / form CO2 / CO / SO2 /NOx /
particulates
- washing uses / pollutes water
counter arguments
any two from:
- collect / transport alongside other waste
- use biofuels (instead of fossil)
- landfill is running out
- landfill destroys habitats
- incinerators are expensive to build
- saves raw materials / crude oil
- saves energy needed to make new plastic
- incinerators may produce harmful substances
- incinerator ash goes to landfill
- poly(ethene) is non-biodegradable
- poly(ethene) can be made into other useful items
- more jobs / employment for people
Describe how ethene forms poly(ethene). (2 marks)
many ethene / molecules / monomers
join to form a long hydrocarbon / chain / large molecule
accept double bonds open / break
accept addition polymerisation
ignore references to ethane
PEX is a shape memory polymer. What property does a shape memory polymer
have? (1 mark)
(can be deformed but) return to their original shape (when heated or cooled)
PEX is a material that is used as an alternative to copper for hot water pipes.
PEX is made from poly(ethene). Suggest the possible environmental advantages of
using PEX instead of copper for hot water pipes. (4 marks)
any four from:
- less (hydrocarbon) fuels used
- less / no electrical energy used
- reduce carbon / carbon dioxide emissions
- reduce / no pollution by sulfur dioxide / acid rain
- continuous process
- conserve copper which is running out or only low-grade ores available
- reduce the amount of solid waste rock that needs to be disposed
- reduce the need to dig large holes (to extract copper ores)
allow less energy
allow no electrolysis
allow less global warming
allow less / no transportation
allow less waste
allow less mining
Give two reasons why a company would decide to increase the amount of hydrogel
used in its nappy pads. (2 marks)
any two from:
- it was not the best (at absorbing the water)
- (needed) to absorb more (water)
- to improve their image / sales
Suggest one disadvantage for the company if it increases the amount of hydrogel
used in its nappy pads. (1 mark)
- cost (more)
- use (more) resources
- use (more) energy
Poly(ethene) molecules are made from ethene molecules by a polymerisation
reaction. Describe what happens in a polymerisation reaction. (2 marks)
many (ethenes / monomers)
bond / join together
Explain why different polymers have different properties. (1 mark)
Different polymers have different properties because their molecules are made up of
different chemicals and are arranged in different ways
List one use each for LDPE and HDPE. Explain how the properties of each of these
polymers make them suitable for these uses. (4 marks)
LDPE – packaging; suitable because it is flexible and waterproof.
HDPE – garden furniture; suitable because it is rigid and waterproof
Suggest two advantages of filling your teeth with a white polymer and not a
mixture of metals. (2 marks)
The colour matches that of teeth. The material conducts heat less well than metals, so
eating hot or cold food is not painful.
Use ideas about particles to explain why HDPE is stronger and has a higher melting
point than LDPE. (2 marks)
HDPE polymer molecules have fewer side branches than LDPE, so HDPE molecules line
up in a pattern close together. This means the molecules are held together more
strongly in HDPE than in LDPE, so HDPE is stronger and has a higher melting point
Ethanol
Ethanol can be made using either sugar or alkenes as the starting material.
Evaluate the advantages and disadvantages of using these two starting materials to
produce ethanol. (4 marks)
Candidates must include both sugar cane and crude oil in their evaluation and both an
advantage and a disadvantage to gain full marks. If they do not then the maximum mark
is three.
any four from:
advantages of using sugar
• country has no wealth to buy (large quantities of) crude oil
• country has limited technological development
or
underdeveloped / third world country
• able / suitable climate to grow sugar cane
• enough land to grow sugar cane / land cannot be used to grow food / deforestation
• sugar is a renewable source
or
crude oil is a non-renewable resource / finite resource / limited resources
• CO2 / carbon neutral
advantages of using alkenes:
• economic costs are low
• continuous process
• country has large oil resources
• country has oil refineries / cracking plants
• very pure product
• faster process
Ethanol, for use as a fuel, can also be produced from food crops. Evaluate
whether more of this ethanol should be produced from food crops or from crude
oil. Remember to give a conclusion to your evaluation. (5 marks)
advantages eg:
- renewable (resource) / sustainable
- low / less energy / fuel needed for process or lower temperature
[ignore heat or quoted temperatures]
- can use waste plant / crop material
- carbon neutral
- low safety risk (processes)
- low technology
disadvantages eg:
- batch process / process is slow
- many steps in the process
- ethanol is impure / may contain water
- food shortages
- need very large areas of (arable) land to grow crops or can only grow in certain areas
/ climates
- destruction of woodland / habitat
- slow growth of crops
- labour intensive
a conclusion with a reasoned argument based on
Describe and explain the problems associated with producing and using hydrogen
and ethanol fuels. (4 marks)
Hydrogen must be manufactured from methane or water. The processes require large
amounts of energy and put carbon dioxide into the atmosphere. Storing and
transporting hydrogen fuel – an explosive gas – is difficult, dangerous, and expensive.
Ethanol fuel is manufactured from sugar cane or other crops. Although the growing
crops remove carbon dioxide from the atmosphere, producing fertilisers and
manufacturing ethanol from the plant material both release carbon dioxide to the
atmosphere. Some people think that it is unethical to use land to grow fuel instead of
food.
Hydrogenation and Emulsions
The ingredients of soft margarine include hydrogenated vegetable oil. Why is
hydrogenated vegetable oil used in soft margarine? (1 mark)
any one from:
• have a higher melting point than (vegetable) oil
• are solid at (room temperature) /hardened / harder
Describe how vegetable oils are hydrogenated. (2 marks)
any two from:
• hydrogen added
• to carbon carbon double bond / to saturate
• (nickel) catalyst / temperature 60 - 150°C
What type of fat contains double carbon carbon bonds? (1 marks)
(poly)unsaturated
Unsaturated vegetable oils can be hardened to make them useful as spreads.
Describe how unsaturated vegetable oils are hardened. (2 marks)
(react) with hydrogen / H2 /hydrogenation
any one from:
- heated / 60°C
- catalyst / nickel
What do the E-numbers indicate? (1 mark)
permitted additive / (added) chemicals
or
names / types of additives
To detect unsaturated fats, a small amount of bromine or iodine solution can be
added. What happens to show that an unsaturated fat is present? (1 mark)
turns colourless / decolourises
Sunflower oil can be hardened so that it can be used to make margarine. Explain
how sunflower oil can be hardened. (3 marks)
any three from:
- (react with) hydrogen
- with a (nickel) catalyst
- at about 60°C
- increase the melting point
Oils can be hardened by reacting them with hydrogen. A student said that
hardening would make sunflower oil healthier. Is this student’s hypothesis correct?
Explain your answer. (2 marks)
no, because hydrogen adds to the unsaturated fat or no, because hydrogen reduces the
number of carbon.carbon double bonds
therefore there will be less polyunsaturated fat
Explain how the molecules in the egg yolk are able to produce a stable mixture of
olive oil and water. (3 marks)
molecules in egg yolk act as emulsifiers
because molecules in egg yolk have a head which dissolves in / attracted to water
because molecules in egg yolk have a tail which dissolves in / attracted to oil
Describe the property of emulsions that makes them suitable for salad dressings.
(1 mark)
They have good coating ability and a thick texture.
Explain why plants make and store oils. (2 marks)
Oil and water do not mix well because the long hydrocarbon chains in the oils cannot
interact with water molecules, which do not have long hydrocarbon chains.
Explain how emulsifiers stop oil and water separating out in emulsions. (4 marks)
Emulsifier molecules have two different ends. One end interacts well with water
molecules. This is the hydrophilic end. One end interacts well with oil molecules, and
badly with water molecules. This is the hydrophobic end. In an oil-in-water emulsion,
emulsifier molecules coat the surface of oil droplets. The hydrophobic ends of the
emulsifier molecules interact with the oil droplets. The hydrophilic ends interact with
the water. These coatings keep the oil droplets evenly dispersed throughout the
emulsion and stop them clumping together to form their own separate layer.
Biofuels and Plant Oils
Use your knowledge explain the environmental benefits of using biodiesel as a
sustainable, low pollution fuel. (3 marks)
sustainable:
maximum two from:
- crops (that produce oil) can be grown in most places
- renewable
- use less fossil fuels / diesel
- use (refined) waste oils
low pollution:
maximum two from:
- most emissions are lower or any two named emissions from CO / SO2 / PM10 are
lower
- much / lot less SO2 emissions (than the others)
- accept spillages / waste is biodegradable
- less new CO2 or (more) carbon neutral
Biodiesel is called a green fuel. This is because the life-cycle emission of carbon
dioxide from biodiesel is less than that from fossil diesel. Use your knowledge to
explain why biodiesel’s contribution to global warming is considered to be much less
than that of fossil diesel. (3 marks)
- plants / photosynthesis use carbon (dioxide) from the air
- biodiesel releases carbon (dioxide) from plants / crops / photosynthesis
- (fossil) diesel releases .locked up. / new carbon (dioxide) / doesn’t absorb CO2 /
absorbed it millions of years ago
Carbon monoxide can be produced when diesel burns in a car engine. Explain how.
(2 marks)
carbon / diesel / it reacts / burns in oxygen / air
limited supply (of oxygen / air)
accept incomplete combustion
Evaluate the use of biodiesel compared with fossil diesel as a fuel for cars.
Remember to give a conclusion to your evaluation. (5 marks)
any four from:
for biodiesel:
- less global dimming (because fewer carbon particles)
- less acid rain (because less sulfur dioxide)
- renewable resource / sustainable
- use waste vegetable oils / fats
- vegetables / plants absorbed carbon dioxide / carbon neutral
- uses land which could be used to produce food
- third world countries can produce bio diesel
- biodegrades easily
- more NOx released
justified conclusion
accept converse statements for fossil diesel.
ignore cost / ease of manufacture / usage issues
accept fossil fuel / diesel supplies are limited
accept fossil fuel / diesel releases locked up carbon / is not carbon neutral
Evaluate the use of plant oils to produce biodiesel. Remember to give a conclusion
to your evaluation. (5 marks)
Arguments for biodiesel
max three from:
• sustainable / renewable
• (carbon neutral) absorbs CO2 when growing / during photosynthesis
• burning biodiesel produces low amounts particulates / carbon monoxide
• can use waste vegetable oils / fats (from food industry) or can use waste plant
material
• can be used to conserve crude oil (instead of / mixed with petroleum diesel)
• produced by a low energy / temperature process
• biodegrades (easily)
Arguments against biodiesel
max three from:
• creates food shortages
• deforestation to plant more crops leads to loss of habitat / biodiversity or
deforestation leads to a reduction in absorption of CO2
• burning biodiesel produces high amounts of nitrogen oxides
• crops takes time to grow
• vast areas of land needed to grow crops
conclusion supported by the argument presented, which must give added value to the
points for and against given above
The Earth
Earthquakes within the Earth’s crust can be sudden and disastrous. Scientists
cannot accurately predict when earthquakes will occur. Explain why. To obtain full
marks you must support your answer with a description of what causes
earthquakes. (4 marks)
plate (boundaries)
sudden movement / colliding
or
normally move a few centimetres per year
convection currents / driven by heat from
radioactive processes / decay
the idea of uncertainty with an explanation
eg scientists do not know (with any certainty)
• what happens under the crust
• where the forces / pressure are building up
• we cannot measure the forces
• when the forces reach their limit
(accept continental drift)
Two hundred years ago, scientists thought that the Earth was about 400 million
years old. This estimate came from the idea that the centre of the Earth was
still molten. More recently, measurement of radioactivity in rocks has shown that
the Earth is much older than 400 million years. Suggest one reason why scientists
now know that the Earth is much older than
400 million years. (1 mark)
Radioactivity (keeps the core hot)
Accept the Earth is not cooling
do not accept fossil / rock evidence
Suggest two pieces of evidence that could be used to show that the continents had
once been joined (2 marks)
 the shapes of the two continents fit together (like a jigsaw)
 the same type of rocks have been found
 the same fossils have been found
 rising magma rising through a gap under the Atlantic
About fifty years ago, new evidence convinced scientists that the Earth’s crust is
made up of tectonic plates that are moving very slowly.
Give two pieces of evidence that have helped to convince these scientists that the
tectonic plates are moving. (2 marks)
- earthquakes
- volcanoes
- idea of distance between America and Europe / Africa is increasing e.g.continental
drift
- oceanic ridges
- formation of (new) mountain ranges
- formation of (new) islands
- magnetic stripes
- tsunamis
Suggest two reasons why the other scientists in 1920 thought that Wegener was
wrong. (2 marks)
- continents / plates cannot move (thousands of kilometres)
- modern / new animals are different
- a land bridge (could explain the matching fossils / rocks)
accept the continents / plates are attached to the Earth or continents / plates cannot
drift / float
ignore .no evidence/no proof
Explain how earthquakes are caused. (3 marks)
Movement of (tectonic) plates
any two from:
- vibration / (shock)waves (in the earth)
- caused by convection currents (in the mantle)
- heat / energy released from radioactive processes
In terms of what is happening within the Earth, explain the problems of trying to
predict earthquakes. (2 marks)
scientists do not know:
- what happens under the crust / mantle / under the surface
- where forces / pressures are building up
- how to measure these forces / pressures
- when these forces / pressures reach their limit
Describe what causes the Earth’s tectonic plates to move. (3 marks)
in the mantle
any two from:
- convection (currents) / movement
- radioactivity / radioactive decay / nuclear reactions
- releases heat / thermal energy
Give one reason why Wegener’s idea was not accepted in 1915. (1 mark)
no / insufficient evidence / proof / explanation
accept there were other theories such as a land bridge / solid crust
The theory of plate tectonics is used to explain why earthquakes occur. Explain
how earthquakes occur. (2 marks)
(continental / tectonic) plates move
any one from:
• (caused by) convection currents (in the mantle)
• (driven by) heat (energy) released by radioactive processes / decay
• sudden (movement) / vibrations
Suggest why it is difficult to predict when an earthquake will occur. (1 mark)
• do not know / see / able to detect / measure what is happening below the Earth’s
crust
• build up of pressure between plates is randomly released
In 1915, Alfred Wegener had an idea that the change shown in the diagram was
caused by continental drift. Most scientists could not accept his idea. Suggest why
most scientists in 1915 could not accept Wegener’s idea of continental drift. (1
mark)
- Wegener had no evidence / proof
- other scientists had different ideas / views
- did not respect Wegener as a scientist / geologist
accept movement too slow to measure
accept continents / plates fixed or land bridge
The Earth has a layered structure and is surrounded by an atmosphere. Use this
information and your knowledge and understanding to explain how continents move.
(3 marks)
any three from:
- plates (move)
- heat energy / radioactivity (causes)
- convection currents
- in mantle
Scientists have suggested that the Earth consists of a core, mantle and crust. A
‘traditional’ theory is that the core is made of iron and nickel. A ‘controversial’
theory is that the core is like a nuclear reactor made of the radioactive elements
uranium and plutonium. Why can scientists not prove which theory about the core
is correct? (1 mark)
cannot get to / reach / drill to / see the core
accept the core is (too) far down (into the Earth) / do not know what happens under
the crust / Earth’s surface
accept it is (too) hot / radioactive
Suggest two pieces of evidence that may have led Wegener to propose his
hypothesis that continents move. (2 marks)
- the continents of South America and Africa would have fitted together like a jigsaw
- there are matching / similar rocks / fossils on the continents of South America and
Africa
Suggest why, in 1920, other scientists thought that Wegener’s hypothesis was
wrong. (2 marks)
other scientists thought that continents are fixed / cannot float or Wegener had no
evidence to prove that continents can move
a land bridge could explain the matching / similar rocks / fossils on the continents of
South America and Africa
The Atmosphere
Suggest what has caused the main gases in the Earth’s atmosphere of millions of
years ago to change to the present-day atmosphere. (2 marks)
any two from:
carbon dioxide has decreased due to:
- plants / micro organisms /bacteria / vegetation / trees
- photosynthesis
- locked up. in (sedimentary) rocks / carbonates / fossil fuels
- dissolved in oceans
oxygen has increased due to:
- plants / bacteria / microorganisms / vegetation / trees
- photosynthesis
nitrogen increased due to:
- ammonia reacted with oxygen
- bacteria / micro organisms
There is evidence that the composition of the Earth’s atmosphere is still changing.
One possible reason is that many power stations generate electricity by burning
fossilfuels such as coal, oil or natural gas. Sulfur dioxide, SO2, is produced when
coal burns in air.
(i) What environmental problem does sulfur dioxide cause? (1 mark)
acid rain
(ii) How could this environmental problem be reduced in coal-fired power stations?
(1 mark)
idea of the removal or use of sulfur dioxide gas (from the waste gases)
The Earth’s atmosphere today contains about 0.035 % carbon dioxide. What
happened to most of the carbon dioxide that was in the Earth’s early atmosphere?
(2 marks)
any two from:
- used by plants
- used for photosynthesis
- absorbed / dissolved in oceans
- locked up in fossil fuels / limestone / sedimentary rocks
Explain what has happened to most of the water vapour in the Earth’s early
atmosphere. (2 marks)
condensed
formed the oceans / seas
accept temperature went below 100°C / boiling point of water
allow cooled to form liquid / water / rain
do not accept evaporated
Give two reasons why the percentage of carbon dioxide in the Earth’s early
atmosphere decreased. (2 marks)
-
used by (green) plants / algae
changed into oxygen
dissolved in oceans / seas
(locked up) in carbonates / sedimentary rocks
(locked up) in fossil fuels
Describe how the evolution of plants changed the Earth’s atmosphere. (2 marks)
- photosynthesis
- carbon dioxide used
- oxygen produced
Where did the carbon that is locked up in fossil fuels come from? (1 mark)
(carbon dioxide in the Earth’s early) atmosphere
accept from volcanoes (millions of years ago)
or from dead plants / animals
allow dead sea creatures
The burning of fossil fuels has caused the percentage of carbon dioxide in the
atmosphere to increase to above 0.03 %. Explain why. (2 marks)
increase in burning / use of fossil fuels
locked up carbon (carbon dioxide)
Explain the origin of atmospheric oxygen. (2 marks)
Produced as a waste product from photosynthesis in early plants
Explain why we cannot be sure how the Earth’s atmosphere was formed. (1 mark)
No one was around to record events as they happened.
Describe the primordial soup theory of the origin of life and the experimental
evidence that supports it. (3 marks)
The primordial soup theory suggests that gases in the early atmosphere reacted with
each other in the presence of sunlight to make complex molecules that are the basis of
life. In 1953, scientists simulated a lightning spark in a mixture of the gases of the
early atmosphere. A week later, more than 2% of the carbon in the system had formed
compounds from which proteins in living cells are made. This supports the primordial
soup theory, according to the scientists who did the experiment.
Air is a mixture of gases. The air is filtered before the gases are separated.
Suggest why. (1 mark)
to remove solid / dust particles