Crude Oil and Fuels and Useful Substances From Crude Oil c1 Revision Higher

8/19/2019 Crude Oil and Fuels and Useful Substances From Crude Oil c1 Revision Higher

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Crude oil and fuels and Useful substances fromcrude oil

C1 Revision (higher)

114 minutes

114 marks

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Q1. Barbecues are heated by burning charcoal or burning hydrocarbons.

(a) Use the Chemistry Data Sheet to help you to answer this question.

The chemical equation for charcoal burning is:

C + O2 CO

2

Complete the word equation for this reaction.

carbon + ................................... carbon dioxide

(1)

(b) Propane is a hydrocarbon.

(i) Complete the displayed structure of propane. Draw in the missing bonds.

(1)

(ii) Write the chemical formula of propane. .................................................. (1)

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(ii) Fuels react with oxygen to produce carbon dioxide. The reaction of a fuel with oxygen can produce a different oxide of carbon.

Name this different oxide of carbon and explain why it is produced.

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(b) Most of the compounds in crude oil are hydrocarbons. Hydrocarbons with the smallest molecules are very volatile.

In this question you will be assessed on using good English, organising information clearlyand using specialist terms where appropriate.

Describe and explain how petrol is separated from the mixture of hydrocarbons in crudeoil.

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Use the diagram and your knowledge to answer this question.

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(Total 9 marks)

Q3. This question is about oil reserves.

(a) Diesel is separated from crude oil by fractional distillation.

Describe the steps involved in the fractional distillation of crude oil.

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(b) Diesel is a mixture of lots of different alkanes .

What are alkanes ?

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(c) In this question you will be assessed on using good English, organising information clearlyand using specialist terms where appropriate.

Petroleum products, such as petrol, are produced from crude oil.The graph shows the possible future production of petroleum products from crude oil andthe expected demand for petroleum products.

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Canada’s oil sands hold about 20% of the world’s known crude oil reserves.

The oil sands contain between 10 to 15% of crude oil. This crude oil is mainly bitumen.

In Canada the oil sands are found in the ground underneath a very large area of forest. Thetrees are removed. Then large diggers and trucks remove 30 metres depth of soil and rockto reach the oil sands. The oil sands are quarried. Boiling water is mixed with the quarriedoil sands to separate the bitumen from the sand. Methane (natural gas) is burned to heatthe water.

The mixture can be separated because bitumen floats on water and the sand sinks to thebottom of the water. The bitumen is cracked and the products are separated by fractionaldistillation.

Use the information given and your knowledge and understanding to suggest theadvantages and disadvantages of extracting petroleum products from oil sands.

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(Total 11 marks)

Q4. Crude oil is a mixture of mostly alkanes.

(a) Crude oil is separated into useful fractions by fractional distillation.

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(i) Describe and explain how the mixture of alkanes is separated by fractionaldistillation.

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(ii) The table gives the name and formula for each of the first three alkanes.

Complete the table to show the formula of butane.

(1)

Name of alkane Formula

Methane CH4

Ethane C2H

6

Propane C3H

8

Butane

(b) The structural formula of methane, CH4, is:

H │

H C H │ H

Draw the structural formula of propane, C3H

8

(1)

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(c) The relative amounts of and the market demand for some hydrocarbons from thefractional distillation of crude oil are shown in the graph.

(i) Why is the market demand for the C5 – C

8 fraction higher than the market demand for

the C21 – C

24 fraction?

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(ii) Cracking is used to break down large hydrocarbon molecules into smallerhydrocarbon molecules.

Complete the symbol equation by writing in the formula of the other hydrocarbon.

C20

H42 C

16H

34 + 2 ..........................................

(1)

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(iii) The C5 – C

8 fraction has low supply and high market demand.

Suggest three ways in which the oil industry could overcome this problem.

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(Total 10 marks)

Q5. 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.

(a) Why should we be concerned about our carbon footprint?

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(b) 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.

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(Total 4 marks)

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Q6. Crude oil is a mixture of hydrocarbons. Most of these hydrocarbons are alkanes.

(a) The general formula of an alkane is CnH

2n+2

Complete the structural formula for the alkane that has six carbon atoms in its molecules.

(1)

(b) The boiling points of alkanes are linked to the number of carbon atoms in their molecules.

(i) Describe the link between the number of carbon atoms in an alkane molecule and itsboiling point.

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(ii) Suggest two reasons why all of the alkanes in the bar chart are better fuels than thealkane with the formula C

30H

62

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(c) During the last 200 million years the carbon cycle has maintained the percentage ofcarbon dioxide in the atmosphere at about 0.03 %. Over the last 100 years the percentage of carbon dioxide in the atmosphere has increasedto about 0.04 %. Most of this increase is caused by burning fossil fuels to heat buildings, to generateelectricity and to power our transport. Fossil fuels contain carbon that has been locked up for millions of years.

(i) Burning fossil fuels, such as petrol, releases this locked up carbon. Balance the

chemical equation for the combustion of one of the alkanes in petrol.

(1)

2 C8H

18

+ 25 O

2

........ CO

2

+ ........ H

2O

(ii) Where did the carbon that is locked up in fossil fuels come from?

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(iii) The burning of fossil fuels has caused the percentage of carbon dioxide in theatmosphere to increase to above 0.03 %. Explain why.

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(Total 8 marks)

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Q7. Petroleum diesel is produced from crude oil.

Most vehicles that use petroleum diesel as fuel can also use biodiesel or a mixture of these two fuels. Inthe UK (in 2010) there must be 5 % biodiesel in all petroleum diesel fuel.

Biodiesel is produced from plant oils such as soya. The crops used to produce biodiesel can also beused to feed humans. The benefit that biodiesel is ‘carbon neutral’ is outweighed by the increasingdemand for crops. This increasing demand is causing forests to be burnt to provide land for crops to

produce biodiesel. Only a huge fall in the price of petroleum diesel would halt the increasing use ofbiodiesel.

The graph shows the average percentage change in exhaust emissions from vehicles using differentmixtures of petroleum diesel and biodiesel.

There is no difference in carbon dioxide emissions for all mixtures of petroleum diesel and biodiesel.

Use the information and your knowledge and understanding to evaluate the use of plant oils to producebiodiesel.

Remember to give a conclusion to your evaluation.

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(Total 5 marks)

Q8. The table shows how much carbon dioxide is produced when you transfer the same amount

of energy by burning coal, gas and oil.

(a) Use the information from the table to complete the bar-chart.(2)

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(b) The second bar-chart shows how much sulphur dioxide is produced by burning the samethree fuels.

Compare the amount of sulphur produced by burning gas with the amount produced byburning coal.

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(c) Burning fuels also produces nitrogen oxides, even though the fuels contain no nitrogen.Explain why this happens.

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(d) When you release the same amount of energy from coal, gas and oil, different amounts ofcarbon dioxide are produced. Use the information below to explain why.

(3)

(e) What other element do coal and oil usually contain?

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(Total 9 marks)

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Q9. Crude oil is used to produce poly(ethene).

(a) Fractional distillation is used to separate crude oil into fractions.

(i) Write a number, 2, 3, 4 or 5, next to each stage so that the description of fractionaldistillation is in the correct order. Numbers 1 and 6 have been done for you.

(2)

Number Stage

1 The crude oil is heated to 350 °C.

When a fraction in the vapours cools to its boiling point, the fractioncondenses.

Any liquids flow down to the bottom of the column and the hotvapours rise up the column.

6 The condensed fraction is separated and flows out through a pipe.

When the hot vapours rise up the column, the vapours cool.

Most of the compounds in the crude oil evaporate.

(ii) The naphtha fraction is cracked to produce ethene (C2H

4).

Ethene is used to make the polymer called poly(ethene).

Name two substances produced when poly(ethene) burns in air.

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(b) In this question you will be assessed on using good English, organising information clearlyand using specialist terms where appropriate.

Each year in the UK, billions of plastic bags are given free to shoppers. These bags aremade from poly(ethene) and are often used only once. After being used many of these plastic bags are either thrown away as litter or buried inlandfill sites.

In 2006 over 10 billion of these plastic bags were given free to shoppers. In 2009 the number of plastic bags given to shoppers had decreased to 6 .1 billion. One reason for the decrease was because some supermarkets made people pay for theirplastic bags.

From 2011 a new type of plastic shopping bag made mainly from poly(ethene) had a use-by date of only one year printed on the bag.

Use the information above and your knowledge and understanding to describe advantagesand disadvantages of using plastic shopping bags made from poly(ethene).

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(Total 10 marks)

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Q10. The diagram shows a reaction which takes place in an oil refinery.

(a) X, Y and Z are all examples of which type of compound?

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(b) What type of chemical reaction takes place when compound X is converted intocompounds Y and Z?

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(c) Compounds Y and Z are both useful substances.

Compound Y is unsaturated. Compound Z is saturated.

(i) Suggest one use for compound Y.

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(ii) Suggest one use for compound Z.

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(Total 4 marks)

Q11. Known crude oil reserves are being used up rapidly. Crude oil is used to produce manyuseful fuels, such as petrol. One way to conserve crude oil reserves would be to increase theproduction of bio-fuels.

(a) Ethanol can be produced for use as a bio-fuel. Cars can be powered by ethanol orethanol–petrol mixtures.

Sugar cane can be fermented to give a mixture of water (boiling point 100 °C) and ethanol

(boiling point 78 °C).

(i) How can ethanol be separated from water?

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(ii) Ethanol, C2H

5OH, burns to release heat energy.

Complete the balanced symbol equation by writing in the formulae of the twoproducts.

C2H

5OH + 3O

2 2......... + 3.........

(2)

(b) The cost of producing a bio-fuel, such as ethanol, by fermentation, is at least three timeshigher than the production cost of petrol. It costs less to produce ethanol from alkanes. Inthe production, the vapour of an alkane is passed over a hot catalyst.

Ethene is then converted into ethanol.

(i) What has happened to the hexane to produce ethene?

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(1)

(ii) Complete the structural formula for ethene, C2H

4.

C C (1)

(iii) Name the compound that is added to ethene to produce ethanol, C2H

5OH.

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(c) As explained in parts (a) and (b), ethanol can be made using either sugar or alkanes as thestarting material.

Evaluate the advantages and disadvantages of using these two starting materials toproduce ethanol.

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(Total 10 marks)

Q12. Petrol sold in most countries now contains at least 5% ethanol. The production of ethanol, for use as a fuel, is being increased.

The flow diagram shows how ethanol can be produced from crude oil.

(a) Why does crude oil need to be fractionally distilled?

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(b) Hydrocarbons, such as decane, in the naphtha fraction are cracked to produce ethene. The balanced chemical equation shows the cracking of decane.

(i) Describe how cracking is done.

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C10

H22 →

decane

C8H

18 +

octane

C2H

4

ethene

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(ii) Complete the structural formula of ethene by drawing lines to represent eachcovalent bond.

(1)

H H

C C

H H

(c) The flow diagram below shows how ethanol, for use as a fuel, can also be produced fromfood crops.

Use the information in the two flow diagrams and your own knowledge and understanding toevaluate whether more of this ethanol should be produced from food crops or from crude oil.

Remember to give a conclusion to your evaluation.

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(Total 9 marks)

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Q13. This question is about the use hydrocarbons and the production of compounds fromhydrocarbons.

(a) The equation shows a reaction involving hydrocarbons.

C8H

18 → C

2H

4 + C

6H

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Hydrocarbon J Hydrocarbon K Hydrocarbon L

Choose the correct processes from the box to complete the sentences.

combustion hydration thermal decomposition polymerisation

(i) Hydrocarbons K and L are produced by ........................................... . (1)

(ii) Ethanol can be produced from hydrocarbon K by .............................. . (1)

(iii) Describe a test to distinguish between hydrocarbons K and L and give the result of

the test.

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(b) Hydrocarbon J burns completely in oxygen to produce carbon dioxide and water vapour.

2 C8H18 + 25 O2→

16 CO2 + 18 H2O

(i) When 114g of hydrocarbon J burns completely in 400g of oxygen it produces162g of water vapour.

What mass of carbon dioxide would be produced from burning 114g ofhydrocarbon J?

Show clearly how you work out your answer

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Answer = ................................. g (2)

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(ii) The mass of carbon dioxide produced is greater than the 114g of hydrocarbon Jthat was burned. Explain why.

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(c) Two different processes are used to produce ethanol.

Process 1 Process 2

Fermentation of a sugar solution byyeast in a reaction vessel.

The reaction vessel has to be emptied,cleaned and refilled every few days.

The process produces a 15% ethanolsolution in water.

Reaction of ethene (from crude oil) withsteam in a reactor.

The reaction is only stopped if there is afault in the reactor.

The process produces 100% ethanol.

(i) Give one advantage that Process 1 has over Process 2.

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(ii) What advantages to a manufacturer of ethanol, does Process 2 have overProcess 1?

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(Total 11 marks)

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Q14. The equation below shows the cracking of a hydrocarbon compound into two differentcompounds, A and B.

(a) State two differences between the structures of compounds A and B.

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(b) Why is compound A useful in industry?

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(Total 3 marks)

Q15. Poly(ethene) is a long-chain saturated hydrocarbon. The formula for part of the polymer

chain is:

(a) Write the structural formula of the small molecule from which poly(ethene) is made.

(2)

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(b) Saturated hydrocarbons, such as propane, are fuels.

Write a balanced equation for the complete combustion of propane, C3H

8.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . + . . . . . . . . . . . . . . . . . . . . . . . . . . . . → . . . . . . . . . . . . . . . . . . . . . . . . . . . . + . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (3)

(Total 5 marks)

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M1. (a) oxygen

must be name

do not accept oxide or dioxide 1

(b) (i) 2 x C–C

and

5 x C –H

all single (line) bonds 1

(ii) C3 H

8

must be formula

do not accept lower case h 1

(iii) water 1

(c) ethane and butane boil at temperatures less than 20°C 1

ethene and hexene each have a carbon-carbon double bond 1

[6]

M2. (a) (i) exothermic

accept combustionallow burning or oxidation or

redox1

(ii) carbon monoxide / CO (is produced)

allow monoxide (is produced) ignore carbon oxide 1

because there is incomplete / partial combustion (of the fuel)

accept because there is insufficient oxygen / air (to burn the fuel) 1

(b) Marks awarded for this answer will be determined by the Quality of WrittenCommunication (QWC) as well as the standard of the scientific response.Examiners should also refer to the information in the Marking guidance.

0 marks No relevant content.

Level 1 (1-2 marks) There is a statement that crude oil is heated or that substances are cooled.However there is little detail and any description may be confused or inaccurate.

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Level 2 (3-4 marks) There is some description of heating / evaporating crude oil and either fractionshave different boiling points or there is an indication of a temperature difference inthe column.

Level 3 (5-6 marks) There is a reasonable explanation of how petrol is or fractions are separated fromcrude oil using evaporating and condensing.

If cracking is given as a preliminary or subsequent process to fractional distillationthen ignore.

However, if cracking / catalyst is given as part of the process, maximum is level 2.

Examples of chemistry points made in the response could include:

• Some / most of the hydrocarbons (or petrol) evaporate / form vapours orgases

• When some of / a fraction of the hydrocarbons (or petrol) cool to theirboiling point they condense

• Hydrocarbons (or petrol) that have (relatively) low boiling points and arecollected near the top of the fractionating column or hydrocarbons with

(relatively) high boiling points are collected near the bottom of the fractionatingcolumn

• The process is fractional distillation

• Heat the crude oil / mixture of hydrocarbons or crude oil / mixture is heated toabout 350°C

• Some of the hydrocarbons remain as liquids

• Liquids flow to the bottom of the fractionating column

• Vapours / gases rise up the fractionating column

• Vapours / gases cool as they rise up the fractionating column

• The condensed fraction (or petrol) separates from the vapours / gases andflows out through a pipe

• Some of the hydrocarbons remain as vapours / gases

• Some vapours / gases rise out of the top of the fractionating column

• There is a temperature gradient in the fractionating column or the fractionating

column is cool at the top and hot at the bottom 6

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M3. (a) heat to vaporise (the crude oil)

do not accept cracking / burning1

vapours condense 1

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at different temperatures

allow they have different boiling points 1

(b) (alkanes) are hydrocarbons or are compounds of hydrogen and carbon only 1

alkanes are saturated or have only (carbon-carbon) single bonds

accept have no (carbon- carbon) double bonds accept general formula is C

n H

2n+2 for 2 marks

1

(c) Marks awarded for this answer will be determined by the Quality of WrittenCommunication (QWC) as well as the standard of the scientific response.


Level 1 (1-2 marks) There is a basic description of at least one advantage or one disadvantage of

extracting petroleum products from oil sands.

Level 2 (3-4 marks) There is a clear description of an advantage and a disadvantage of extractingpetroleum products from oil sands.

Level 3 (5-6 marks) There is a detailed description of both advantages and disadvantages of extractingpetroleum products from oil sands.

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Examples of the chemistry/environmental/economic/social points made in theresponse

Advantages:

• the oil sands are needed because crude oil is running out

• this crude oil is needed because demand is increasing

• the oil sands contain a large amount of crude oil

• the oil sands could improve Canada’s economy

• the oil sands provide employment for a lot of people

• the trees / forest are used for wood products / fuel

Disadvantages:

• destruction of environment / habitats

• fewer trees / forests to absorb carbon dioxide

• specified pollution, for example, visual, noise, atmospheric (including dust),water (including river or drinking) with cause, e.g. gases / particulates fromburning diesel

• large amounts of methane (natural gas) are used to provide energy

• energy / fuel needed for cracking and fractional distillation

• burning fuel releases carbon dioxide

• crude oil / natural gas contains locked up carbon

• crude oil is non-renewable 6

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M4. (a) (i) heat / evaporate the crude oil / change to gas or vapour

do not accept heat with catalyst 1

cool / condense (hydrocarbons)

allow small molecules at top and / or large molecules at bottom 1

at different temperatures / boiling points if the answer describes cracking ‘ no marks

1

(ii) C4H

10

1

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(b) H H H│ │ │

H ─C ─ C ─ C ─ H │ │ │ H H H

1

(c) (i) C5 to C

8 fraction are fuels or easier to burn or petrol (fraction)

accept C 21 to C 24 fraction not useful as fuels

do not accept produce more energy1

(ii) C2H

4

do not accept C 4 H

8

1

(iii) any three from:

• 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

do not accept price3

[10]

M5. (a) (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 1

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(b) any three from:

• replant trees / renewable / sustainable

ignore reusable

• carbon (dioxide) used by trees / photosynthesis

accept trees absorb carbon (dioxide) as they grow

ignore respiration

• it is a (continuous / carbon) cycle

accept burning wood is carbon neutral

or carbon (dioxide) goes back into the air

for the second and third bullet points: accept trees use carbondioxide which is released when (trees / wood are / is) burnt for 2 marks

• no new carbon (dioxide) is produced

or

no locked up carbon (dioxide) is released

or the carbon (dioxide) was absorbed millions of years ago

3

[4]

M6. (a) complete diagram with 2 carbon atoms and 5 hydrogen atoms each C–Cand each C –H linked by a single line (bond)

1

(b) (i) the greater the number of (carbon) atoms (in an alkane molecule) the greater its boiling point or vice versa

allow as the (carbon) chain gets longer the boiling point increases

ignore melting points

do not accept reference to greater number of molecules1

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(ii) they = hydrocarbons from the graph

it = C 30 H

62

any two from:

• low boiling point / volatile

accept they are gases or liquids

• low viscosity

• high flammability

accept easier to burn / ignite

• small molecules

accept short chains

ignore number of carbon atoms

• burn completely

ignore speed of burning 2

(c) (i) 16 (CO2) + 18 (H

2O)

1

(ii) (carbon dioxide in the Earth’s early) atmosphere

accept from volcanoes (millions of years ago)

or from dead plants / animals

allow dead sea creatures

ignore shells 1

(iii) increase in burning / use of fossil fuels 1

locked up carbon (carbon dioxide) is released

allow carbon / carbon dioxide from millions of years ago is released

accept extra carbon dioxide is not ‘ absorbed ’ (by the carbon cycle)1

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M7. any four from:

to gain 4 marks both pros and cons should be given

Arguments for biodiesel

max three from:

• sustainable / renewable

• (carbon neutral) absorbs CO2 when growing / during photosynthesis

• burning biodiesel produces low amounts particulates / carbon monoxide

allow burning biodiesel produces little / low amount of globaldimming

ignore sulfur dioxide

• 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 accept produced by a low tech process

• biodegrades (easily)

ignore engine effects

Arguments against biodiesel

max three from:

• creates food shortages

accept price of food increases

• deforestation to plant more crops leads to loss of habitat / biodiversity or deforestationleads to a reduction in absorption of CO

2

allow burning trees increases CO 2

allow deforestation increases global warming

• burning biodiesel produces high amounts of nitrogen oxides

allow increases acid rain

• crops takes time to grow

allow crops can fail

• vast areas of land needed to grow crops 4

conclusion supported by the argument presented, which must give added value to the points forand against given above

1

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M8. (a) both bars correct height (to better than half a square)

1 mark for both

both bars correctly labelled (w.r.t. relative heights if these incorrect)

for 1 mark2

(b) a lot less / much less / 18 times less (converse must specify coal)gains 1 mark

1

(c) ideas that

• at high temperatures (produced when fuels burn)

• nitrogen and oxygen from air / atmosphere combine / react or nitrogen from air / atmosphere oxidises

for 1 mark each2

(d) ideas that

• coal produces most carbon dioxide / more CO2 than gas / oil

• because coal is (mostly) carbon

• gas produces less carbon dioxide than coal / oil

• oil and gas also contain hydrogen / contain more hydrogen atoms than carbonatoms / also produce water

any three for 1 mark each3

(e) sulphur

for 1 mark2

[9]

M9. (a) (i) (1)

5

3

(6)

4

2

all numbers in the correct order gains both marks

any two numbers in the correct position gains 1 mark2

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(ii) Water

ignore formula if correct name given

accept hydrogen oxide

allow H 2 O

1

carbon dioxide

allow CO 2

accept carbon monoxide / CO or carbon / C1

(b) Marks awarded for this answer will be determined by the Quality of WrittenCommunication (QWC) as well as the standard of the scientific response.Examiners should also apply a � best-fit� approach to the marking.


Level 1 (1-2 marks) There is a basic description of at least one advantage or one disadvantagecaused by using plastic shopping bags made from poly(ethene)

Level 2 (3-4 marks) There is a clear description of both an advantage and a disadvantage, caused by using plastic shopping bags made from poly(ethene).

Level 3 (5-6 marks) There is a detailed description of both advantages and disadvantagescaused by using plastic shopping bags made from poly(ethene)

examples of the chemistry/social points made in the response: ignore cost unqualified

Advantages:

• Simple properties eg strong / low density / water resistant

• Bags can be reused (for shopping) or another specified use eg bin liners

• Money charged for bags can go to good causes or encourage reuse

• Poly(ethene) bags can be recycled eg made into milk bottle crates

• Poly(ethene) bags can be burned to provide heat for buildings/generation ofelectricity

• New bags are now made that can biodegrade

Disadvantages:

• (Older) bags can take many years to biodegrade

• There is a shortage of landfill space

• Bags are made from (crude) oil which is a non-renewable resource/running out

• Large amounts of energy/fuel are used for the production of poly(ethene)

• Production of poly(ethene) releases carbon dioxide/causes global warming

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• Specified issue caused by litter eg visual pollution or effect on wildlife

• Burning bags release carbon dioxide / causes global warming 6

[10]

M10. (a) hydrocarbon 1

(b) thermal decomposition / cracking1

(c) (i) making polymers / poly(e)thene

accept plastic (bags)1

(ii) fuel 1

[4]

M11. (a) (i) by (fractional) distillation

accept a description of the distillation process (heat and howseparation works) eg heat and condense accept boil / vapourise etc for heat

or

fractionation 1

(ii) CO2

note the order of these products must be correct1

H2O

wrong way round = 1 mark1

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(b) (i) (hexane) has been broken down (into smaller hydrocarbons / molecules) 1

accept (thermal) decomposition / cracked / split / broken up owtte

(ii) H H │ │ C = C │ │ H H

accept CH 2= CH

2

1

(iii) water / hydrogen oxide / steam

accept H 2 O

1

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(c) 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

not ‘ expensive ’ alone

• 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 alkanes:

• economic costs are low

• continuous process

• country has large oil resources

• country has oil refineries / cracking plants

• very pure product

• faster process4

[10]

M12. (a) it is a mixture (of hydrocarbons) or contains hydrocarbons with different boiling points

accept to separate (crude) oil (into fractions) or obtain the naphtha(fraction)

accept to get useful products

ignore removal of impurities 1

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(b) (i) heat / vaporise

mention of hydrogen = max 1

accept thermal (decomposition) for heat

allow boil

do not allow temperatures below 100°C

ignore steam1

catalyst

allow alumina / porous pot

ignore other catalysts1

(ii) 4 × C – H and C = C

ignore brackets with or without an ‘ n ’ before them

do not allow poly(ethene) 1

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(c) ignore ideas about carbon dioxide formation / photosynthesis or cost / economics / environmentally friendly

any four from:

candidates are only awarded 1 mark if they use equivalent pairs ofbulleted points

must be at least one advantage and one disadvantage for all four marks

cropsadvantages eg:

crude oil

disadvantages eg:

• renewable (resource) / sustainable

• non - renewable (resource) / finite / running out

• low / less energy / fuel needed for process or lower temperature [ignore heat orquoted temperatures]

• high / more energy needed for process or / higher temperature

• can use waste plant / crop material

• carbon neutral

• not carbon neutral or releases locked up carbon

• low safety risk (processes)

• high safety risk (process)

• low technology

• high technology

• risk of major oil spillage

• can be used to make other products

disadvantages eg:

advantages eg:

• batch process / process is slow

• continuous process / process is fast

• many steps in the process

• few steps in the process

• ethanol is impure / may contain water

• ethanol is pure

• food shortages

• ‘ conserves ’ food

• 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

• can accept reverse arguments

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4

a conclusionwith a reasoned argument based on valid advantages and disadvantages

there must be at least one advantage and one disadvantage,however, a matched pair, although only awarded one mark wouldallow the conclusion mark to be awarded

1

[9]

M13. (a) (i) thermal decomposition 1

(ii) hydration 1

(iii) add bromine (water)/iodine solution (to K and L) 1

K will decolourise these solutions or L will not decolourise these solutions

1

(b) (i) 352 (g)

for correct answer

if answer is incorrect 400 + 114 – 162 gains 1 mark2

(ii) because 2 molecules of hydrocarbon J had 25 molecules of oxygen added

or

because 2 molecules of hydrocarbon J produced 16 molecules of carbon dioxide

allow because oxygen has been added to hydrocarbon Jfor 1 mark

2

(c) (i) raw materials are renewable

accept does not use crude oil1

(ii) alcohol does not need to be distilled

accept alcohol produced is pure 1

process is continuous1

[11]

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##

(a) Compound A has fewer C atoms or Compound B has fewer H atoms

Compound A has C = C/double bond or Compound A is unsaturated

each for 1 mark(accept converse i.e compound B has not ...)

2

(b) Compound A is reactive or can be used to make many substancesor can be used in polymerisation/making plastics/named plastic or can be used as a fuel

any one for 1 mark1

[3]

M15. (a) C=C

do not accept C 2 H

4

1

four Hs only, two attached to each carbon

credit CH 2 CH

2 for two marks

1

(b) C3H

8 + 5O

2 → 3CO

2 + 4H

2O

two correct formulae LHS 1

can be in either order two correct formulae RHS

1

can be in either order

correctly balanced, consequential

marking allowed for 10 O 1

[5]

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Documents

Crude Oil and Fuels and Useful Substances From Crude Oil c1 Revision Higher