Chemistry > AQA Questions and Marking Scheme > AQA A-level CHEMISTRY 7405/2 Paper 2 Organic and Physical Chemistry Question Paper + Mark scheme [ME (All)
AQA A-level CHEMISTRY 7405/2 Paper 2 Organic and Physical Chemistry Question Paper + Mark scheme [MERGED] June 2022 *Jun227405201* IB/M/Jun22/E9 7405/2 For Examiner’s Use Question Mark 1 ... 2 3 4 5 6 7 8 9 10 TOTAL Time allowed: 2 hours Materials For this paper you must have: • the Periodic Table/Data Booklet, 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 105. Please write clearly in block capitals. Centre number Candidate number Surname Forename(s) Candidate signature I declare this is my own work. A-level CHEMISTRY Paper 2 Organic and Physical Chemistry 2 *02* IB/M/Jun22/7405/2 Do not write outside the Answer all questions in the spaces provided. box 0 1 An acidified solution of butanone reacts with iodine as shown. CH3CH2COCH3 + I2 → CH3CH2COCH2I + HI 0 1 . 1 Draw the displayed formula for CH3CH2COCH2I Give the name of CH3CH2COCH2I [2 marks] Displayed formula Name 3 *03* Turn over ► IB/M/Jun22/7405/2 Do not write outside the box 0 1 . 2 The rate equation for the reaction is rate = k[CH3CH2COCH3][H+] Table 1 shows the initial concentrations used in an experiment. Table 1 CH3CH2COCH3 I2 H+ Initial concentration / mol dm−3 4.35 0.00500 0.825 The initial rate of reaction in this experiment is 1.45×10−4 mol dm−3 s−1 Calculate the value of the rate constant, k, for the reaction and give its units. [3 marks] k Units 0 1 . 3 Calculate the initial rate of reaction when all of the initial concentrations are halved. [1 mark] Initial rate of reaction mol dm−3 s−1 Question 1 continues on the next page 4 *04* IB/M/Jun22/7405/2 Do not write outside the box 0 1 . 4 An experiment was done to measure the time, t, taken for a solution of iodine to react completely when added to an excess of an acidified solution of butanone. Suggest an observation used to judge when all the iodine had reacted. [1 mark] The experiment was repeated at different temperatures. Figure 1 shows how 1 t varied with temperature for these experiments. Figure 1 5 *05* Turn over ► IB/M/Jun22/7405/2 Do not write outside the box 0 1 . 5 Describe and explain the shape of the graph in Figure 1. [3 marks] 0 1 . 6 Deduce the time taken for the reaction at 35 oC [1 mark] Time s Question 1 continues on the next page 6 *06* IB/M/Jun22/7405/2 Do not write outside the box 0 1 . 7 For a different reaction, Table 2 shows the value of the rate constant at different temperatures. Table 2 Experiment Temperature / K Rate constant / s−1 1 T1 = 303 k1 = 1.55×10−5 2 T2 = 333 k2 = 1.70×10−4 This equation can be used to calculate the activation energy, Ea In � k1 k2 � = Ea R � 1 T2 – 1 T1 � Calculate the value, in kJ mol−1, of the activation energy, Ea The gas constant, R = 8.31 J K−1mol−1 [5 marks] Ea kJ mol–1 7 *07* Turn over ► IB/M/Jun22/7405/2 Do not write outside the box 0 1 . 8 Name and outline the mechanism for the reaction of butanone with KCN followed by dilute acid. [5 marks] Name of mechanism Outline of mechanism Turn over for the next question 21 8 *08* IB/M/Jun22/7405/2 Do not write outside the box 0 2 Tetrafluoroethene is made from chlorodifluoromethane in this reversible reaction. 2CHClF2(g) ⇌ C2F4(g) + 2HCl(g) ΔH = +128 kJ mol−1 A 2.00 mol sample of CHClF2 is placed in a container of volume 23.2 dm3 and heated. When equilibrium is reached, the mixture contains 0.270 mol of CHClF2 0 2 . 1 Calculate the amount, in moles, of C2F4 and of HCl in the equilibrium mixture. [2 marks] Amount of C2F4 mol Amount of HCl mol 0 2 . 2 Give an expression for Kc for this equilibrium. [1 mark] Kc 9 *09* Turn over ► IB/M/Jun22/7405/2 Do not write outside the box 0 2 . 3 Calculate a value for Kc Give its units. [3 marks] Kc Units 0 2 . 4 State and explain the effect of using a higher temperature on the equilibrium yield of tetrafluoroethene. [3 marks] Effect on yield Explanation Question 2 continues on the next page 10 *10* IB/M/Jun22/7405/2 Do not write outside the box 0 2 . 5 Chemists provided evidence that was used to support a ban on the use of chlorodifluoromethane as a refrigerant. Many refrigerators now use pentane as a refrigerant. State the environmental problem that chlorodifluoromethane can cause. Give one reason why pentane does not cause this problem. [2 marks] Environmental problem Reason why pentane does not cause this problem 11 11 *11* Turn over ► IB/M/Jun22/7405/2 Do not write outside the box 0 3 This question is about 2-methylbut-1-ene. 0 3 . 1 Name the mechanism for the reaction of 2-methylbut-1-ene with concentrated sulfuric acid. Outline the mechanism for this reaction to form the major product. [5 marks] Name of mechanism Outline of mechanism to form major product 0 3 . 2 Draw the structure of the minor product formed in the reaction in Question 03.1 Explain why this is the minor product. [3 marks] Structure of minor product Explanation 12 *12* IB/M/Jun22/7405/2 Do not write outside the box 0 3 . 3 Draw the skeletal formula of a functional group isomer of 2-methylbut-1-ene. [1 mark] 0 3 . 4 2-methylbut-1-ene can form a polymer. State the type of polymerisation. Draw the repeating unit for the polymer formed. [2 marks] Type of polymerisation Repeating unit 11 13 *13* Turn over ► IB/M/Jun22/7405/2 Do not write outside the box 0 4 Proteins are polymers made from amino acids. Part of the structure of a protein is shown. –Cys–Ser–Asp–Phe– Each amino acid in the protein is shown using the first three letters of its name. 0 4 . 1 Identify the type of protein structure shown. [1 mark] Tick () one box. Primary Secondary Tertiary 0 4 . 2 Draw a structure for the –Cys–Ser– section of the protein. Use the Data Booklet to help you answer this question. [2 marks] Question 4 continues on the next page 14 *14* IB/M/Jun22/7405/2 Do not write outside the box 0 4 . 3 Name the other substance formed when two amino acids react together to form part of a protein chain. [1 mark] The general structure of an amino acid is shown. R represents a group that varies between different amino acids. R groups can interact and contribute to protein structure. 0 4 . 4 Explain why the strength of the interaction between two cysteine R groups differs from the strength of the interaction between a serine R group and an aspartic acid R group. Use the Data Booklet to help you answer this question. [4 marks] 0 4 . 5 Deduce the type of interaction that occurs between a lysine R group and an aspartic acid R group. [1 mark] 9 15 *15* Turn over ► IB/M/Jun22/7405/2 Do not write outside the box 0 5 This question is about the preparation of hexan-2-ol. Hexan-2-ol does not mix with water and has a boiling point of 140 oC Hexan-2-ol can be prepared from hex-1-ene using this method. a Measure out 11.0 cm3 of hex-1-ene into a boiling tube in an ice bath. b Carefully add 5 cm3 of concentrated phosphoric acid to the hex-1-ene. c After 5 minutes add 10 cm3 of distilled water to the mixture and transfer the boiling tube contents to a separating funnel. d Shake the mixture and allow it to settle. e Discard the lower (aqueous) layer. f Add a fresh 10 cm3 sample of distilled water and repeat steps d and e. g Transfer the remaining liquid to a beaker. h Add 2 g of anhydrous magnesium sulfate and allow to stand for 5 minutes. i Filter the mixture under reduced pressure. j Distil the filtrate and collect the distillate that boils in the range 130–160 oC 0 5 . 1 It is important to wear eye protection and a lab coat when completing this experiment. Suggest, with a reason, one other appropriate safety precaution for this experiment. [2 marks] Precaution Reason 0 5 . 2 Give a reason for adding the distilled water in steps c and f. [1 mark] 0 5 . 3 Give a reason for adding anhydrous magnesium sulfate in step h. [1 mark] Question 5 continues on the next page 16 *16* IB/M/Jun22/7405/2 Do not write outside the box 0 5 . 4 Complete and label the diagram of the apparatus used to filter the mixture under reduced pressure in step i. [2 marks] 0 5 . 5 Identify the most likely organic impurity, other than hex-1-ene, in the distillate collected in step j. Suggest one reason why it could be difficult to remove this impurity. [2 marks] Impurity Reason 17 *17* Turn over ► IB/M/Jun22/7405/2 Do not write outside the box 0 5 . 6 Calculate the mass, in g, of hexan-2-ol formed from 11.0 cm3 of hex-1-ene if the yield is 31.0% Give your answer to 1 decimal place. Density of hex-1-ene = 0.678 g cm−3 [4 marks] Mass g 12 18 *18* IB/M/Jun22/7405/2 Do not write outside the box 0 6 This question is about compound X with the empirical formula C2H4O Figure 2 shows the infrared spectrum of X. Figure 3 shows the 13C NMR spectrum of X. The 1H NMR spectrum of X shows four peaks with different chemical shift values. Table 3 gives data for these peaks. Figure 2 Figure 3 Table 3 Chemical shift / ppm 3.9 3.7 2.1 1.2 Splitting pattern quartet singlet singlet doublet Integration value 1 1 3 3 19 *19* Turn over ► IB/M/Jun22/7405/2 Do not write outside the box Show how information from Figure 2, Figure 3 and Table 3 can be used to deduce the structure of compound X. [6 marks] The answer space for this question continues on the next page 20 *20* IB/M/Jun22/7405/2 Do not write outside the box 6 21 *21* Turn over ► IB/M/Jun22/7405/2 Do not write outside the box 0 7 This question is about esters. Figure 4 shows an incomplete mechanism for the reaction of an ester with aqueous sodium hydroxide. Figure 4 0 7 . 1 Add three curly arrows to complete the mechanism in Figure 4. [3 marks] 0 7 . 2 Name the type of reaction shown in Figure 4. [1 mark] 0 7 . 3 Deduce the role of the CH3O− ion in step 3 shown in Figure 4. [1 mark] 0 7 . 4 A triester in vegetable oil reacts with sodium hydroxide in a similar way. Give a use for a product of this reaction. [1 mark] 6 22 *22* IB/M/Jun22/7405/2 Do not write outside the box 0 8 Benzene reacts with methanoyl chloride (HCOCl) in the presence of a catalyst. 0 8 . 1 Give an equation for the overall reaction when benzene reacts with methanoyl chloride. Name the organic product. [2 marks] Equation Name 0 8 . 2 Identify the catalyst needed in this reaction. Give an equation to show how the catalyst is used to form the electrophile, [HCO]+ [2 marks] Catalyst Equation 0 8 . 3 Outline the mechanism for the reaction of benzene with the electrophile, [HCO]+ [3 marks] 7 23 *23* Turn over ► IB/M/Jun22/7405/2 Do not write outside the Turn over for the next question box DO NOT WRITE ON THIS PAGE ANSWER IN THE SPACES PROVIDED 24 *24* IB/M/Jun22/7405/2 Do not write outside the box 0 9 This question is about olive oil. A sample of olive oil is mainly the unsaturated fat Y mixed with a small amount of inert impurity. The structure of Y in the olive oil is shown. Y has the molecular formula C57H100O6 (Mr = 880). The amount of Y is found by measuring how much bromine water is decolourised by a sample of oil, using this method. • Transfer a weighed sample of oil to a 250 cm3 volumetric flask and make up to the mark with an inert organic solvent. • Titrate 25.0 cm3 samples of the olive oil solution with 0.025 mol dm−3 Br2(aq). 0 9 . 1 A suitable target titre for the titration is 30.0 cm3 of 0.025 mol dm−3 Br2(aq). Justify why a much smaller target titre would not be appropriate. Calculate the amount, in moles, of bromine in the target titre. [2 marks] Justification Amount of bromine mol 25 *25* Turn over ► IB/M/Jun22/7405/2 Do not write outside the box 0 9 . 2 Calculate a suitable mass of olive oil to transfer to the volumetric flask using your answer to Question 09.1 and the structure of Y. Assume that the olive oil contains 85% of Y by mass. (If you were unable to calculate the amount of bromine in the target titre, you should assume it is 6.25×10−4 mol. This is not the correct amount.) [5 marks] Mass of olive oil g Question 9 continues on the next page 26 *26* IB/M/Jun22/7405/2 Do not write outside the The olive oil solution can be prepared using this method. box • Place a weighing bottle on a balance and record the mass, in g, to 2 decimal places. • Add olive oil to the weighing bottle until a suitable mass has been added. • Record the mass of the weighing bottle and olive oil. • Pour the olive oil into a 250 cm3 volumetric flask. • Add organic solvent to the volumetric flask until it is made up to the mark. • Place a stopper in the flask and invert the flask several times. 0 9 . 3 Suggest an extra step to ensure that the mass of olive oil in the solution is recorded accurately. Justify your suggestion. [2 marks] Extra step Justification 0 9 . 4 State the reason for inverting the flask several times. [1 mark] 27 *27* Turn over ► IB/M/Jun22/7405/2 Do not write outside the box 0 9 . 5 A sample of the olive oil was dissolved in methanol and placed in a mass spectrometer. The sample was ionised using electrospray ionisation. Each molecule gained a hydrogen ion (H+) during ionisation. The spectrum showed a peak for an ion with m z = 345 formed from an impurity in the olive oil. The ion with m z = 345 was formed from a compound with the empirical formula C5H10O Deduce the molecular formula of this compound. [2 marks] Show your working. Molecular formula Turn over for the [Show More]
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