A-level CHEMISTRY Paper 2 Organic and Physical Chemistry 2 *02* IB/M/Jun22/7405/2

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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 buta... none 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. [Show More]

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