Alkanes — Paper 3 · IGCSE Science - Combined 0653

8 (a) (i) Copper is extracted when copper oxide is heated with carbon. Carbon dioxide is produced and released into the air. Complete the word equation for this reaction. copper oxide + + [1] (ii) Fossil fuels also release carbon dioxide during combustion. Suggest one other process that releases carbon dioxide into the air. … [1] (iii) Natural gas is a fossil fuel. Name one solid fossil fuel and one liquid fossil fuel. solid … liquid … [2] (b) Fig. 8.1 shows the structure of a molecule of compound X. H H H C C O H H H Fig. 8.1 (i) Name compound X. … [1] (ii) State what is meant by a hydrocarbon. … … [1] (iii) Explain why compound X is not a hydrocarbon. … … [1]

7 marks

Mark scheme: 8(a)(i) ; (copper oxide) + carbon → copper + carbon dioxide 1 8(a)(ii) respiration / (reaction of) acid + carbonate / thermal_decomposition / fermentation ; 1 8(a)(iii) (solid) coal ; (liquid) petroleum ; 2 8(b)(i) ethanol ; 1 8(b)(ii) compound / molecule containing / of only carbon and hydrogen ; 1 8(b)(iii) (because it) contains oxygen / O (as well as C and H) ; 1

This question in 0653/32 Oct/Nov 2017

5 (a) Pure water can be separated from sea water using the apparatus shown in Fig. 5.1. water out condenser cold water in sea water pure water heat Fig. 5.1 (i) Name this process. … [1] (ii) Describe the change in the temperature of the pure water as it passes through the condenser. … [1] (b) The purification of a water supply involves filtration and chlorination. Explain how filtration and chlorination purify the water supply. filtration … … chlorination … … [2] (c) Petroleum is separated into different fractions, as shown in Fig. 5.2. refinery gas gasoline gas oil hot petroleum Fig. 5.2 (i) State one use for refinery gas and one use for gas oil. refinery gas … gas oil … [2] (ii) Gasoline is a mixture of hydrocarbons. Explain what is meant by a hydrocarbon. … … [2] (d) The structures of six compounds are shown in Fig. 5.3. H H H O C O H C H H C C H H H H A B C H H H H C C H C C OH O H H H H H H D E F Fig. 5.3 (i) Using letters A to F, identify the two products of the complete combustion of hydrocarbons. … and … [1] (ii) Using letters A to F, identify the main constituent of natural gas. … [1]

10 marks

Mark scheme: 5(a)(i) distillation ; 1 5(a)(ii) decrease ; 1 5(b) (filtration) remove (named) solids ; (chlorination) kill microbes / bacteria / sterilizes ; 2 5(c)(i) (refinery gas) bottled gas / heating / cooking ; (gas oil) diesel fuel / diesel engines / diesel vehicles ; 2 5(c)(ii) compound / molecule containing hydrogen and carbon ; only (C and H); 2 5(d)(i) A F ; 1 5(d)(ii) B ; 1

This question in 0653/33 Oct/Nov 2017

2 A student investigates the combustion of a hydrocarbon, as shown in Fig. 2.1. Gases move through the apparatus in the direction shown by the arrows. gases drawn through X air solution bubbles drawn X Y ice in bath hydrocarbon Fig. 2.1 (a) The student thinks that carbon dioxide and water are formed when the hydrocarbon burns. (i) Suggest a chemical that the student uses at position X to test for the presence of water. … [1] (ii) The student uses solution Y to test for carbon dioxide. Identify solution Y. … [1] (b) Hexane is a hydrocarbon. The products of the complete combustion of hexane are carbon dioxide and water. Complete the word equation for this reaction. hexane + + [2] (c) Name the hydrocarbon that is the main constituent of natural gas. … [1] (d) (i) Carbon and hydrogen are non‑metallic elements. State the type of bond that forms between atoms of these two elements. … [1] (ii) Draw the structure of a molecule of ethane, C2H6. [2] (iii) An atom of carbon is represented by: 126C State the atomic number and the number of neutrons in this atom. atomic number … number of neutrons … [2]

10 marks

Mark scheme: 2 2( 2 2 2 2( 2( (a)(i) white / (a)(ii) limewa 2(b) LHS ; RHS ( 2(c) metha (d)(i) covale (d)(ii) C – C Six C – (d)(iii) (atomi (numb / anhydrous copp ater ; either order) ; ne ; ent ; bond ; – H bonds ; c number) ber of neutrons) per sulphate or a (hexan 6 ; 6 ; anhydrous / blue ne) + oxy e cobalt chloride ygen Î c d ; carbon dioxide + water 1 1 2 1 1 2 2

This question in 0653/32 May/June 2018

2 A student investigates the combustion of a hydrocarbon, as shown in Fig. 2.1. Gases move through the apparatus in the direction shown by the arrows. gases drawn through X air solution bubbles drawn X Y ice in bath hydrocarbon Fig. 2.1 (a) The student thinks that carbon dioxide and water are formed when the hydrocarbon burns. (i) Suggest a chemical that the student uses at position X to test for the presence of water. … [1] (ii) The student uses solution Y to test for carbon dioxide. Identify solution Y. … [1] (b) Hexane is a hydrocarbon. The products of the complete combustion of hexane are carbon dioxide and water. Complete the word equation for this reaction. hexane + + [2] (c) Name the hydrocarbon that is the main constituent of natural gas. … [1] (d) (i) Carbon and hydrogen are non‑metallic elements. State the type of bond that forms between atoms of these two elements. … [1] (ii) Draw the structure of a molecule of ethane, C2H6. [2] (iii) An atom of carbon is represented by: 126C State the atomic number and the number of neutrons in this atom. atomic number … number of neutrons … [2]

10 marks

Mark scheme: 2 2( 2 2 2 2( 2( (a)(i) white / (a)(ii) limewa 2(b) LHS ; RHS ( 2(c) metha (d)(i) covale (d)(ii) C – C Six C – (d)(iii) (atomi (numb / anhydrous copp ater ; either order) ; ne ; ent ; bond ; – H bonds ; c number) ber of neutrons) per sulphate or a (hexan 6 ; 6 ; anhydrous / blue ne) + oxy e cobalt chloride ygen Î c d ; carbon dioxide + water 1 1 2 1 1 2 2

This question in 0653/33 May/June 2018

5 (a) Natural gas and coal are fossil fuels. (i) Name one other fossil fuel. … [1] (ii) Name the main constituent of natural gas. … [1] (b) Ethane, C2H6, is an alkane. (i) Describe the chemical properties of alkanes. … … [1] (ii) Complete the structure of a molecule of ethane. H C [2] (c) The atomic numbers and mass numbers of carbon and of hydrogen are shown in Table 5.1. Table 5.1 atomic number mass number carbon 6 12 hydrogen 1 1 (i) Define atomic number. … … [1] (ii) Complete Table 5.2 to describe the particles in an atom. Table 5.2 particle position in atom relative charge relative mass electron –1 neutron in nucleus proton 1 [3]

9 marks

Mark scheme: 5(a)(i) petroleum ; 1 5(a)(ii) methane ; 1 5(b)(i) unreactive / (only) burn / combust ; 1 5(b)(ii) C – C single bond ; All else correct ; 2 5(c)(i) number of protons (in an atom / nucleus) ; 1 5(c)(ii) 2 or 3 correct entries = 1 mark 4 or 5 correct entries = 2 marks All correct = 3 marks 3

This question in 0653/32 Oct/Nov 2018

5 (a) Petroleum contains hydrocarbons. These are separated into useful fractions by fractional distillation, as shown in Fig. 5.1. refinery gas gasoline naphtha gas oil petroleum bitumen Fig. 5.1 (i) Identify a fraction shown in Fig. 5.1 used for fuel in cars. … [1] (ii) Identify a fraction shown in Fig. 5.1 used for bottled gas for heating and cooking. … [1] (b) (i) Name the type of hydrocarbon which contains only single bonds. … [1] (ii) Identify the products of the complete combustion of hydrocarbons. … and … [1] (c) Compound X is made from large hydrocarbon molecules in a reaction called cracking. Compound X reacts with aqueous bromine, changing it from orange to colourless. Molecules of compound X join together to form a polymer. (i) Suggest the identity of compound X. … [1] (ii) State the type of polymerisation in which molecules of compound X form a polymer. … [1] (d) Hydrocarbon molecules contain atoms of the elements carbon and hydrogen only. (i) A carbon atom has 6 electrons. Complete Fig. 5.2 to show the electronic structure of this carbon atom. Fig. 5.2 [1] (ii) Complete the dot-and-cross diagram in Fig. 5.3 to show the covalent bond in a molecule of hydrogen gas, H2. H H Fig. 5.3 [1] (iii) State why covalent bonds, rather than ionic bonds, form between carbon atoms and hydrogen atoms. … … [1] [Total: 9]

9 marks

Mark scheme: 5(a)(i) gasoline ; 1 5(a)(ii) refinery gas ; 1 5(b)(i) alkane(s) / saturated ; 1 5(b)(ii) carbon dioxide / CO2 and water / H2O ; 1 5(c)(i) ethene / C2H4 / any named alkene / any correct alkene formula / alkene ; 1 5(c)(ii) addition (polymerisation) ; 1 5(d)(i) 2,4 arrangement ; 1 Question Answer Marks 5(d)(ii) H H 1 5(d)(iii) they / carbon and hydrogen are (both) non-metals / it is a simple molecule ; 1 X •

This question in 0653/32 May/June 2019

2 Petroleum is a mixture of compounds which are separated in a fractional distillation column. Process X changes molecules in one fraction, as shown in Fig. 2.1. fractional process X distillation column products strong heat petroleum Fig. 2.1 (a) The products of process X include alkenes. (i) Identify process X. … [1] (ii) Describe the colour change that is seen when aqueous bromine is mixed with an alkene. from … to … [2] (iii) Name the substance that is formed by the addition polymerisation of ethene. … [1] (b) Most of the compounds in petroleum are alkanes. Alkanes and alkenes contain carbon and hydrogen atoms only. (i) Name the type of compound that contains carbon and hydrogen atoms only. … [1] (ii) State the type of chemical bond that forms between carbon and hydrogen atoms. … [1] (iii) Identify the two products of the complete combustion of alkanes. … and … [2] (iv) The formula of methane is CH4. Complete the dot‑and‑cross diagram to show the shared electron pairs in a molecule of methane. H C [2] [Total: 10]

10 marks

Mark scheme: 2(a)(i) cracking ; 1 2(a)(ii) (from) brown / orange / yellow / red-brown ; (to) colourless / lighter ; 2 2(a)(iii) poly(ethene) ; 1 2(b)(i) hydrocarbon ; 1 2(b)(ii) covalent ; 1 2(b)(iii) carbon dioxide / CO2 ; water / H2O ; 2 Question Answer Marks 2(b)(iv) three further hydrogen atoms drawn around the carbon atom ; one pair of electrons between each hydrogen and the carbon ; 2

This question in 0653/32 Oct/Nov 2019

2 Petroleum is a mixture of compounds which are separated in a fractional distillation column. Process X changes molecules in one fraction, as shown in Fig. 2.1. fractional process X distillation column products strong heat petroleum Fig. 2.1 (a) The products of process X include alkenes. (i) Identify process X. … [1] (ii) Describe the colour change that is seen when aqueous bromine is mixed with an alkene. from … to … [2] (iii) Name the substance that is formed by the addition polymerisation of ethene. … [1] (b) Most of the compounds in petroleum are alkanes. Alkanes and alkenes contain carbon and hydrogen atoms only. (i) Name the type of compound that contains carbon and hydrogen atoms only. … [1] (ii) State the type of chemical bond that forms between carbon and hydrogen atoms. … [1] (iii) Identify the two products of the complete combustion of alkanes. … and … [2] (iv) The formula of methane is CH4. Complete the dot‑and‑cross diagram to show the shared electron pairs in a molecule of methane. H C [2] [Total: 10]

10 marks

Mark scheme: 2(a)(i) cracking ; 1 2(a)(ii) (from) brown / orange / yellow / red-brown ; (to) colourless / lighter ; 2 2(a)(iii) poly(ethene) ; 1 2(b)(i) hydrocarbon ; 1 2(b)(ii) covalent ; 1 2(b)(iii) carbon dioxide / CO2 ; water / H2O ; 2 Question Answer Marks 2(b)(iv) three further hydrogen atoms drawn around the carbon atom ; one pair of electrons between each hydrogen and the carbon ; 2

This question in 0653/33 Oct/Nov 2019

5 Refinery gas, gasoline and gas oil are fuels obtained from petroleum in the process shown in Fig. 5.1. refinery gas gasoline gas oil petroleum Fig. 5.1 (a) Suggest one use for bottled refinery gas fuel. … [1] (b) Petroleum is a mixture that contains alkanes. Alkanes are saturated compounds that contain carbon and hydrogen atoms only. The complete combustion of alkanes forms water and one other compound. (i) Name the type of compound that contains carbon and hydrogen atoms only. … [1] (ii) Identify one other compound that is formed during the complete combustion of alkanes. … [1] (iii) Describe one chemical test for water and give the positive result. test … result … [2] (c) Methane, CH4, is an alkane. The structure of a molecule of methane is shown in Fig. 5.2. H H C H H Fig. 5.2 (i) Name the type of bonding in methane. … [1] (ii) Explain how bonds form between carbon atoms and hydrogen atoms in methane. Use ideas about electrons. … … [1] (d) Ethene is an alkene. Alkenes are unsaturated compounds. (i) Describe the difference in the structure of molecules of alkenes and alkanes. Use ideas about bonds. … … [1] (ii) Name the addition polymer that forms from ethene monomer units. … [1] [Total: 9]

9 marks

Mark scheme: 5(a) heating / cooking ; 1 5(b)(i) hydrocarbon ; 1 5(b)(ii) carbon dioxide ; 1 5(b)(iii) reagent copper sulfate OR cobalt chloride ; result (white to) blue OR (blue to) pink ; result must match the reagent 2 5(c)(i) covalent ; 1 5(c)(ii) shared (pair) ; 1 5(d)(i) alkenes double (bonds) and alkanes (only) single (bonds) ; 1 5(d)(ii) poly(ethene) ; 1

This question in 0653/32 Feb/March 2020

5 (a) Petroleum is separated using the process shown in Fig. 5.1. refinery gas gasoline gas oil petroleum Fig. 5.1 (i) Name the process shown in Fig. 5.1. … [1] (ii) Refinery gas and gas oil can be used as fuels. State one use for each of these fuels. refinery gas … gas oil … [2] (iii) Identify the greenhouse gas that forms during the complete combustion of gasoline. … [1] (b) Petroleum is a mixture of hydrocarbon molecules called alkanes. (i) Explain what is meant by hydrocarbon. … … [2] (ii) State the name of a process used to produce alkenes. … [1] (iii) Describe the difference between the bonding in alkanes and in alkenes. … … [1] (iv) Many ethene molecules combine to form poly(ethene). State the type of addition reaction that occurs. … [1] [Total: 9]

9 marks

Mark scheme: 5(a)(i) fractional distillation ; 1 5(a)(ii) (refinery gas) bottled gas / heating / cooking ; (gas oil) diesel (engines / fuel) ; 2 5(a)(iii) carbon dioxide / CO2 ; 1 Question Answer Marks 5(b)(i) (molecules / compounds) contain carbon and hydrogen (atoms) ; only ; 2 5(b)(ii) cracking ; 1 5(b)(iii) alkanes contain only single (bonds) / alkenes contain double (bonds) ; 1 5(b)(iv) (addition) polymerisation ; 1

This question in 0653/31 May/June 2020

5 (a) A liquid fuel contains atoms of carbon and hydrogen only. (i) State the type of compound which contains atoms of carbon and hydrogen only. … [1] (ii) Deduce the naturally occurring substance from which this liquid fuel is obtained. … [1] (iii) Deduce the type of chemical bond that forms between atoms of carbon and atoms of hydrogen. … [1] (b) Propene is a gas at room temperature and pressure. Fig. 5.1 shows the structure of a molecule of propene. H H H H C C C H H Fig. 5.1 (i) Deduce the formula of propene. … [1] (ii) Describe the effect, if any, of propene on aqueous bromine. … … [1] (iii) Complete the word equation for the complete combustion of propene. propene + + [2] (iv) Propene is transported as a liquid. Describe the difference between gaseous propene and liquid propene in terms of the separation of the molecules and the motion of the molecules. separation … … motion … … [2] [Total: 9]

9 marks

Mark scheme: 5(a)(i) hydrocarbon ; 1 5(a)(ii) petroleum ; 1 5(a)(iii) covalent ; 1 5(b)(i) C3H6 ; 1 5(b)(ii) decolourises / (from orange to) colourless ; 1 5(b)(iii) reactants correct = 1 mark products correct = 1 mark 2 Question Answer Marks 5(b)(iv) (separation) (gas molecules) greater separation / further apart ; (motion) (gas molecules) move faster ; 2

This question in 0653/32 May/June 2020

8 (a) Methane, CH4, is an alkane. (i) Methane is the main constituent of a fossil fuel. Name this fossil fuel. … [1] (ii) Name the type of chemical bonds in a molecule of methane. … [1] (iii) Fig. 8.1 is an incomplete dot-and-cross diagram of a molecule of methane. On Fig. 8.1, draw dots and crosses to show all of the outer shell electrons in a molecule of methane. H H C H H Fig. 8.1 [2] (b) A sample of refinery gas contains only alkane molecules. (i) Name the process used to obtain refinery gas from petroleum. … [1] (ii) Describe the effect, if any, of this sample of refinery gas on aqueous bromine. … [1] (c) Fossil fuels are used for heating. (i) State the type of chemical reaction that produces a temperature increase during the combustion of fossil fuels. … [1] (ii) Suggest the effect of the combustion of methane on the number of nitrogen molecules and on the number of oxygen molecules in a limited supply of air. nitrogen molecules … oxygen molecules … [2] (iii) During the combustion of fossil fuels, carbon dioxide is produced. State the test and the positive result for carbon dioxide. test … result … [2] [Total: 11]

11 marks

Mark scheme: 8(a)(i) natural gas ; 1 8(a)(ii) covalent ; 1 8(a)(iii) one bond shown correctly ; four bonds shown correctly ; 2 8(b)(i) fractional distillation ; 1 8(b)(ii) none / no effect / (stays) orange-brown ; 1 8(c)(i) exothermic ; 1 8(c)(ii) (nitrogen) no change / no effect / none ; (oxygen) decreases ; 2 8(c)(iii) (test) limewater ; (result) turns milky ; 2

This question in 0653/32 Oct/Nov 2020

8 (a) A molecule of methane is represented in Fig. 8.1. H H C H H Fig. 8.1 (i) Name the type of chemical bond present in this molecule. … [1] (ii) Describe how the bonds in this molecule form. Use ideas about electrons in your answer. … … [1] (iii) State the formula of methane. … [1] (b) During the complete combustion of methane, two gases are produced. Gas A changes blue cobalt(II) chloride paper to pink. Gas B turns limewater milky. (i) Identify the gas in the air which is required for the complete combustion of methane. … [1] (ii) Identify gas A and gas B. gas A … gas B … [2] (c) Methane is a common component of refinery gas. (i) Name the mixture from which refinery gas is separated. … [1] (ii) Name the process by which refinery gas is separated. … [1] (iii) Identify one use for refinery gas. … [1] [Total: 9]

9 marks

Mark scheme: 8(a)(i) covalent ; 1 8(a)(ii) (electrons are) shared ; 1 8(a)(iii) CH4 ; 1 8(b)(i) oxygen / O2 ; 1 8(b)(ii) (gas A) water (vapour) / H2O ; (gas B) carbon dioxide / CO2 ; 2 8(c)(i) petroleum ; 1 8(c)(ii) fractional distillation ; 1 8(c)(iii) heating / cooking ; 1

This question in 0653/33 Oct/Nov 2020

2 Natural gas and petroleum are two types of fossil fuel. (a) Name one other fossil fuel. … [1] (b) State the main constituent of natural gas. … [1] (c) Petroleum is separated by the process shown in Fig. 2.1. refinery gas gasoline naphtha gas oil petroleum bitumen Fig. 2.1 (i) Name this process. … [1] (ii) State one use for bitumen. … [1] (d) Ethane and ethene are both hydrocarbons. Ethane is an alkane. Ethene is an alkene. (i) Two compounds are made during the complete combustion of ethane and of ethene. Water is one of these compounds. Identify the other compound. … [1] (ii) Describe one difference between molecules of ethane and molecules of ethene. … … [1] (e) The structure of a molecule of another hydrocarbon is shown in Fig. 2.2. H H H H C C C H H H H Fig. 2.2 Deduce the formula of this hydrocarbon. … [1] [Total: 7]

7 marks

Mark scheme: 2(a) coal ; 1 2(b) methane / CH4 ; 1 2(c)(i) fractional distillation ; 1 2(c)(ii) (for making) roads ; 1 2(d)(i) carbon dioxide / CO2 ; 1 2(d)(ii) ethene, is unsaturated / contains double bonds ; 1 2(e) C3H8 ; 1

This question in 0653/32 Feb/March 2021

8 The structures of ethane and of ethene are shown in Fig. 8.1. H H H H H C C H C C H H H H ethane ethene Fig. 8.1 (a) Ethane is an alkane. Ethene is an alkene. Describe one similarity and one difference between the chemical bonds in alkane molecules and in alkene molecules. similarity … … difference … … [2] (b) During the complete combustion of ethane, water and one other substance form. (i) Identify this other substance. … [1] (ii) Describe one chemical test for water and state the observation for a positive result. test … observation … [2] (iii) Explain why the combustion of ethane is described as an oxidation reaction. … … [1] (c) Fractional distillation of petroleum produces naphtha. Cracking naphtha produces ethene. Addition polymerisation of ethene produces polymer Y. Name polymer Y. … [1] [Total: 7]

7 marks

Mark scheme: 8(a) similarity: covalent bonds ; difference: alkanes only single (bonds) / alkenes contain double (bonds) ; 2 8(b)(i) carbon dioxide / CO2 ; 1 Question Answer Marks 8(b)(ii) test: copper(II) sulfate OR cobalt(II) chloride ; result: white to blue blue to pink ; RESULT MUST MATCH TEST 2 8(b)(iii) (ethane / molecules / carbon / hydrogen / it) gains oxygen ; 1 8(c) poly(ethene) ; 1

This question in 0653/32 May/June 2021

8 Methane, CH4, is a hydrocarbon. (a) State what is meant by hydrocarbon. … … [2] (b) Methane is an alkane. An alkane contains only single covalent bonds. Fig. 8.1 is a dot-and-cross diagram of a molecule of methane, CH4. Only the outer shell electrons are shown. H × H × C × H × H Fig. 8.1 Use Fig. 8.1 to describe what is meant by single covalent bonds. … … … [2] (c) The complete combustion of methane produces carbon dioxide and water. (i) Balance the equation for the complete combustion of methane. CH4 + … O2 CO2 + … H2O [2] (ii) State and explain whether the carbon in methane is oxidised or reduced in this reaction. carbon … explanation … … [1] (iii) Explain why argon, a noble gas, does not react with oxygen. Use ideas about electronic structure in your answer. … … [1] (d) Describe how the bonding in alkenes is different from the bonding in alkanes. … … [1] [Total: 9]

9 marks

Mark scheme: 8(a) (compound) containing carbon (atoms) and hydrogen (atoms) ; only ; 2 8(b) single: one pair of electrons / one dot and one cross ; covalent: electrons are shared / electrons inside two circles ; 2 8(c)(i) 2 ; 2 ; 2 8(c)(ii) oxidised AND gains oxygen ; 1 8(c)(iii) atoms of argon have full outer shells / 8 electrons in outer shells ; 1 8(d) alkenes contain a double bond / C=C (whereas alkanes contain only single bonds) ; 1

This question in 0653/31 Oct/Nov 2021

8 Petroleum is separated into useful fractions by the process shown in Fig. 8.1. refinery gas gasoline naphtha gas oil petroleum bitumen Fig. 8.1 Each fraction is a mixture of different hydrocarbons. (a) These hydrocarbons are generally unreactive. They burn in air, but they do not react with aqueous bromine. (i) Name the type of hydrocarbons that do not react with aqueous bromine. … [1] (ii) State one use for gas oil. … [1] (b) Naphtha is used to make ethene. (i) Name the process used to make ethene from naphtha. … [1] (ii) Complete the word equation for the complete combustion of ethene, C2H4. ethene + + [2] (c) Ethene is used to make a polymer. (i) State the name of the polymer that is made from ethene. … [1] (ii) State the type of polymerisation reaction that makes this polymer from ethene. … [1] [Total: 7]

7 marks

Mark scheme: 8(a)(i) alkane(s) ; 1 8(a)(ii) diesel (engine) fuel ; 1 8(b)(i) cracking ; 1 Question Answer Marks 8(b)(ii) ;; All three boxes correct (2) Two boxes correct (1) One or no boxes correct (0) 2 8(c)(i) poly(ethene) ; 1 8(c)(ii) addition (polymerisation) ; 1

This question in 0653/33 May/June 2022

5 (a) Ethane, C2H6, is an alkane. It is one of the saturated hydrocarbons present in refinery gas obtained from petroleum, as shown in Fig. 5.1. refinery gas petroleum Fig. 5.1 (i) State one use of refinery gas. … [1] (ii) Explain what is meant by hydrocarbon and saturated. hydrocarbon … … saturated … … [2] (b) Ethene, C2H4, is an unsaturated hydrocarbon. (i) State the process that produces unsaturated hydrocarbons from petroleum fractions. … [1] (ii) Describe the change in colour of aqueous bromine when it is added to ethene. from … to … [1] (iii) Complete the balanced equation for the complete combustion of ethene. C2H4 + …. O2 …. CO2 + …. H2O [2] (iv) State the name of the substance that is formed when many ethene monomer units join together. … [1] [Total: 8]

8 marks

Mark scheme: 5(a)(i) (bottled) gas for (domestic), heating / cooking ; 1 5(a)(ii) (hydrocarbon) molecule / compound, containing hydrogen / H and carbon / C only ; (saturated) only single bonds (between carbon atoms) / no double bonds ; 2 5(b)(i) cracking ; 1 5(b)(ii) (from) brown/orange/red-brown (to) colourless ; 1 5(b)(iii) (C2H4) + ..3.. O2  ..2.. CO2 + ..2.. H2O ;; LHS (1) RHS (1) 2 Question Answer Marks 5(b)(iv) poly(ethene) ; 1

This question in 0653/31 May/June 2023

8 (a) Methane, CH4, is the main constituent of natural gas. (i) Complete the word equation for the complete combustion of methane. methane + + water [1] (ii) Complete the dot‑and‑cross diagram in Fig. 8.1 to show the arrangement of electrons in a molecule of water. Show only the outer shell electrons. H O H Fig. 8.1 [2] (b) Ethene is an unsaturated hydrocarbon. Aqueous Y is an orange solution that is decolourised by ethene. It is used as a test for ethene. (i) State what is meant by unsaturated. … … [1] (ii) Identify Y. … [1] (iii) State the type of polymerisation that produces poly(ethene) from ethene. … [1] (c) At –120 °C methane is a gas and ethene is a liquid. Describe two differences between the particles in a gas and a liquid. 1 … … 2 … … [2] [Total: 8]

8 marks

Mark scheme: 8(a)(i) methane + oxygen  carbon dioxide + water ; 1 8(a)(ii) both correct bonding pairs ; molecule fully correct, i.e. four additional electrons on O and no extra electrons ; 2 8(b)(i) contains a double bond ; 1 8(b)(ii) (aqueous) bromine / Br2 ; 1 8(b)(iii) addition ; 1 8(c) any two from: separation: gas particles are, far apart / separated / not touching / spread out / liquid particles are, close together / touching / not spread out / not separated ; movement: gas particles, move fast(er) / move freely / move in all directions / move randomly / liquid particles, move (more) slowly / move over each other ; forces: gas particles have, no / weak forces of attraction between particles / liquids particles have stronger forces of attraction ; 2

This question in 0653/32 May/June 2023

2 A student investigates the combustion of natural gas, as shown in Fig. 2.1. … water burning natural gas Fig. 2.1 (a) The student measures the temperature of the water as the natural gas burns. (i) Complete Fig. 2.1 by labelling the apparatus that is used to measure temperature. [1] (ii) State the name of the hydrocarbon that is the main constituent of natural gas. … [1] (iii) State what is meant by hydrocarbon. … … [1] (b) During this investigation, the combustion of natural gas causes the temperature of the water in the beaker to increase. State the name of the type of chemical reaction that causes an increase in temperature. … [1] (c) One of the products of the combustion of natural gas is carbon dioxide, CO2. (i) Explain why this combustion reaction is a redox reaction. … … [1] (ii) State the type of chemical bond formed in a molecule of carbon dioxide. … [1] (iii) Describe a test for carbon dioxide and state the observation for a positive result. test … … observation … [2] [Total: 8]

8 marks

Mark scheme: 2(a)(i) thermometer ; 1 2(a)(ii) methane ; 1 2(a)(iii) (molecule / compound, that) contains hydrogen and carbon (atoms) only ; 1 2(b) exothermic ; 1 2(c)(i) carbon / C / (natural) gas, gains oxygen / O / O2 ; 1 2(c)(ii) covalent ; 1 2(c)(iii) (test) (pass through) limewater ; (observation) (turns) milky / cloudy ; 2

This question in 0653/33 May/June 2023

8 Ethene is an example of an alkene. All alkenes are unsaturated hydrocarbons. (a) Describe what is meant by unsaturated and hydrocarbon. unsaturated … … hydrocarbon … … [2] (b) Ethene is a gas at room temperature and pressure. Describe the arrangement and motion of particles in gases. arrangement … … motion … … [2] (c) Table 8.1 shows the melting point and boiling point of ethene. Table 8.1 melting point / °C boiling point / °C –169 –104 Predict the state of ethene at –190 °C. Give a reason for your answer. state … reason … … [1] (d) The reaction between ethene and oxygen is exothermic. The word equation for this reaction is shown. ethene + oxygen carbon dioxide + water State the type of chemical reaction shown in this equation. … [1] (e) Poly(ethene) is formed from ethene. Complete the sentence about this process. Poly(ethene) is formed by the … polymerisation of monomer … . [2] [Total: 8]

8 marks

Mark scheme: 8(a) unsaturated: 2 contains a double (C=C) covalent bond ; hydrocarbon: contains carbon AND hydrogen only ; 8(b) arrangement: 2 far apart / not touching / random ; motion: move quickly ; 8(c) solid AND 1 −190 °C is less than melting point / melting point is higher than −190 °C ; 8(d) combustion ; 1 8(e) addition ; 2 units / molecules ;

This question in 0653/32 Feb/March 2024

8 (a) The fossil fuel petroleum is a liquid mixture of hydrocarbons. (i) Complete the sentence about hydrocarbons. Hydrocarbons are molecules that contain … and … only. [1] (ii) Describe the arrangement and motion of particles in a liquid. arrangement … … motion … … [2] (iii) Explain why the change in state from a liquid to a gas is described as a physical change. … … [1] (b) A diagram of the equipment used to separate petroleum is shown in Fig. 8.1. column petroleum Fig. 8.1 State the name of the separation process that uses this equipment. … [1] (c) Ethene is an unsaturated hydrocarbon. (i) Describe what is meant by unsaturated. … [1] (ii) Naphtha is obtained from petroleum. Naphtha undergoes a process to produce ethene. State the name of the process that produces ethene from naphtha. … [1] (iii) State the name of the type of chemical reaction that changes ethene into poly(ethene). … [1] [Total: 8]

8 marks

Mark scheme: 8(a)(i) carbon and hydrogen ; 1 8(a)(ii) (arrangement) close together / random ; (motion) move around each other ; 2 8(a)(iii) no new substance is made / can be reversed ; 1 8(b) fractional distillation ; 1 8(c)(i) contains a (C=C) double bond ; 1 8(c)(ii) cracking ; 1 8(c)(iii) addition polymerisation ; 1

This question in 0653/33 May/June 2024

5 (a) Complete the sentences about air. Use the words from the list. Each word may be used once, more than once or not at all. compound methane mixture nitrogen oxygen • Air is a … . • The gas with the largest percentage in clean air is … . • 21% of clean air is … . [3] (b) Fig. 5.1 shows models of the molecular structures of two air pollutants, A and B. Key sulfur atom oxygen atom carbon atom pollutant A pollutant B Fig. 5.1 (i) State the name of pollutant A. … [1] (ii) Pollutant B is carbon monoxide. State one effect of carbon monoxide on human health. … [1] (c) Methane is a greenhouse gas. Fig. 5.2 shows the molecular structure of methane. H H C H H Fig. 5.2 (i) State the group of hydrocarbons to which methane belongs. … [1] (ii) Draw lines to show which descriptions are true for methane. One line has been drawn for you. description main constituent of natural gas generally unreactive methane hydrocarbon unsaturated decolourises aqueous bromine [2] (iii) Complete the dot-and-cross diagram in Fig. 5.3 to show the bonding in a methane molecule, CH4. Show all the outer shell electrons. H H C H H Fig. 5.3 [1] [Total: 9]

9 marks

Mark scheme: 5(a) mixture ; 3 nitrogen ; oxygen ; 5(b)(i) sulfur dioxide ; 1 5(b)(ii) fatigue / headache / drowsiness / confusion / dizziness / death ; 1 5(c)(i) alkane ; 1 5(c)(ii) line drawn to ‘generally unreactive’ ; 2 line drawn to ‘hydrocarbon’ ; 5(c)(iii) 1 bonding pair between each hydrogen and the carbon ;

This question in 0653/32 Oct/Nov 2024

5 (a) Complete the sentences about air. Use the words from the list. Each word may be used once, more than once or not at all. compound methane mixture nitrogen oxygen • Air is a … . • The gas with the largest percentage in clean air is … . • 21% of clean air is … . [3] (b) Fig. 5.1 shows models of the molecular structures of two air pollutants, A and B. Key sulfur atom oxygen atom carbon atom pollutant A pollutant B Fig. 5.1 (i) State the name of pollutant A. … [1] (ii) Pollutant B is carbon monoxide. State one effect of carbon monoxide on human health. … [1] (c) Methane is a greenhouse gas. Fig. 5.2 shows the molecular structure of methane. H H C H H Fig. 5.2 (i) State the group of hydrocarbons to which methane belongs. … [1] (ii) Draw lines to show which descriptions are true for methane. One line has been drawn for you. description main constituent of natural gas generally unreactive methane hydrocarbon unsaturated decolourises aqueous bromine [2] (iii) Complete the dot-and-cross diagram in Fig. 5.3 to show the bonding in a methane molecule, CH4. Show all the outer shell electrons. H H C H H Fig. 5.3 [1] [Total: 9]

9 marks

Mark scheme: 5(a) mixture ; 3 nitrogen ; oxygen ; 5(b)(i) sulfur dioxide ; 1 5(b)(ii) fatigue / headache / drowsiness / confusion / dizziness / death ; 1 5(c)(i) alkane ; 1 5(c)(ii) line drawn to ‘generally unreactive’ ; 2 line drawn to ‘hydrocarbon’ ; 5(c)(iii) 1 bonding pair between each hydrogen and the carbon ;

This question in 0653/33 Oct/Nov 2024

5 Table 5.1 shows the percentage of gases in a sample of natural gas. Table 5.1 gas percentage methane 83 ethane 9 propane 5 butane 2 nitrogen 0.5 other gases (a) (i) Use the data in Table 5.1 to calculate the percentage of other gases in the sample of natural gas. percentage of other gases = … [1] (ii) State the named gas in Table 5.1 that is in clean air. … [1] (b) Name the two products of the complete combustion of methane. 1 … 2 … [2] (c) Propane and butane are in the refinery gas fraction obtained from petroleum. Tick (3) one use of refinery gas. added to water to kill microbes fuel used for heating and cooking fuel used in diesel engines used to make road surfaces [1] (d) Fig. 5.1 shows the structure of ethane. H H H C C H H H Fig. 5.1 (i) Use Fig. 5.1 to explain why ethane is a saturated molecule. … … [1] (ii) State the number of electrons shared between the carbon atoms in a molecule of ethane. … [1] [Total: 7]

7 marks

Mark scheme: 5(a)(i) 0.5 (%) ; 1 5(a)(ii) nitrogen ; 1 5(b) carbon dioxide ; 2 water ; either order 5(c) fuel used for heating and cooking ; 1 more than one answer ticked = 0 marks 5(d)(i) the (C-C) bond is single / contains single bonds only ; 1 5(d)(ii) two / 2 ; 1

This question in 0653/32 Feb/March 2025

6 (a) The formulas of some compounds of carbon are shown. C2H4 CaCO3 CH4 CO CO2 Use the formulas of these compounds to answer the following questions. Each formula may be used once, more than once or not at all. State which compound: (i) decolourises aqueous bromine … [1] (ii) is the main constituent of natural gas … [1] (iii) forms poly(ethene) in an addition polymerisation reaction … [1] (iv) is a product of the complete combustion of alkanes and leads to global warming … [1] (v) is a toxic gas formed by incomplete combustion … [1] (vi) is a waste gas produced from digestion in animals … [1] (vii) is an acidic oxide. … [1] (b) State what is meant by a hydrocarbon. … … [1] (c) Bitumen and refinery gas are obtained from petroleum. Name one use of: bitumen … refinery gas. … [2] (d) Coal is a fossil fuel. During the combustion of coal, a compound that contains sulfur is made. Name this compound. … [1] [Total: 11]

11 marks

Mark scheme: 6(a)(i) C2H4 ; 1 6(a)(ii) CH4 ; 1 6(a)(iii) C2H4 ; 1 6(a)(iv) CO2 ; 1 6(a)(v) CO ; 1 6(a)(vi) CH4 ; 1 6(a)(vii) CO2 ; 1 6(b) (a compound that contains) carbon and hydrogen only ; 1 6(c) (bitumen) road surfaces ; 2 (refinery gas) heating / cooking ; 6(d) sulfur dioxide ; 1

This question in 0653/31 May/June 2025

5 (a) Fig. 5.1 shows an organic compound. H H H Cl H H C C C C C H H H H H H Fig. 5.1 (i) Deduce the molecular formula of the organic compound shown in Fig. 5.1. … [1] (ii) Explain why the organic compound shown in Fig. 5.1 is not a hydrocarbon. … … [1] (b) Fig. 5.2 is a diagram of the chemical structure of ethene. H H C C H H Fig. 5.2 (i) Name the group of hydrocarbons to which ethene belongs. … [1] (ii) Complete the symbol equation for the complete combustion of ethene in the presence of oxygen. C2H4 + … O2 … CO2 + … H2O [1] (iii) Complete the sentences about poly(ethene) using one word in each gap. Poly(ethene) is a polymer made from ethene. Polymers are large molecules built up from many smaller molecules called … . The formation of poly(ethene) is an example of … polymerisation. [2] [Total: 6]

6 marks

Mark scheme: 5(a)(i) C5H11Cl ; 1 5(a)(ii) any one from: 1 hydrocarbons contain carbon and hydrogen only ; (this compound) contains chlorine ; 5(b)(i) alkene ; 1 5(b)(iii) C2H4 + 3O2 → 2CO2 + 2H2O ; 1 5(b)(iii) monomers ; 2 addition ;

This question in 0653/32 Oct/Nov 2025

5 (a) Fig. 5.1 shows an organic compound. H H H Cl H H C C C C C H H H H H H Fig. 5.1 (i) Deduce the molecular formula of the organic compound shown in Fig. 5.1. … [1] (ii) Explain why the organic compound shown in Fig. 5.1 is not a hydrocarbon. … … [1] (b) Fig. 5.2 is a diagram of the chemical structure of ethene. H H C C H H Fig. 5.2 (i) Name the group of hydrocarbons to which ethene belongs. … [1] (ii) Complete the symbol equation for the complete combustion of ethene in the presence of oxygen. C2H4 + … O2 … CO2 + … H2O [1] (iii) Complete the sentences about poly(ethene) using one word in each gap. Poly(ethene) is a polymer made from ethene. Polymers are large molecules built up from many smaller molecules called … . The formation of poly(ethene) is an example of … polymerisation. [2] [Total: 6]

6 marks

Mark scheme: 5(a)(i) C5H11Cl ; 1 5(a)(ii) any one from: 1 hydrocarbons contain carbon and hydrogen only ; (this compound) contains chlorine ; 5(b)(i) alkene ; 1 5(b)(iii) C2H4 + 3O2 → 2CO2 + 2H2O ; 1 5(b)(iii) monomers ; 2 addition ;

This question in 0653/33 Oct/Nov 2025