Q. Useful fuels can be produced from crude oil. Crude oil is a mixture of hydrocarbons. (a) The table shows the boiling points of four of these hydrocarbons. Hydrocarbon Boiling point in C methane, CH 4 6 butane, C 4 H 0 0 pentane, C 5 H +36 decane, C 0 H +75 Tick ( ) two statements that are correct about these hydrocarbons. Statement Tick ( ) decane has the largest molecules pentane is a liquid at 40 C methane and butane are gases at 0 C methane has the highest boiling point butane does not boil () (b) Natural gas supplied to homes and schools is mainly methane. The diagram shows an apparatus to investigate the two substances produced when natural gas burns completely in air. (i) Name the liquid that collects in the U-tube... (ii) Name the gas that turns the limewater cloudy... () () Page of 34
(c) There are two substances produced when natural gas burns with the air hole open. The diagram shows the Bunsen burner flame when natural gas burns with the airhole closed. Partial combustion takes place. Name one other substance that could be produced when natural gas burns with the air hole closed.... () (d) Some crude oil contains sulfur. Petrol and diesel fuels are produced from crude oil. The sulfur must be removed from these fuels before they are burned. Explain why............. () (Total 7 marks) Q. Crude oil is a complex mixture of hydrocarbons, mainly alkanes. The number of carbon atoms in the molecules ranges from to over 00. (a) How does the boiling point change as the number of carbon atoms in the molecules increases?.. () (b) Name the method used to separate petroleum into fractions.. () Page of 34
(c) The simplest hydrocarbon is methane, CH 4. Its structure can be represented: Draw the structure of ethane, C H 6. () (Total 3 marks) Q3. Crude oil is a mixture of many saturated hydrocarbons. They can be separated into fractions by the process of fractional distillation. State what is meant by: (i) hydrocarbon.... () (ii) saturated.... () (iii) fraction.... () (Total 4 marks) Q4. (a) Burning fuels changes the Earth s atmosphere. The new substances produced are mainly gases. The following is a list of types of reaction. combustion cracking electrolysis fermentation neutralisation reduction Choose, from the list, the word which has the same meaning as burning.. () Page 3 of 34
(b) The table shows the gases formed when four fuels, A to D, are completely burned in air. FUEL GAS FORMED ON BURNING CARBON DIOXIDE CO WATER VAPOUR H O SULPHUR DIOXIDE SO A B C D Which fuel, A to D, is hydrogen, H?... () (Total marks) Q5. Crude oil is a resource from which fuels can be separated. (a) The name of the main fuel fractions and one of the hydrocarbons in each fraction are shown in the table. (i) How does the number of carbon atoms in a hydrocarbon affect its boiling point? () Page 4 of 34
(ii) Suggest the lowest temperature to which crude oil needs to be heated to vaporize all the hydrocarbons in the table. Temperature =... C () (iii) Dodecane boils at 6 C. At what temperature will dodecane gas condense to liquid? Temperature =... C () (b) The bar chart shows the relative supply and demand for the petrol and diesel fractions. (i) How does the relative supply and demand for petrol and diesel fractions cause problems for an oil company? () (ii) Suggest one way an oil company could solve these problems. () (Total 6 marks) Q6. Crude oil is a mixture of mostly alkanes. (a) Crude oil is separated into useful fractions by fractional distillation. Page 5 of 34
Draw the structural formula of propane, C 3 H 8 () (i) Describe and explain how the mixture of alkanes is separated by fractional distillation...................... (3) (ii) The table gives the name and formula for each of the first three alkanes. Complete the table to show the formula of butane. Name of alkane Formula Methane CH 4 Ethane C H 6 Propane C 3 H 8 Butane () (b) The structural formula of methane, CH 4, is: H H C H H Page 6 of 34
(c) The relative amounts of and the market demand for some hydrocarbons from the fractional distillation of crude oil are shown in the graph. (i) Why is the market demand for the C 5 C 8 fraction higher than the market demand for the C C 4 fraction?...... () (ii) Cracking is used to break down large hydrocarbon molecules into smaller hydrocarbon molecules. Complete the symbol equation by writing in the formula of the other hydrocarbon. C 0 H 4 C 6 H 34 +... () Page 7 of 34
(iii) The C 5 C 8 fraction has low supply and high market demand. Suggest three ways in which the oil industry could overcome this problem........... 3...... (3) (Total 0 marks) Q7. Crude oil is a natural resource from which useful fuels can be separated. (a) Crude oil is a mixture of hydrocarbons. Complete the sentence about a hydrocarbon molecule. A hydrocarbon molecule is made up of... and carbon atoms only. () (b) Many fuels come from crude oil. Some of these fuels are shown in the diagram. Suggest two properties of these fuels that allow them to be separated from crude oil. () Page 8 of 34
(c) Fuels from crude oil burn to provide heat energy. When a fuel burns, it combines with oxygen in the air and produces carbon dioxide and water. When there is not enough oxygen, the fuel burns and also produces carbon monoxide and carbon particles. Draw a straight line from each substance that links it to a possible environmental problem. One has been done for you. (3) (Total 6 marks) Q8. The hydrocarbons in crude oil can be separated into useful fractions. Fraction Boiling point in C Carbon chain length Relative % in crude oil Relative % demand Naphtha 0 80 5 9 0 0 Gasoline (petrol) 0 00 5 0 0 0 Kerosene (paraffin) 80 60 0 6 5 3 Diesel 60 340 4 0 0 5 Fuel oil 370 600 0 70 45 (a) Why does gasoline (petrol) have a lower boiling point than fuel oil? () Page 9 of 34
(b) Suggest why gasoline (petrol) costs more than fuel oil. () (c) Describe how fuel oil can be changed into gasoline (petrol). () (Total 5 marks) Q9. Hot air balloons burn hydrocarbons to heat the air. (a) The hot air contains these gases: nitrogen, N oxygen, O argon, Ar carbon dioxide, CO water vapour, H O (i) Argon is an element. What is an element? () Page 0 of 34
(ii) Name one other gas in the hot air that is also an element. () (b) Propane, C 3 H 8, can be represented as: H H H H C C H H H C H Use the correct words from the box to complete the sentences. bond carbon compound element mixture (i) Propane is a... and is made up of atoms of hydrogen and... () (ii) Each line between the atoms in propane represents a chemical... () (Total 5 marks) Q0. Most electricity in the UK is generated in power stations that burn fossil fuels. The diagram lists some of the substances released into the air when fossil fuels are burned. (a) (i) Which one of the substances released into the air causes acid rain?... () Page of 34
(ii) In the sentence below, draw a ring around the correct answer. The type of environmental pollution caused by smoke particle is global dimming global warming rising sea levels () (iii) Suggest how the burning of fossil fuels may cause climate change............. () Page of 34
(b) The table shows the percentage of electricity generated by different energy sources. Energy sources Percentage (%) Renewables Nuclear Coal Gas and Oil 8 0 3 40 Complete the bar chart to show the percentage of electricity generated by coal and by gas and oil. () (Total 6 marks) Page 3 of 34
Q. A large reservoir is surrounded by trees. Planners need to protect the environment. The distance around the reservoir is many kilometres. There will be only one road access to a car park a few kilometres from the reservoir. From the car park people would be transported to accommodation, activities or places of interest by steam train. (a) Coal contains carbon and small amounts of sulfur. The steam train would cause environmental problems if coal were used as the fuel. Explain why. (4) Page 4 of 34
(b) The planners have stated that, as a result of using the steam train, there must be no overall increase of carbon dioxide added to the atmosphere. The steam train would be considered as carbon neutral if wood, from the surrounding forest, were used as the fuel. Suggest why. (3) (Total 7 marks) Q. 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. (3) Page 5 of 34
(b) The second bar-chart shows how much sulphur dioxide is produced by burning the same three fuels. Compare the amount of sulphur produced by burning gas with the amount produced by burning coal... () (c) (i) Coal and oil produce carbon dioxide and sulphur dioxide when they burn. What elements must they contain? () (ii) Burning fuels also produce nitrogen oxides, even though the fuels contain no nitrogen. Explain why this happens. () (Total 9 marks) Q3. Hot air balloons are used mainly for pleasure trips. Page 6 of 34
(a) Air is a mixture of gases. Complete the table. (Carbon dioxide has been done for you.) Gas Chemical formula % in air nitrogen 78 oxygen O argon 0.9 carbon dioxide CO 0.03 (3) (b) The air in the balloon is heated using a propane burner. Propane, C 3 H 8, is a hydrocarbon that burns in air forming carbon dioxide, CO, and water, H O. (i) What does hydrocarbon mean? () (ii) Which gas, in the air, reacts with propane when it burns? () (iii) What type of chemical reaction happens when a hydrocarbon burns? () (iv) The formation of more carbon dioxide causes global problems. Explain why. () (Total 8 marks) Page 7 of 34
Q4. Since 000 there has been a lot more research into alternative, environmentally-friendly fuels for road transport. Several pollutants are found in the exhaust emissions produced when fossil fuels are used for road transport. Carbon monoxide (CO) interferes with the way that red blood cells carry oxygen. Carbon dioxide (CO ) increases the level of carbon dioxide in the atmosphere and causes global warming. Oxides of nitrogen (NO x ) are produced at high temperatures when nitrogen and oxygen from the atmosphere combine. Sulfur dioxide (SO ) is produced when sulfur impurities in the fuel combine with oxygen in the atmosphere. Tiny particles of solids are produced when the fuel does not burn completely. This increases the level of particulates (PM0) in the atmosphere. (a) Name the environmental effect caused by: (i) oxides of nitrogen (NO x ) and sulfur dioxide (SO )... () (ii) the increased level of particulates (PM0).... () (b) Diesel obtained from crude oil is often called fossil diesel. Biodiesel can be made from many vegetable oils. One research project compared the exhaust emissions when fossil diesel or biodiesel were used as fuels. Some of the relative amounts of these exhaust emissions are shown in the bar chart. Page 8 of 34
(i) Use your knowledge and the information above to explain the environmental benefits of using biodiesel as a sustainable, low pollution fuel. (3) (ii) 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 and the information above to explain why biodiesel s contribution to global warming is considered to be much less than that of fossil diesel. (3) (Total 8 marks) Q5. Known crude oil reserves are being used up rapidly. Crude oil is used to produce many useful fuels, such as petrol. One way to conserve crude oil reserves would be to increase the production of bio-fuels. (a) Ethanol can be produced for use as a bio-fuel. Cars can be powered by ethanol or ethanol petrol mixtures. Sugar cane can be fermented to give a mixture of water (boiling point 00 C) and ethanol (boiling point 78 C). (i) How can ethanol be separated from water?...... () Page 9 of 34
(ii) Ethanol, C H 5 OH, burns to release heat energy. Complete the balanced symbol equation by writing in the formulae of the two products. C H 5 OH + 3O... + 3... () (b) The cost of producing a bio-fuel, such as ethanol, by fermentation, is at least three times higher than the production cost of petrol. It costs less to produce ethanol from alkanes. In the 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?... () (ii) Complete the structural formula for ethene, C H 4. C C () (iii) Name the compound that is added to ethene to produce ethanol, C H 5 OH.... () Page 0 of 34
(c) As explained in parts (a) and (b), ethanol can be made using either sugar or alkanes as the starting material. Evaluate the advantages and disadvantages of using these two starting materials to produce ethanol. (4) (Total 0 marks) Page of 34
M. (a) decane has the largest molecules methane and butane are gases at 0 C (b) (i) water (ii) carbon dioxide (c) carbon (soot particles) accept carbon monoxide (d) burns to produce sulfur dioxide (sulfur dioxide) causes acid rain [7] M. (a) the more C atoms the higher the b.pt./temperature Allow just higher. Not answer based on melting point for mark (b) (fractional) distillation/fractionation for mark (c) must include H atoms and lines not CH 3 CH 3 for mark [3] Page of 34
M3. (i) carbon and hydrogen only or compound of for mark each (ii) single bonds only or no double bonds etc or contains maximum number of hydrogen atoms for mark (iii) molecules of similar chain length similar boiling points limited range of boiling points etc any for mark [4] M4. (a) combustion for one mark (b) B for one mark [] M5. (a) (i) the greater the number (of carbon atoms), the higher its boiling point do not accept hydrocarbons for carbon atoms allow converse allow melting point (ii) accept answers in the range 344 to 350 (iii) 6 Page 3 of 34
(b) (i) EITHER shortage of petrol or demand for petrol is higher than supply diesel is in excess or supply of diesel is higher than demand OR petrol low supply and diesel high supply () petrol high demand and diesel low demand () petrol / diesel not specified = max (ii) any one from: use diesel to make petrol accept crack diesel or description of cracking make diesel cheap(er) (than petrol) or make petrol more expensive accept lobby the government to reduce the tax on diesel / increase tax on petrol mix ethanol with petrol ignore biodiesel [6] M6. (a) (i) heat / evaporate the crude oil / change to gas or vapour do not accept heat with catalyst cool / condense (hydrocarbons) allow small molecules at top and / or large molecules at bottom at different temperatures / boiling points if the answer describes cracking no marks (ii) C 4 H 0 (b) H H H H C C C H H H H Page 4 of 34
(c) (i) C 5 to C 8 fraction are fuels or easier to burn or petrol (fraction) accept C to C 4 fraction not useful as fuels do not accept produce more energy (ii) C H 4 do not accept C 4 H 8 (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 price 3 [0] M7. (a) hydrogen ignore formulae (b) any two from: different sized molecules / more or less (carbon) atoms (in molecules) ignore different densities fuels have different boiling points fuels condense at different temperatures Page 5 of 34
(c) all three correct = 3 marks two correct = marks one correct = mark 3 [6] M8. (a) any one from: gasoline / petrol / it contains short(er) chains / hydrocarbons or small(er) molecules or contains few(er) carbons accept fuel oil contains long(er) chain length / large(r) molecules or contains many carbons ignore particles gasoline / petrol / it has weak(er) / small(er) intermolecular forces accept fuel oil has strong(er) / great(er) intermolecular forces Page 6 of 34
(b) only accept figures if used in a comparative statement any two from: gasoline / petrol / it is in high demand accept fuel oil is in low demand gasoline / petrol / it is in short supply accept fuel oil is plentiful accept answers such as gasoline / petrol / its supply is less than demand for marks or gasoline / petrol / its percentage in crude oil is less than demand for marks (high) tax / duty cracking costs in terms of money / energy accept cracking expensive (c) any two from: ignore particles (fuel oil / it) heated / vaporised with catalyst accept a named catalyst if first two bullet points are not awarded cracking gains mark (to give / form / produce) short(er) chains / hydrocarbons or small(er) molecules or contains few(er) carbons if wrong process named max mark [5] M9. (a) (i) made up of one sort of atom accept it is in the periodic table or has its own symbol (ii) nitrogen / N / N or oxygen / O / O do not accept argon or helium do not accept oxide Page 7 of 34
(b) (i) compound carbon (ii) bond [5] M0. (a) (i) sulfur dioxide / SO (ii) global dimming (iii) carbon dioxide / CO ignore ozone increases the levels (of carbon dioxide) accept it is a greenhouse gas or causes global warming / greenhouse effect (b) gas / oil bar correct length coal bar correct length [6] Page 8 of 34
M. (a) any two environmental problems with linked explanations global warming () accept effects of global warming caused by (formation of) carbon dioxide / greenhouse gas () ignore greenhouse effect acid rain () accept effects of acid rain ignore respiratory problems caused by ( formation of) sulfur dioxide () accept sulfur oxide ignore sulfuric acid global dimming () ignore respiratory problems caused by ( formation of) particles / particulates / fires / smoke / carbon / pm 0 () scarring of landscape () caused by mining / quarrying of coal () ignore ozone layer max 4 (b) any three from: replant the trees / renewable / sustainable ignore reusable carbon dioxide is used by the trees / photosynthesis accept trees absorb carbon dioxide as they grow do not allow respiration it s a (continuous carbon) cycle accept carbon dioxide goes back into the air accept trees use CO which is released when trees are burnt no new carbon (dioxide) is produced or no locked up carbon (dioxide) is released accept no carbon (dioxide) from fossil fuels is produced 3 [7] M. (a) each bar correct height ( bars) to less than ½ square mark for each both bars correctly labelled (in relation to size of bars) for mark 3 Page 9 of 34
(b) less gains mark but a lot less / much less / 8 times less or more if referring to coal gains marks (c) (i) carbon sulphur for mark each (ii) ideas that at high temperatures, (produced when fuels burn) nitrogen and oxygen from atmosphere combine / react for mark each [9] M3. (a) N 0 % Ar accept an answer in this range (b) (i) compound of carbon and hydrogen only do not accept mixture (ii) Oxygen or O (iii) (iv) exothermic accept combustion or oxidation increases greenhouse effect global warming or example [8] Page 30 of 34
M4. (a) (i) acid rain accept consequences of acid rain allow asthma / bronchitis ignore toxic gas (ii) global dimming accept dimming alone (b) (i) sustainable: maximum two from: crops (that produce oil) can be grown in most places owtte renewable use less fossil fuels / diesel use (refined) waste oils low pollution: maximum two from: ignore references to CO here most emissions are lower or any two named emissions from CO / SO / PM 0 are lower much / lot less SO emissions (than the others) owtte accept spillages / waste is biodegradable (ii) less new CO or (more) carbon neutral plants / photosynthesis use carbon (dioxide) from the air* it / biodiesel releases carbon (dioxide) from plants / crops / photosynthesis* (*) allow mark for biodiesel is (more) carbon neutral 3 (fossil) diesel releases locked up / new carbon (dioxide) / doesn t absorb CO / absorbed it millions of years ago [8] Page 3 of 34
M5. (a) (i) by (fractional) distillation or accept a description of the distillation process (heat and how separation works) eg heat and condense accept boil / vapourise etc for heat fractionation (ii) CO note the order of these products must be correct H O wrong way round = mark (b) (i) (hexane) has been broken down (into smaller hydrocarbons / molecules) accept (thermal) decomposition / cracked / split / broken up owtte CH (ii) H H C = C H H accept CH = (iii) water / hydrogen oxide / steam accept H O Page 3 of 34
(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 CO / 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 process 4 [0] Page 33 of 34
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