AQA AS CHEMISTRY 7404/2 Paper 2 Organic and Physical Chemistry Question Paper + Mark scheme [MERGED] June 2022 *JUN* IB/M/Jun22/E7 7404/2 For Examiner’s Use Question Mark 1

AQA AS CHEMISTRY 7404/2 Paper 2 Organic and Physical Chemistry Question Paper + Mark scheme [MERGED] June 2022 *JUN* IB/M/Jun22/E7 7404/2 For Examiner’s Use Question Mark 1 2 3 4 5 6 7 Section B TOTAL Time allowed: 1 hour 30 minutes Materials For this paper you must have: • the Periodic Table/Data Sheet, provided as an insert (enclosed) • a ruler with millimetre measurements • a scientific calculator, which you are expected to use where appropriate. Instructions • Use black ink or black ball-point pen. • Fill in the boxes at the top of this page. • Answer all questions. • You must answer the questions in the spaces provided. Do not write outside the box around each page or on blank pages. • If you need extra space for your answer(s), use the lined pages at the end of this book. Write the question number against your answer(s). • All working must be shown. • Do all rough work in this book. Cross through any work you do not want to be marked. Information • The marks for questions are shown in brackets. • The maximum mark for this paper is 80. Advice You are advised to spend about 65 minutes on Section A and 25 minutes on Section B. Please write clearly in block capitals. Centre number Candidate number Surname Forename(s) Candidate signature I declare this is my own work. AS CHEMISTRY Paper 2 Organic and Physical Chemistry 2 *02* IB/M/Jun22/7404/2 Do not write outside the Section A box Answer all questions in this section. 0 1 This question is about rates of reaction. Potassium manganate(VII), KMnO4, reacts with sodium ethanedioate, Na2C2O4, in the presence of dilute sulfuric acid. 2 MnO4 –(aq) + 16H+(aq) + 5C2O4 2–(aq) → 2 Mn2+(aq) + 8H2O(l) + 10CO2(g) The reaction mixture is purple at the start and goes colourless when all the MnO4 –(aq) ions have reacted. The rate of reaction can be measured as 1000 t where t = the time taken for the mixture to go colourless. A student investigated how long it takes for this reaction mixture to go colourless at different temperatures. The same concentrations and volumes of each reagent were used in an experiment at each temperature. Table 1 shows the results. Table 1 Temperature / C Time t / s 1000 t 6.45 11.8 20.0 45.5 0 1 . 1 Complete Table 1. [1 mark] 0 1 . 2 State the independent variable in this investigation. [1 mark] 0 1 . 3 The student noticed that the temperature of each reaction mixture decreased during each experiment. Suggest how the student calculated the temperature values in Table 1. [1 mark] 3 *03* Turn over ► IB/M/Jun22/7404/2 Do not write outside the box Use the data in Table 1 to plot a graph of 1000 t against temperature. [3 marks] 0 1 . 4 0 1 . 5 Use your graph in Question 01.4 to find the time taken for the mixture to go colourless at 60 °C Show your working. [1 mark] Time t s 4 *04* IB/M/Jun22/7404/2 Do not write outside the box 0 1 . 6 The investigation shows that increasing the temperature causes the rate of reaction to increase. Explain why a small increase in temperature causes a large increase in the rate of reaction. [2 marks] 9 5 *05* Turn over ► IB/M/Jun22/7404/2 Do not write outside the Turn over for the next question box DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED 6 *06* IB/M/Jun22/7404/2 Do not write outside the box 0 2 A student has samples of these four compounds but does not know which is which: • butanoic acid • 2-methylpropanal • 2-methylpropanoic acid • 2-methylpropan-1-ol Step 1: Two of these compounds can be identified by simple chemical tests. Step 2: The other two compounds, that contain the same functional group as each other, can then be distinguished using a spectroscopic technique. Describe how these two steps could be used to identify which compound is which. [6 marks] 7 *07* Turn over ► IB/M/Jun22/7404/2 Do not write outside the box 6 8 *08* IB/M/Jun22/7404/2 Do not write outside the 0 3 box This question is about isomers. Hex-2-ene has the molecular formula C6H12 0 3 . 1 Draw the displayed formula of a position isomer of hex-2-ene that exists as E and Z isomers. [1 mark] 0 3 . 2 Draw the displayed formula of a chain isomer of hex-2-ene that does not exist as E and Z isomers. [1 mark] Butanal has the molecular formula C4H8O 0 3 . 3 Draw the skeletal formula of a functional group isomer of butanal that has an absorption in the range 1680–1750 cm–1 in its infrared spectrum. [1 mark] 9 *09* Turn over ► IB/M/Jun22/7404/2 Do not write outside the 0 3 box . 4 Draw the skeletal formula of a structural isomer of butanal that has an absorption in the range 3230–3550 cm–1 in its infrared spectrum. [1 mark] 0 3 . 5 Several saturated halogenoalkanes contain 17.8% carbon, 3.0% hydrogen and 79.2% bromine by mass. Calculate the empirical formula of these compounds. Give the IUPAC names of two saturated halogenoalkanes that have this empirical formula. [4 marks] Empirical formula Names of halogenoalkanes 1 2 8 10 *10* IB/M/Jun22/7404/2 Do not write outside the box 0 4 This question is about gas volumes. 0 4 . 1 TNT (C7H5N3O6) is an explosive because it can decompose very quickly and exothermically to form a large volume of gas. An equation for this decomposition is 2C7H5N3O6(s) → 3N2(g) + 5H2(g) + 12CO(g) + 2C(s) Calculate the volume of gas, in m3, measured at 1250 °C and Pa, produced by the decomposition of 1.00 kg of TNT (Mr = 227.0). The gas constant, R = 8.31 J mol–1 K–1 [5 marks] Volume of gas m3 11 *11* Turn over ► IB/M/Jun22/7404/2 Do not write outside the box 0 4 . 2 Alkenes have the general formula CnH2n When alkenes undergo complete combustion, 1.0 mol of CnH2n reacts with 3n 2 mol of oxygen. Calculate the volume of oxygen needed for the complete combustion of 200 cm3 of but-1-ene. The volumes of all gases are measured at the same temperature and pressure. [1 mark] Volume of oxygen cm3 0 4 . 3 Alkanes have the general formula CnH2n+2 Alkanes undergo complete combustion in a plentiful supply of oxygen. CnH2n+2 + xO2 → nCO2 + (n+1)H2O Determine x in terms of n [1 mark] x Turn over for the next question 7 12 *12* IB/M/Jun22/7404/2 Do not write outside the box 0 5 This question is about the synthesis of propylamine (CH3CH2CH2NH2) by the reaction of 1-iodopropane (CH3CH2CH2I) with an excess of ammonia. CH3CH2CH2I + 2NH3 → CH3CH2CH2NH2 + NH4I 0 5 . 1 Name and outline the mechanism for this reaction. [5 marks] Name of mechanism Outline of mechanism 13 *13* Turn over ► IB/M/Jun22/7404/2 Do not write outside the box 0 5 . 2 1-iodopropane is a liquid at room temperature. Calculate the number of molecules in 5.0 cm3 of 1-iodopropane (Mr = 169.9). Give your answer in standard form. For 1-iodopropane, density = 1.75 g cm–3 The Avogadro constant, L = 6.022 x 1023 mol–1 [2 marks] Number of molecules 0 5 . 3 In an experiment, 10.3 g of 1-iodopropane (Mr = 169.9) are reacted with an excess of ammonia. 2.3 g of propylamine (Mr = 59.0) are produced. Calculate the percentage yield in this experiment. [2 marks] Percentage yield 9 14 *14* IB/M/Jun22/7404/2 Do not write outside the box 0 6 Trichlorofluoromethane (CCl3F) was developed as a refrigerant. The production and use of CCl3F is now restricted. 0 6 . 1 The equation for a process used to manufacture CCl3F is SbF3Br2 + CCl4 → CCl3F + SbF2Br2Cl Calculate the percentage atom economy for the production of CCl3F in this reaction. Give your answer to 3 significant figures. [2 marks] Percentage atom economy An alternative synthesis of CCl3F is the free-radical substitution reaction between fluoromethane (CH3F) and chlorine. 0 6 . 2 An intermediate in this alternative synthesis is dichlorofluoromethane (CHCl2F) Give equations to represent the two propagation steps in the conversion of CHCl2F into CCl3F [2 marks] Propagation step 1 Propagation step 2 15 *15* Turn over ► IB/M/Jun22/7404/2 Do not write outside the box 0 6 . 3 Analysis of the products of this reaction shows the formation of a compound with the empirical formula CCl2F Give an equation to represent a termination step forming this compound. Show the structural formula of the product in the equation. [1 mark] Turn over for the next question 5 16 *16* IB/M/Jun22/7404/2 Do not write outside the box 0 7 In Europe, some of the glucose from crops is fermented to produce ethanol. Use of a carbon-neutral fuel leads to no net emissions of carbon dioxide to the atmosphere. 0 7 . 1 The ethanol produced by fermentation of glucose may be regarded as a carbon-neutral fuel. Justify this statement. Include the relevant chemical equations in your answer. [4 marks] Coffee beans from South America are exported to Europe in an outer layer called silverskin. The waste silverskin can be fermented to produce a solution containing propanone, ethanol and butan-1-ol. 0 7 . 2 Suggest why ethanol produced in Europe using silverskin from South America is less likely to be carbon-neutral than ethanol produced from crops grown in Europe. [1 mark] 17 *17* Turn over ► IB/M/Jun22/7404/2 Do not write outside the box 0 7 . 3 Table 2 shows the enthalpies of combustion of the three fuels from the fermentation of silverskin. Table 2 Fuel Standard enthalpy of combustion / kJ mol–1 Energy released per mole of CO2 produced / kJ ethanol, C2H5OH(l) –1371 butan-1-ol, C4H9OH(l) –2673 propanone, C3H6O(l) –1786 One way to measure a fuel’s environmental impact is to measure the amount of energy released per mole of CO2 produced. Complete Table 2. Use your answers to deduce the fuel with the lowest environmental impact by this measure. [2 marks] Question 7 continues on the next page 18 *18* IB/M/Jun22/7404/2 Do not write outside the box 0 7 . 4 A student investigated the combustion of propanone (C3H6O) using calorimetry. A copper calorimeter containing water was heated by the complete combustion of some propanone. The student did not record the final temperature of the water. Table 3 shows the student’s results. Table 3 Mass of propanone burned / g 1.18 Mass of water / g 260 Initial temperature of water / °C 22.3 Final temperature of water / °C Not recorded Use the results in Table 3 to calculate a value for final temperature of the water in the experiment. Assume that no heat was lost in the experiment and that the heat capacity of the calorimeter is negligible. For propanone, enthalpy of combustion = –1786 kJ mol−1 For water, specific heat capacity = 4.18 J g−1 K−1 [4 marks] Final temperature of water °C 19 *19* Turn over ► IB/M/Jun22/7404/2 Do not write outside the box 0 7 . 5 Butan-1-ol can be added to petrol for cars. An equation for the complete combustion of gaseous butan-1-ol is shown. C4H9OH(g) + 6O2(g) → 4CO2(g) + 5H2O(g) ΔH = –2504 kJ mol–1 Table 4 shows some mean bond enthalpy data. Table 4 Bond C=O C–H C–O O–H O=O Mean bond enthalpy / kJ mol− 496 Use these data to calculate a value for the mean C–C bond enthalpy in gaseous butan-1-ol. [3 marks] C–C bond enthalpy kJ mol–1 Question 7 continues on the next page 20 *20* IB/M/Jun22/7404/2 Do not write outside the Butan box -1-ol can be manufactured by reacting steam with but-1-ene in the presence of the catalyst, concentrated sulfuric acid. In the first part of this process, but-1-ene reacts with concentrated sulfuric acid to form compounds W and X. Butan-1-ol is then made from compound W. 0 7 . 6 Name and outline a mechanism to show the conversion of but-1-ene into compound W in the first part of this process. [5 marks] Name of mechanism Outline of mechanism 21 *21* Turn over ► IB/M/Jun22/7404/2 Do not write outside the box 0 7 . 7 There is a very low yield of butan-1-ol from but-1-ene in this manufacturing process. Explain why. [2 marks] Turn over for Section B 21 22 *22* IB/M/Jun22/7404/2 Do not write outside the Section B box Answer all questions in this section. Only one answer per question is allowed. For each answer completely fill in the circle alongside the appropriate answer. CORRECT METHOD WRONG METHODS If you want to change your answer you must cross out your original answer as shown. If you wish to return to an answer previously crossed out, ring the answer you now wish to select as shown. You may do your working in the blank space around each question but this will not be marked. Do not use additional sheets for this working. 0 8 When hexadecane (C16H34) is heated to a high temperature, one molecule of hexadecane decomposes to form an alkane containing eight carbon atoms and two different unsaturated compounds. Which equation could represent this reaction? [1 mark] A C16H34 → C8H16 + C5H12 + C3H6 B C16H34 → C8H18 + C6H10 + C2H6 C C16H34 → C8H18 + 2C2H4 + C4H8 D C16H34 → C8H18 + C6H14 + C2H2 23 *23* Turn over ► IB/M/Jun22/7404/2 Do not write outside the box 0 9 The diagram shows a fractionating column used in the industrial fractional distillation of crude oil. Which statement is correct? [1 mark] A The most viscous product is fuel oil. B The boiling point of naphtha is higher than diesel oil. C Molecules in diesel oil are held together by hydrogen bonds. D Kerosene is a mixture of compounds. 1 0 Which statement about poly(ethene) is correct? [1 mark] A It has a lower relative molecular mass than ethene. B It has a lower density than ethene at standard temperature and pressure. C It has a higher melting point than ethene. D It decolourises bromine water. 24 *24* IB/M/Jun22/7404/2 Do not write outside the 1 1 box A polymer is formed from the monomer CH2=CHCN Which statement is not correct? [1 mark] A The monomer is propanenitrile. B The monomer is unsaturated. C The polymer is an addition polymer. D The polymer has the repeating unit 1 2 Which alcohol when dehydrated forms a mixture of alkenes? [1 mark] A propan-1-ol B propan-2-ol C pentan-1-ol D pentan-2-ol 1 3 Which compound has the highest boiling point? [1 mark] A CH3COCH2CH3 B CH3CH2CH2CH2OH C CH3CH2CH2CHO D CH3CH2CH2CH2CH3 25 *25* Turn over ► IB/M/Jun22/7404/2 Do not write outside the box 1 4 Which statement about molecules in a gas is correct? [1 mark] A At a fixed temperature they all move at the same speed. B At a fixed temperature their average kinetic energy is constant. C As temperature increases, there are more molecules with the most probable energy. D As temperature decreases, there are fewer molecules with the mean energy. 1 5 Which compound produces (CH3)2CHCOCH3 when oxidised? [1 mark] A 2-methylpropan-1-ol B 2,2-dimethylpropanol C 2-methylbutan-2-ol D 3-methylbutan-2-ol 1 6 Which reaction does not result in a change in the shape around a carbon atom? [1 mark] A chloromethane with aqueous sodium hydroxide B ethene with bromine C propane with excess oxygen D propan-1-ol with acidified potassium dichromate(VI) 26 *26* IB/M/Jun22/7404/2 Do not write outside the 1 7 Which compound has the same empirical formula and molecular formula? box [1 mark] A butane B but-1-ene C propane D propene Questions 18, 19 and 20 Methanol is made in this equilibrium reaction, using a catalyst. CO(g) + 2H2(g) ⇌ CH3OH(g) ΔH = – 91 kJ mol–1 1 8 The reaction reaches equilibrium in a container of fixed volume. Which is the expression for Kc for this equilibrium? [1 mark] A Kc = [CH3OH] [CO] + [H2]2 B Kc = [CH3OH] [CO] [H2]2 C Kc = [CO] + [H2] 2 [CH3OH] D Kc = [CO] [H2] 2 [CH3OH] 27 *27* Turn over ► IB/M/Jun22/7404/2 Do not write outside the 1 9 box 2.0 mol of carbon monoxide is mixed with 3.0 mol of hydrogen and allowed to reach equilibrium. The equilibrium mixture contains 0.6 mol of methanol. What is the total amount, in mol, of gas at equilibrium? [1 mark] A 3.2 B 3.8 C 4.4 D 5.0 2 0 Which change in condition will decrease the equilibrium yield of methanol? [1 mark] A Increase the amount of CO in the equilibrium mixture. B Increase the pressure. C Increase the surface area of the catalyst. D Increase the temperature. Turn over for the next question 28 *28* IB/M/Jun22/7404/2 Do not write outside the Questions 21 and 22 box When 2-bromobutane is warmed with potassium hydroxide solution, substitution and elimination reactions both occur. 2 1 Which of these compounds is not produced? [1 mark] A butan-1-ol B butan-2-ol C but-1-ene D E-but-2-ene 2 2 What is the role of the hydroxide ions in the elimination reaction? [1 mark] A base B catalyst C electrophile D nucleophile END OF QUESTIONS 15 29 *29* IB/M/Jun22/7404/2 Do not write outside the There are no questions printed on this page box DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED 30 *30* IB/M/Jun22/7404/2 Do not write outside the box Question number Additional page, if required. Write the question numbers in the left-hand margin. 31 *31* IB/M/Jun22/7404/2 Do not write outside the box Question number Additional pag