Alcohols — Paper 4 · IGCSE Sciences - Co-ordinated (Double) 0654

5 Petroleum is the raw material for the production of many useful substances. Fig. 5.1 shows processes A, B and C that can be used in the production of ethanol. petroleum process process process diesel ethene A B C other other ethanol materials materials Fig. 5.1 (a) Name the processes by drawing one line from each process to its name. process name catalytic addition A cracking B fermentation fractional distillation C polymerisation [2] (b) The formula of ethanol is C2H5OH. Explain why ethanol is not a hydrocarbon. … … [1] (c) Fig. 5.2 shows a camping stove which uses ethanol as the fuel. boiling water ethanol burner Fig. 5.2 Complete combustion of ethanol produces carbon dioxide and water. The balanced equation for this reaction is shown. C2H5OH + 3O2 2CO2 + 3H2O The stove uses 22 g of ethanol to boil 1 dm3 of water. (i) Complete steps 1 to 3 to calculate the maximum mass of carbon dioxide produced when boiling 1 dm3 of water. Show your working. [Mr : carbon dioxide, 44; ethanol, 46] Step 1 Calculate the number of moles in 22 g of ethanol. number of moles = … Step 2 Calculate the number of moles of carbon dioxide produced when 22 g of ethanol burns. number of moles = … Step 3 Calculate the mass of carbon dioxide produced when boiling 1 dm3 of water. mass = … g [3] (ii) A similar stove uses butane as the fuel. Butane produces less carbon dioxide when boiling 1 dm3 of water. Suggest whether using the butane stove or the ethanol stove causes less damage to the environment. Explain your answer. type of stove … explanation … … … [2] [Total: 8]

8 marks

Mark scheme: 5(a) 1 correct ; 3 correct ; 2 5(b) a hydrocarbon consists of only hydrogen and carbon ; 1 5(c)(i) Step 1: (22/46 =) 0.48 ; Step 2: (0.48 × 2 =) 0.96 ; Step 3: 0.96 × 44 = 42 (g) ; 3 5(c)(ii) (butane) least amount of greenhouse gas / carbon dioxide is a greenhouse gas; climate change / global warming / consequence of climate change ; 2 catalytic A cracking fermentation fractional polymerisation B C

This question in 0654/41 May/June 2019

2 Fig. 2.1 shows industrial processes carried out to make some useful materials from petroleum. petroleum process A other naphtha products process B other ethene products process C process D ethanol poly(ethene) Fig. 2.1 (a) Use words and phrases from the list below to name the processes A to D in Fig. 2.1. Each word or phrase may be used once, more than once or not at all. Process C has been named for you. addition polymerisation catalytic addition condensation polymerisation cracking dehydration electrolysis fractional distillation oxidation reduction process A … process B … catalytic addition process C … process D … [3] (b) In process A petroleum is separated into mixtures of hydrocarbons, such as naphtha. State the physical property of naphtha that enables it to be separated from the other hydrocarbon mixtures in process A. … [1] (c) In process B, larger molecules are changed into smaller molecules. The energy level diagram for this reaction is shown in Fig. 2.2. smaller molecules energy larger molecules progress of reaction Fig 2.2 State the type of chemical reaction that causes the type of energy change shown in Fig. 2.2. Explain your answer in terms of bond breaking and bond making. type of reaction … explanation … … … [3] (d) In process C ethene reacts with steam to produce ethanol, C2H5OH. A catalyst is used to increase the rate of reaction. State two other conditions necessary for this reaction. 1 … 2 … [2] (e) (i) In process D poly(ethene) is formed. The structure of poly(ethene) is shown. H H C C H H n (n is a large number) Describe the formation of poly(ethene) using the terms monomer and polymer. … … … … [2] (ii) Ethene is reactive and reacts with bromine. Poly(ethene) is less reactive and does not react with bromine. Explain this difference. … … [1] [Total: 12]

12 marks

Mark scheme: 2(a) A fractional distillation ; B cracking ; (C catalytic addition) D addition polymerisation ; 3 2(b) boiling point (range) ; 1 2(c) endothermic ; bond breaking takes in energy / is an endothermic process and bond formation gives out energy / is an exothermic process ; more energy taken in than given out ; 3 2(d) high temperature ; high pressure ; 2 2(e)(i) ethene is monomer ; many (monomers / molecules) join to make (long chain) polymer ; 2 2(e)(ii) poly(ethene) is not an alkene / does not have double bond / is saturated ; 1

This question in 0654/43 May/June 2019

11 Petroleum is separated into useful chemicals by fractional distillation. Fig. 11.1 shows a fractionating column. refinery gas gasoline naphtha diesel oil heated petroleum bitumen Fig. 11.1 (a) Table 11.1 shows the uses of some of the fractions. Complete Table 11.1. [3] Table 11.1 fraction use bitumen … diesel oil fuel in diesel engines naphtha feedstock for making chemicals gasoline … refinery gas … (b) Butane is a hydrocarbon found in refinery gas. (i) State two properties of butane gas. … … [2] (ii) Butane is a type of hydrocarbon called an alkane. Complete Fig. 11.2 to show the structure of a butane molecule. Show all of the atoms and all of the covalent bonds. H C H Fig. 11.2 [2] (iii) The alkanes are a homologous series. Describe what is meant by a homologous series. … … … [2] (c) Ethene, C2H4, is an alkene made by the cracking of large alkane molecules. Ethene reacts with steam to make ethanol, C2H5OH. C2H4 + H2O C2H5OH (i) State one other method of making ethanol. … [1] (ii) In an experiment 5.6 g of ethene reacts with excess steam. Calculate the maximum mass of ethanol that can be made. maximum mass of ethanol = … g [2] [Total: 12]

12 marks

Mark scheme: 11(a) bitumen – road surfaces ; gasoline – fuel in cars ; refinery gas – bottled gas for heating or cooking or camping ; 3 Question Answer Marks 11(b)(i) low boiling point colourless ignites easily unreactive any general property of a gas ;; max 2 11(b)(ii) 1 mark for structure with 4 carbon atoms ; 1 mark for the rest of the structure correctly drawn ; 2 11(b)(iii) (family of compounds with) same general formula ; similar chemical properties ; 2 11(c)(i) fermentation 1 11(c)(ii) relative molecular mass of C2H4 =28 and of C2H5OH = 46 or (46 × 5.6) ÷ 28 ; = 9.2 ; 2

This question in 0654/41 May/June 2020

8 Fig. 8.1 shows the structures of ethene and of ethanol. H H H H C C H C C O H H H H H ethene ethanol Fig. 8.1 (a) Ethene is an unsaturated hydrocarbon. Explain the meanings of the underlined words. unsaturated … … hydrocarbon … … [2] (b) Ethene has a simple molecular structure. Ethene does not dissolve in water. State one other physical property of substances with a simple molecular structure. … [1] (c) Ethanol is an alcohol made by fermentation. (i) Ethanol is used in alcoholic drinks. State another use for ethanol. … [1] (ii) Describe how ethanol is made by fermentation. … … … … … [4] [Total: 8]

8 marks

Mark scheme: 8(a) (ethene is unsaturated because) it contains a double bond between the carbon atoms ; (ethene is a hydrocarbon because) it contains carbon and hydrogen (atoms) only / AW ; 2 8(b) poor electrical conductor / low boiling point / evaporates easily / volatile ; 1 8(c)(i) solvent / fuel ; 1 8(c)(ii) fermentation requires water ; fermentation requires sugar / named sugar ; fermentation requires yeast / enzyme / zymase ; fermentation requires suitable temperature ; reference to anaerobic respiration ; max 4 4

This question in 0654/43 Oct/Nov 2020

11 Ethane and ethene are members of two different homologous series. Fig. 11.1 shows the structure of ethene. H H C C H H Fig. 11.1 (a) Draw the structure of ethane. [1] (b) Ethene is a member of the homologous series called the alkenes. The alkenes are all hydrocarbons. State two other features that the alkenes in the homologous series have in common. 1 … 2 … [2] (c) Ethene undergoes an addition reaction with steam. Fig. 11.2 shows the equation for the reaction. Complete the equation, by drawing the structure of the compound formed. H H H C C + O … H H H Fig. 11.2 [1] (d) Propene is another alkene. Fig. 11.3 shows the structure of propene. H H C C H H C H H Fig. 11.3 The polymer poly(propene) can be made from propene. Complete the structure of poly(propene) in Fig. 11.4. Include all the atoms and bonds of the repeating unit. H H C C Fig. 11.4 [2] (e) Poly(propene) is made from propene in an addition polymerisation reaction. Polyesters are a group of polymers made in a condensation polymerisation reaction. Describe the differences between addition polymerisation and condensation polymerisation. … … … … [2] [Total: 8]

8 marks

Mark scheme: 11(a) 1 ; 11(b) any two from: 2 same general formula / have formula C2H2 ; similar chemical properties ; contain (at least one) double bond ; 11(c) 1 ; 11(d) 2 mark for single bond between carbon atoms ; mark for rest of structure correct ; 11(e) addition polymerisation requires one monomer / condensation 2 polymerisation requires two monomers ; addition polymerisation produces a polymer only / condensation polymerisation produces a polymer molecule and a small molecule ;

This question in 0654/42 Oct/Nov 2022

2 (a) A student investigates two liquid fuels, A and B, to find out which fuel releases most energy. Fig. 2.1 shows the apparatus used. 1.5 g of each fuel is burned completely. thermometer copper can 100 g water spirit burner 1.5 g of liquid fuel Fig. 2.1 Table 2.1 shows the student’s results. Table 2.1 temperature of temperature of temperature fuel water at start water at end change / °C / °C / °C A 16 25 9 B 16 34 18 (i) Describe how the results show which fuel releases the most energy. … … [1] (ii) Fig. 2.2 is the equation representing the complete combustion of ethanol. H H O H O H C C O H + 3 2 C + 3 O O H H O H Fig. 2.2 This reaction is exothermic. Place a tick (3) in the box next to the correct explanation of an exothermic reaction. More energy is given out by bond breaking than is taken in by bond making. More energy is given out by bond making than is taken in by bond breaking. More bonds are broken than are made. More energy is taken in by bond breaking than is given out by bond making. [1] (b) Fig. 2.3 shows the energy level diagram for an exothermic reaction. 200 reactants 150 energy / kJ 100 products 50 progress of reaction Fig. 2.3 (i) Use Fig. 2.3 to calculate the energy given out in the reaction. energy given out = … kJ [1] (ii) Use Fig. 2.3 to calculate the activation energy for the reaction. activation energy = … kJ [1] (c) Ethanol can be made by • the catalytic addition of steam to ethene • fermentation. (i) Construct the balanced symbol equation for the addition of steam to ethene to make ethanol, C2H5OH. … + … … [2] (ii) Describe how ethanol is made by fermentation. … … … … [3] [Total: 9]

9 marks

Mark scheme: 2(a)(i) (B) 1 because the temperature change is greatest / 18 is greater than 9 / end temperature is highest (and starting temperature is the same) ; 2(a)(ii) more energy is given out during bond making than is taken in during bond breaking ticked ; 1 2(b)(i) 100 (kJ) ; 1 2(b)(ii) 50 (kJ) ; 1 2(c)(i) C2H4 + H2O → C2H5OH ;; 2 2(c)(ii) reference to yeast ; 3 (uses) glucose / (named) sugar (solution) ; absence of air or oxygen / anaerobic conditions / anaerobic respiration ;

This question in 0654/43 Oct/Nov 2022

11 Fig. 11.1 shows the structures of some compounds of carbon. H H H H H H C C C H H C C O H H H H H H compound A compound B H H H H H H H C C C C C C H H H H H compound C compound D Fig. 11.1 (a) State which compound A, B, C, or D is unsaturated. … [1] (b) State which one of these chemicals is used to test for unsaturation. aqueous barium chloride bromine limewater sodium hydroxide … [1] (c) Compound A is called propane. State the name of compound B. … [1] (d) Compound D is called poly(ethene). Poly(ethene) is a polymer made in an addition polymerisation reaction. (i) Complete the sentence to define a polymer. A polymer is a … … molecule formed from small units called … . [2] (ii) Draw the structure of the small unit (molecule) from which poly(ethene) is made. [1] (e) Fig. 11.2 shows the energy level diagram for the reaction between compound B and oxygen. reactants energy products progress of reaction Fig. 11.2 Energy is given out in this reaction. (i) Explain how Fig. 11.2 shows that energy is given out. … … [1] (ii) State the name of the type of reaction that gives out energy. … [1] (iii) Explain why energy is given out when compound B reacts with oxygen. Use ideas about bond breaking and bond making. … … … … [3] [Total: 11]

11 marks

Mark scheme: 11(a) C ; 1 11(b) bromine ; 1 11(c) ethanol ; 1 11(d)(i) long chain ; 2 monomers ; 11(d)(ii) 1 ; 11(e)(i) idea that products have less energy than the reactants ; 1 11(e)(ii) exothermic ; 1 11(e)(iii) bond breaking is endothermic / owtte ; 3 bond making is exothermic / owtte ; more energy is given out (in bond making) than is taken in (in bond breaking) ;

This question in 0654/42 Feb/March 2023

11 Look at the structures of the carbon compounds shown in Fig. 11.1. H H H H C C H C C O H H H H H A B H H H H H H H H C C H H C C C H C C H H H H H H H C D E Fig. 11.1 (a) (i) State which compound is made by the catalytic addition of steam to compound A. Choose from B, C, D or E. … [1] (ii) State which compound is made when compound A reacts with hydrogen gas, H2. Choose from B, C, D or E. … [1] (iii) State which compound reacts with bromine to form C2H4Br2. Choose from A, B, C, D or E. … [1] (iv) State which compound forms compound E in an addition polymerisation reaction. Choose from A, B, C or D. … [1] (b) Fig. 11.2 represents the formation of the polymer nylon from two monomers, X and Y. Nylon is made in a condensation polymerisation reaction. O O H H C C + N N HO OH H H monomer X monomer Y O O O N C C N N C H H H nylon Fig. 11.2 Describe how monomer X and monomer Y react together to make nylon. Use the information in Fig. 11.2 in your answer. … … … … … [3] [Total: 7]

7 marks

Mark scheme: 11(a)(i) B ; 1 11(a)(ii) C ; 1 11(a)(iii) A ; 1 11(a)(iv) A ; 1 11(b) any three from: idea that C on monomer X and N on monomer Y join ; idea that -OH group is lost from the monomer X ; idea that -H is lost from monomer Y ; idea that water is eliminated ; AVP ; 3

This question in 0654/41 May/June 2023

8 Fig. 8.1 shows the structures of three carbon compounds. H H C C H H ethene H H H O H C C H C C O H O H H H H ethanoic acid ethanol Fig. 8.1 (a) Ethene is an unsaturated hydrocarbon. Explain how the structure of ethene shows that ethene is an unsaturated hydrocarbon. unsaturated … … hydrocarbon … … [2] (b) Ethene, C2H4, reacts with hydrogen to make an alkane. Write the balanced symbol equation for this reaction. … [2] (c) Complete the dot‑and‑cross diagram in Fig. 8.2 to show the bonding in ethene. Only show the outer‑shell electrons. H H C C H H Fig. 8.2 [2] (d) Ethanol is made by fermentation. State one condition for making ethanol by fermentation. … [1] (e) Ethanol can also be made from ethene in an addition reaction. Complete the symbol equation for this reaction. C2H4 + ……… C2H5OH [1] (f) A scientist makes a solution of ethanol. 250 cm3 of the solution contains 5.75 g of ethanol. Calculate the concentration of the ethanol solution in mol / dm3. [Ar: C, 12; H, 1; O, 16] concentration of ethanol solution = … mol / dm3 [4] [Total: 12]

12 marks

Mark scheme: 8(a) contains a double (carbon to carbon) bond ; contains only hydrogen and carbon (atoms) / AW ; 2 8(b) C2H4 + H2  C2H6 ;; 2 8(c) ;; 2 Question Answer Marks 8(d) absence of air / no oxygen / anaerobic / yeast / sugar or glucose / water / warm temperature ; 1 8(e) H2O ; 1 8(f) (Mr of C2H5OH) = 46 ; (moles of C2H5OH) = 5.75 ÷ 46 = 0.125 ; 250 cm3 = 250 ÷ 1000 = 0.250 dm3 ; (concentration of C2H5OH) = 0.125 ÷ 0.25 = 0.5 mol / dm³ ; 4

This question in 0654/42 May/June 2024

2 Fig. 2.1 shows the displayed formulae of some carbon compounds. H H H H C C H C C H H H H H A B H H H H H H C C C H H C C O H H H H H H C D Fig. 2.1 (a) State which compound in Fig. 2.1 is not a hydrocarbon. Explain your answer. compound … explanation … … … [2] (b) State which compound in Fig. 2.1 will decolourise aqueous bromine. … [1] (c) Compound D is used as a fuel. State one other use of compound D. … [1] (d) Compound C is a saturated compound. State what is meant by saturated. … … [1] (e) Compound C, C3H8, undergoes complete combustion in oxygen. Construct the balanced symbol equation for this reaction. … [2] (f) Compound A is ethene. Complete Fig. 2.2 to show the displayed formula of the polymer poly(ethene). C C Fig. 2.2 [1] (g) The formation of poly(ethene) from ethene is an example of addition polymerisation. Explain the differences between addition polymerisation and condensation polymerisation. … … … … [2] [Total: 10]

10 marks

Mark scheme: 2(a) D ; 2 contains oxygen / does not contain only carbon and hydrogen ; 2(b) A ; 1 2(c) solvent ; 1 2(d) contains only C-C single bonds ; 1 2(e) C3H8 + 5O2 → 3CO2 + 4H2O 2 correct formulae (reactants in either order and products in either order) ; balanced correctly ; 2(f) 1 2(g) addition polymerisation 2 only occurs in unsaturated monomers or monomers that contain C=C bonds / idea that involves the addition of many (identical) monomers (to make a long chained polymer) / monomers have one functional group / forms the polymer molecule only ; condensation polymerisation idea that two different monomers join together / (forms the polymer molecule and one) water molecule (per linkage) / monomers have two functional groups (one at each end) ;

This question in 0654/43 Oct/Nov 2024

7 Look at the structures of the carbon compounds shown in Fig. 7.1. H H H Cl H H C C C C C H H H H n A B H H O H H O H H H C C O H C C N C C N H H H H n C D Fig. 7.1 (a) (i) State which compound is a hydrocarbon. Choose from A, B, C or D. … [1] (ii) State which compound is propene. Choose from A, B, C or D. … [1] (iii) State which compound is made from the reaction of ethene with steam in the presence of an acid catalyst. Choose from A, B, C or D. … [1] (iv) State which compound is made in a condensation polymerisation reaction. Choose from A, B, C or D. … [1] (b) Compound C, C2H5OH, completely combusts in oxygen. Construct the balanced symbol equation for the reaction. … [2] (c) A mixture containing 11.2 g of another carbon compound, C4H8, is allowed to react with 0.6 g of hydrogen, H2. C4H8 + H2 C4H10 Show, by calculation, that C4H8 is the limiting reactant. [Ar: C, 12; H, 1] C4H8 is the limiting reactant because … … [3] (d) Hydrogen, H2, is a simple covalent molecule. Complete the dot-and-cross diagram to show the bonding in a hydrogen molecule. H H [1] [Total: 10]

10 marks

Mark scheme: 7(a)(i) A; 1 7(a)(ii) A; 1 7(a)(iii) C; 1 7(a)(iv) D; 1 7(b) C2H5OH + 3O2 → 2CO2 + 3H2O 2 correct formulae; correct balancing; 7(c) moles of C4H8 = 11.2 = 0.2; 3 56 moles of H2 = 0.6 = 0.3; 2 (C4H8 is limiting because) 0.2 mol is less than the 0.3 mol of H2; 7(d) 1 ; ;

This question in 0654/43 May/June 2025