Q1 This question is about hydrocarbons.

Transcription

1 Q This question is about hydrocarbons. (a) The names and formulae of three hydrocarbons in the same homologous series are: Ethane C 2 H 6 Propane C 3 H 8 Butane C 4 H 0 The next member in the series is pentane. What is the formula of pentane?... () Which homologous series contains ethane, propane and butane? Tick one box. Alcohols Alkanes Alkenes Carboxylic acids () (c) Propane (C 3 H 8 ) is used as a fuel. Complete the equation for the complete combustion of propane. C 3 H 8 + 5O (2) (d) Octane (C 8 H 8 ) is a hydrocarbon found in petrol.

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3 Q2 Crude oil is a fossil fuel. (a) To make crude oil more useful it is separated into fractions. Use the correct word from the box to complete each sentence. boiling compound decomposition filtration mixture molecule distillation (i) Crude oil is a... of different substances. The substances in crude oil have different... points. () () (iii) Crude oil is separated by fractional.... () Petrol is one of the fractions produced from crude oil. Car engines use a mixture of petrol and air. The diagram shows some of the gases produced. (i) What type of reaction happens to petrol in a car engine? () Petrol contains octane (C 8 H 8 ). Complete the word equation for the reaction of octane with oxygen. octane (2) (Total 2 marks)

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5 Q3(c) Some fractions from crude oil contain large hydrocarbon molecules. These molecules can be cracked to produce smaller, more useful molecules. An equation for cracking decane is: C 0 H 22 C 3 H 8 + C 2 H 4 + C 5 H 0 decane propane ethene pentene (i) Why is propane useful?() Draw bonds to complete the displayed structure of ethene. () (iii) What is the colour change when bromine water reacts with ethene? () (iv) Complete the sentence. Pentene is useful because many pentene molecules can join together to form.... ()

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7 Q4 Alkanes are hydrocarbons found in crude oil. (a) (i) Complete the sentence. Hydrocarbons contain the elements... and... only. () Ethane is an alkane with the formula C 2 H 6 Draw a ring around the correct answer to complete the sentence. C n H n Alkanes are hydrocarbons with the general formula C n H 2n C n H 2n+2 () Crude oil is separated into useful fractions by fractional distillation. Describe and explain how crude oil is separated into fractions by fractional distillation. Use the diagram to help you answer the question (4) (c) Dodecane (C 2 H 26 ) from crude oil is cracked to produce ethene (C 2 H 4 ). (i) Complete the equation for this reaction. C 2 H 26 2 C 2 H () Give two conditions needed for cracking (2)

8 M4a) (i) hydrogen / H and carbon / C answers can be in either order if letters given, must be capital H C nh 2n+2 (most) crude oil vaporises / evaporates or crude oil enters as a vapour (vapour) cools as it rises up the tower / column or tower / column cooler at the top or negative temperature gradient the fractions have different boiling / condensation points / ranges accept the larger the molecules, the higher the boiling point / condensation point so they will condense at different levels in the tower allow will collect at different levels if condensation mentioned allow will condense to give different fractions if no other mark is gained allow mark for mention of heating (c) (i) C 8H 8 if one answer is given C 8H 8 is the only acceptable answer credit any correct combination of alkanes and alkenes, eg C 5H 2 and C 3H 6 hot / high temperature accept any temperature in the range C heat is insufficient catalyst accept a named catalyst alumina or zeolites or aluminosilicates or broken pot ignore other named catalysts allow (mixing with) steam as an alternative to second marking point ignore pressure [9]

9 Q5This question is about organic compounds. (a) Ethanol burns in air. Use the correct answer from the box to complete the word equation for the reaction. ethanol +... carbon dioxide + water () Use the correct answer from the box to complete the sentence. Ethanoic acid is in.... () (c) Ethanoic acid is a carboxylic acid. Which diagram, A, B or C, has a ring around the functional group of a carboxylic acid? Write your answer in the box. () (d) Ethyl propanoate is produced by reacting ethanol with propanoic acid. What type of organic compound is ethyl propanoate? () (e) Organic compounds such as ethyl propanoate are used in perfumes. Give two properties of these compounds that make them suitable for use in perfumes (2) (Total 6 marks)

10 M5 (a) (c) (d) (e) oxygen allow correct answer shown in box if answer line blank vinegar C volatile Ester allow correct answer shown in box if answer line blank pleasant smell allow low boiling point / evaporates [6]

11 Q6 In this question you will be assessed on using good English, organising information clearly and 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 and the expected demand for petroleum products. Canada s oil sands hold about 20% of the world s known crude oil reserves. The oil sands contain between 0 to 5% 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. The trees are removed. Then large diggers and trucks remove 30 metres depth of soil and rock to reach the oil sands. The oil sands are quarried. Boiling water is mixed with the quarried oil sands to separate the bitumen from the sand. Methane (natural gas) is burned to heat the water. The mixture can be separated because bitumen floats on water and the sand sinks to the bottom of the water. The bitumen is cracked and the products are separated by fractional distillation. Use the information given and your knowledge and understanding to suggest the advantages and disadvantages of extracting petroleum products from oil sands

12 M6 Marks awarded for this answer will be determined by the Quality of Written Communication (QWC) as well as the standard of the scientific response. 0 marks No relevant content. Level (-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 extracting petroleum products from oil sands. Level 3 (5-6 marks) There is a detailed description of both advantages and disadvantages of extracting petroleum products from oil sands. Examples of the chemistry/environmental/economic/social points made in the response 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 from burning 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

13 Q7 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? ( Ethanol, C 2H 5OH, burns to release heat energy. Complete the balanced symbol equation by writing in the formulae of the two products. C 2H 5OH + 3O (2 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?... ( Complete the structural formula for ethene, C 2H 4. C C () (iii) Name the compound that is added to ethene to produce ethanol, C 2H 5OH.... () (c) As explained in parts (a) and, 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)

14 M7(a) (i) by (fractional) distillation accept a description of the distillation process (heat and how separation works) eg heat and condense accept boil / vapourise etc for heat or fractionation CO 2 note the order of these products must be correct H 2O wrong way round = mark (i) (hexane) has been broken down (into smaller hydrocarbons / molecules) accept (thermal) decomposition / cracked / split / broken up owtte H H C = C H H (iii) accept CH 2 = CH 2 water / hydrogen oxide / steam accept H 2O (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 2 / 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

15 Q8 The diagram shows an apparatus that can be used to carry out cracking reactions in a laboratory. (a) (c) (d) (e) (f) Why is aluminium oxide or broken porcelain used? Paraffin contains decane. The cracking of decane can be represented by the equation below. A decane molecule is split into two smaller molecules. Complete the equation by adding the formula of the other product. C 0 H 22 (l)... (l) + C 2 H 4 (g) decane Would you expect C 2 H 4 molecules to collect at position A or B shown on the diagram? Position... Explain your answer. Cracking reactions involve thermal decomposition. What is meant by thermal decomposition? Explain, as fully as you can, why cracking is used in the oil industry. To gain full marks in this question you should write your ideas in good English. Put them into a sensible order and use the correct scientific words. The cracking reaction produces a mixture of products. The mixture contains hydrocarbons with different boiling points. () () () (2) (3) Suggest a method of separating this mixture. () (Total 9 marks)

16 M8 (a) catalyst or speeds up the reaction (owtte) accept lowers activation energy not just helps reaction to take place ignore increased surface area C 8H 8 (c) (d) (e) allow H 8C 8 must be upper case do not accept powers B because it is a gas or because it has small molecules or because they are small position and reason for mark allow it has a lower / very low boiling point than A ignore references to solubility accept does not condense do not accept light molecules or bubbles into B do not accept it is small breakdown of a substance (owtte) do not accept decompose unqualified by the action of heat (owtte) Quality of written communication if the written communication makes sense and it is in context then award Q mark Q Q large to small molecules or scientific word that implies smaller, e.g. alkene / ethane / petrol any name or formula of alkane / alkene smaller than decane either advantages of smaller molecules or disadvantages of larger molecules e.g. hydrocarbons with large molecules are limited in their usefulness or converse for smaller molecules (f) large hydrocarbon molecules do not ignite easily / do not flow easily / are not very volatile or converse for smaller molecules more large hydrocarbon molecules are produced than are needed or converse for smaller molecules smaller molecules are useful as fuels alkenes / products can be used to make polymers (fractional) distillation accept fractionation accept good description do not accept just diagram

17 Q9 the label has been taken from a tube of Humbrol Polystyrene Cement, a glue used in model making. (a) The solvent used is,,-trichloroethane. The structural formula of this molecule is: (i) (iii) What do the lines between the atoms represent State whether,,-trichloroethane is saturated or unsaturated. Give one reason for your answer.,,-trichloroethane is being replaced in favour of a better solvent. Use information on the label to help you to suggest why. () () () Polystyrene is a plastic. Plastics are polymers which are made by the process of polymerisation. (i) What is meant by polymerisation? The table gives information about monomers and the polymers made from them. Complete the table. (2) (3) (Total 8 marks)

18 M9(a) (i) bonds / pair of electrons / shared electrons for one mark (iii) saturated since it has single bonds / no double bonds / no multiple bonds / maximum number of atoms attached for one mark sensible answer (e.g. it is harmful) or better solvent could be used on expanded polystyrene or foam for one mark (i) simply writing monomers form / react to form polymers gains no mark monomers join / bond / combine / link to form polymers = mark the mark is for the idea of joining to gain the second mark the idea of the relative size of monomer and polymer is required small molecules join to form a polymer (2 marks) many monomers join to form a polymer (2 marks) monomers join to form a large molecule / long chain (2 marks) many molecules join together (2 marks) for mark each 2 polyethene / poly(ethene) / polythene don t worry too much about the exact positioning of the C6H5 at the end of the bond placement of linking bonds inside / outside brackets is not important must have n for mark each [8]

19 Q0(a) This label has been taken from a bottle of vinegar. Vinegar is used for seasoning foods. It is a solution of ethanoic acid in water. The flow diagram shows some reactions of ethanoic acid. Give the name of: (i) gas A, alkali B, () () (iii) ester C () (iv) catalyst D () (v) carboxylic acid salt () (Total 5 marks)

20 M0i) A = hydrogen / H2 B = sodium hydroxide / NaOH or sodium oxide / Na2O (iii) C = ethyl ethanoate (acetate) / CH3COOC2H5 / CH3CO2C2H5 (iv) D = (concentrated) sulphuric acid / H2SO4 do not accept dilute sulphuric acid E = sodium ethanoate (acetate) / CH3COONa / CH3CO2Na

21 Q This question is about organic compounds. (a) Ethanol is an alcohol. One use of ethanol is in alcoholic drinks. Give two other uses of ethanol. (2) Which gas is produced when sodium reacts with ethanol? () (c) Ethanoic acid (CH 3 COOH) can be produced from ethanol (CH 3 CH 2 OH). (i) What type of reaction produces ethanoic acid from ethanol? Complete the displayed structure of ethanoic acid. () (iii) Solutions of ethanoic acid and hydrochloric acid with the same concentration have different ph values. Explain why the solution of ethanoic acid has a higher ph than the solution of hydrochloric acid. () (2) (d) Ethanol and ethanoic acid react in the presence of a catalyst to form an ester. (i) (iii) Name the ester made from ethanol and ethanoic acid. What type of chemical is used as a catalyst in this reaction? Esters are used in perfumes because they smell pleasant and are volatile. What does volatile mean? () () () (Total 0 marks Q

22 Ma) any two from: fuel allow source of energy solvent allow perfume / aftershave antiseptic allow antibacterial 2 Hydrogen (c) (i) oxidation do not allow redox (iii) correct structure ethanoic acid is a weak / weaker acid it = ethanoic acid because it does not completely ionise. allow because it does not completely dissociate (d) (i) ethyl ethanoate allow it has a lower concentration of hydrogen ions allow converse for hydrochloric acid do not allow ionising acid allow any strong acid allow correct formulae (iii) evaporates easily / quickly allow low boiling point do not allow flammable [0]

23 Q2 The figure below shows the displayed structures of five organic compounds, A, B, C, D and E. (a) Choose which organic compound, A, B, C, D or E, matches the descriptions. You may choose each compound once, more than once or not at all. Write the letter of the compound that: (i) (iii) (iv) is a saturated hydrocarbon comes from a homologous series with the general formula C n H 2n has the empirical formula C 2 H 6 O reacts with calcium carbonate to produce carbon dioxide () () () () (v) reacts with compound A to produce compound C. () Compound B (C 2 H 4 ) and C 8 H 8 are produced by cracking C 4 H 30 C 4 H 30 3C 2 H 4 + C 8 H 8 (i) Give two conditions for cracking. (2) Explain why C 8 H 8 has a lower boiling point than C 4 H 30 (2) (c) Compound B is a colourless gas. Give a chemical test and its result to show that compound B is unsaturated. Test... Result... (2) (d) Compound B is ethene. Complete the equation to show the formation of poly(ethene) from ethene. (3) (Total 4 marks)

24 M2 a) (i) D (iii) B A (iv) E (v) E (i) high temperature ignore hot / heat allow temperature quoted (range C) catalyst or steam C8H8 smaller molecule It = C8H8 therefore there are weaker intermolecular forces allow intermolecular bonds do not accept breaking covalent bonds / bonds or weaker intermolecular forces in C8H8 () allow intermolecular bonds so less energy to break () (c) add bromine water turns (from orange / yellow / red / brown) to colourless or decolourises do not accept discoloured ignore clear incorrect test = 0 marks (d) single C C bond four carbon-hydrogen bonds in place and two trailing bonds structure in brackets and n at bottom right [4]

25 Q3This question is about organic compounds. (a) Wine contains ethanol (CH 3 CH 2 OH). (i) Complete the displayed structure of ethanol. () Wine left in a glass for several days turns sour. The sour taste is caused by ethanoic acid. Complete the sentences. The ethanoic acid is produced from a reaction between ethanol and.... This type of reaction is.... (2) Propyl ethanoate, a fragrance, can be produced by reacting ethanoic acid with an alcohol. Propyl ethanoate is a member of a series of organic compounds. The members of the series all have the same functional group. The displayed structure of propyl ethanoate is: (i) (iii) Draw a ring around the functional group for this series on the displayed structure of propyl ethanoate. Name the series of organic compounds with this functional group.... The alcohol used to make propyl ethanoate has the formula CH 3 CH 2 CH 2 OH Name this alcohol. () ()... () (Total 6 marks)

26 M3 (a) (i) allow other arrangements provided connectivity is correct allow OH oxygen accept O 2 allow O oxidation allow oxidisation / oxidising / oxidised allow redox (i) ring around ester(s) do not allow ether(s) (iii) propanol propanol accept propan--ol allow propyl alcohol [6]

27 Q4. Ethene is used to produce poly(ethene). (a) Draw the bonds to complete the displayed formulae of ethene and poly(ethene) in the equation. (2) Polyesters are made by a different method of polymerisation. The equation for the reaction to produce a polyester can be represented as: Compare the polymerisation reaction used to produce poly(ethene) with the polymerisation reaction used to produce a polyester. (4) (Total 6 marks)

28 M4. (a) (ethene) (polyethene) any four from: poly(ethene) produced by addition polymerisation whereas polyester by condensation polymerisation poly(ethene) produced from one monomer wheareas polyester produced from two different monomers poly(ethene) produced from ethene / alkene whereas polyester from a (di)carboxylic acid and a diol / alcohol poly(ethene) is the only product formed whereas polyester water also produced poly(ethene) repeating unit is a hydrocarbon whereas polyester has an ester linkage 4 [6]

29 Q5This question is about polymers. (a) The polymer polyvinyl chloride (PVC) is non-biodegradable. Give one problem caused by non-biodegradable polymers. () Figure shows a short section of a PVC molecule. Figure PVC is produced from a monomer that contains two carbon atoms. Complete the structure of the monomer. C C (2) (c) Figure 2 represents a few short chains of PVC molecules. Explain why PVC softens and melts when heated. Use Figure 2 and your knowledge of structure and bonding to help you to answer the question. (3) (d) Monomer A and monomer B react to form polymer C. The displayed structures of monomer A, monomer B and a short section of polymer C are shown in Figure 3. The functional group of each structure is shown in a box. Complete the Table below below by writing the names of the functional groups for monomer A and polymer C. Name of functional group Table Monomer A... Monomer B alcohol Polymer C... (2)

30 M5(a) any one from: disposal or does not decompose (in landfill sites) or collection or sorting for recycling ignore non-biodegradable alone lack of space or more landfill sites other specified problems with waste (eg. litter or eyesore or harm to animals or destroys habitats) ignore pollution unqualified. if 2 marks not awarded, award mark for one of the following: a double bond between the two carbons and no additional trailing bonds two C atoms bonded together with three single bonds to hydrogen atoms and one single bond to a chlorine atom. no additional Cl or H. 2 (c) intermolecular forces or forces between the chains allow intermolecular bonds (intermolecular forces are) weak ignore references to no cross links between chains. allow mark for weak forces between layers. which are easily overcome (by heat) or need little energy to overcome or chains / molecules can slide over one another (when heated) if weak bonds or breaking covalent bonds mentioned only the third marking point is available. (d) Monomer A carboxylic acid do not allow carbolic Polymer C - ester (linkage) [8]