Partial preview of the text
Download Actual 2025 AQA AS CHEMISTRY 7404/2 Paper 2 Merged Question Paper + Mark Scheme + Insert and more Exams Chemistry in PDF only on Docsity!
Please write clearly in block capitals. Centre number Candidate number Surname Forename(s) Candidate signature AS CHEMISTRY Paper 2 Organic and Physical Chemistry | declare this is my own work. Tuesday 20 May 2025 Morning Time allowed: 1 hour 30 minutes Materials For this paper you must have: e the Periodic Table/Data Sheet, provided as an insert (enclosed) ¢ aruler with millimetre measurements Question Mark ¢ ascientific calculator, which you are expected to use where appropriate. For Examiner's Use 1 Instructions e Use black ink or black ball-point pen. Fill in the boxes at the top of this page. « Answer all questions. e 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 7 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 TOTAL want to be marked. ola} a} olr Section B Information e The marks for questions are shown in brackets. « The maximum mark for this paper is 80. Advice e You are advised to spend 65 minutes on Section A and 25 minutes on Section B. Jou 257404 01 "7404/2 IB/M/Jun25/G4002/V7 Do not write F outside the Section A box Answer all questions in this section. This question is about halogenoalkanes. [o[4].[1| Halogenoalkanes undergo substitution reactions with nucleophiles such as CN-, NH3 and OH- Explain why halogenoalkanes react with nucleophiles. [o[4].[2] 2-Bromobutane reacts with ammonia to form CHsCH(NH2)CH2CH3 Complete the mechanism for this reaction. [3 marks] 2-Bromobutane reacts with KOH to give a mixture of products. [0] 1].[3| Identify the solvent that should be used to ensure that butan-2-ol is the main organic product when 2-brombutane reacts with KOH Woden, ( H.d\ [1 mark] i ll | ll tyrionpapers.com 02 IB/M/Jun25/7404/2 Do not write outside the [o|1].[6| A co-ordinate bond is formed when the (CH3)3C* carbocation reacts with CN- to box form a nitrile. Explain how this co-ordinate bond is formed during this reaction. [2 marks] The CN ion denotr it lowe pom o cledbien On tae “Clot te the electra deyicia tk oreo Sy (C4s),C ~ Beth dich unr Cn -ordinoe, bend come feren. cr. 14 INI — 04 IB/M/Jun25/7404/2 Do not write outside the box Methanol can be made by the reaction of carbon monoxide with hydrogen. This reaction is done with a catalyst at a high temperature. [o[2].[1] Describe how a catalyst increases the rate of a reaction. [2 marks] [o[2].[2] Explain why the rate of a reaction increases as the temperature increases. [3 marks] [o[2].[3| Hydrogen bonds exist between molecules of liquid methanol. Draw a diagram to show a hydrogen bond between two molecules of methanol. Include all the lone pairs of electrons and the partial charges on the atoms involved in this hydrogen bond. [3 marks] ue Turn over > | ll ll l ll tyrionpapers.com 05 IB/M/Jun25/7404/2 ce CHO, Peles = has pale dip Quad Lender qa wiles cei ie CCly how mach NRenopl fyb atta tee CHO, wound A Cte thre , ine Snes ah requimd ond crags Iviqher Bieiling point: Turn over > | ll | ll ll tyrionpapers.com 07 IB/M/Jun25/7404/2 [o[4].[1] Compounds A and B ¢ each have the molecular formula C4HeO2 ¢ are functional group isomers of each other ¢ each react with sodium carbonate to form a gas. Compound A decolourises bromine water but compound B does not. Draw a possible structure of A and a possible structure of B. Compound A H ) l i] ne — ipo | H H H This question is about some compounds with the molecular formula C4HeO2 [2 marks] Compound B HH o vf YW os INN tyrionpapers.com IB/M/Jun25/7404/2 Do not write outside the box 10 10 There are no questions printed on this page DO NOT WRITE/ON THIS PAGE ANSWER IN THE/SPACES PROVIDED INIT tyrionpapers.com IB/M/Jun25/7404/2 Do not write outside the box 11 11 This question is about determining the relative molecular mass (M,) of different compounds. [o[5].[1] The M, of a compound can be determined by mass spectrometry. Propanone, prop-2-en-1-ol and butane each have M, = 58.0 Give the reason why high resolution mass spectrometry can distinguish between propanone and butane, but cannot distinguish between propanone and prop-2-en-1-ol. Proponene and butore hone di Mrbclan formulor, ro Drein exbce wares prey ane ppt one _howe [2 marks] Do not write outside the box Same welevlar proulo and Canrnat |be oiatinguined . Question 5 continues on the next page Turn over > IMI — a 1 IB/M/Jun25/7404/2 13 Do not write outside the 0) Calculate the M, of X. box Assume that the mass of air in the flask is the same in steps 2 and 7. Gas constant, R = 8.31 J K7 mol [5 marks] Y= wT -4 5 P = ie (ior 000) (2:72 x10 ) = (& 31) (a3) = O-d008GU md i ayes WL 0-761 = 5 mom SL t - [06-633 —\psa2 QS — M, 7 = ate! * a —— Turn over for the next question Turn over > IM — 13 IB/M/Jun25/7404/2 14 14 There are no questions printed on this page DO NOT WRITE/ON THIS PAGE ANSWER IN THE/SPACES PROVIDED INI tyrionpapers.com IB/M/Jun25/7404/2 Do not write outside the box 16 16 A student sets up the apparatus shown in Figure 2 to purify the cyclohexanol by distillation. Suitable clamps are used to hold the apparatus firmly in place. Figure 2 wee out Impure cyclohexanol + anti-bumping granules wet in veal from electric heater [o[6].[4| Explain why the condenser in Figure 2 is connected so that water enters at the bottom and not at the top. [2 marks] So thek Rs ful the 7 completly. and Moinkauin PM OD =Fere PVT uk | Ou poeek . This CWA eal tation : [o]6].[5| The flask heated in Figure 2 contains anti-bumping granules. State why these are used. [1 mark] Do not write outside the box To postuante ninbenk bens tng say sevuvypaliins OO Murpoee 1% venetty SbeaSe — peoeson INIA — 16 IB/M/Jun25/7404/2 17 17 [o[6].[6| Suggest why the flask in Figure 2 is heated with an electric heater, rather than a Bunsen burner. [1 mark] [o[6|.[7] State why the apparatus set up in Figure 2 is dangerous. State how this problem could be solved. [2 marks] Why the apparatus is dangerous Appsnslis AL sealed, Sa Do not write outside the box How to solve the problem dbs —— the —s ee to UX (OR) by rameiney te Ateppex ok the tip [o[6].[38| The cyclohexanol can be dehydrated to re-form cyclohexene by heating with concentrated phosphoric acid. Name the mechanism for this reaction. vec cotebandl’ edged, dB. [1 mark] Question 6 continues on the next page Turn over > | ll | ll ll tyrionpapers.com 17 IB/M/Jun25/7404/2 19 19 This question is about enthalpies of combustion. Define enthalpy change. [1 mark] [0/7 |.[2] The enthalpy of combustion of ethanol is -1371 kJ mol Asample of ethanol is burned completely in air to raise the temperature of 55.0 g of water by 46.2 °C Calculate the mass of ethanol in the sample. Assume there is no heat loss. Specific heat capacity of water, c= 4.18 JK" g" Heok abxercbed olen : =we AT “4 = 5S* 41% yx 462 = 106 KT [5 marks] wel. 3 ft: Sn v914 _ 10-Gl (error) enthalpy pA «STI rake, A 0-0077 wel M Ctra = abs XX wr. = O-0077 K46 0-356 5 —_ Mass of ethanol 0 356 g Question 7 continues on the next page tl Turn over > i} l l| ll tyrionpapers.com 19 IB/M/Jun25/7404/2 Do not write outside the box 20 20 An alkane burns completely in oxygen. The equation for this reaction is shown. 3n+1 CrHone2 + Oz > NCO, + (n+1)H2O0 Table 2 gives some mean bond enthalpies. Table 2 Bond C=O O-H Bond enthalpy / kJ molt 805 463 [o[7].[3] Use Table 2 to show that an expression for the sum of the bond enthalpies for all the bonds in the products is 2536n + 926 Coz thee ..C<0 2 an [1 mark] Ha0 hy DLO-H ws 2+) Tote othrole, = 9,( 805) + (2n+ 1} (463) = 2536n +928 [4] An expression for the sum of the bond enthalpies for all the bonds in the reactants is 1916n + 724 A calculated value for the enthalpy of combustion of an alkane is -3302 kJ mol Use this enthalpy change and the expressions to calculate a value of rn for this alkane. Use your value of n to deduce the molecular formula of the alkane. [3 marks] AH = bed bron - drowds —3302 = (Isten +724) - C5368 + 926) = —G20n-202 A leaner = Ge H a(S) +7 Value of n 5 as ic Molecular formula Cy H 2 Do not write outside the box 54a INA tyrionpapers.com IB/M/Jun25/7404/2 
