DHS Prelim P2 QP

This question paper consists of 15 printed pages and 1 blank page. © DHS 2014 [Turn over Name: Index Number: Class: DUNMAN HIGH SCHOOL Preliminary Examination 2014 Year 6 H2 CHEMISTRY 9647/02 Paper 2 Structured 16 September 2014 2 hours Additional Materials: Data Booklet INSTRUCTIONS TO CANDIDATES 1 Write your name, index number and class on this cover page. 2 Answer all questions. 3 Write your answers in the spaces provided on the question paper. 4 A Data Booklet is provided. 5 The number of marks is given in brackets [ ] at the end of each question or part question. 6 You may use a calculator. Question No. 1 2 3 4 5 6 Total % Marks 12 9 15 9 12 15 [72]

© DH 1 Pl a A pre co the me nu or Ad 1. 2. 3. (a ) (b ) S 2014 anning (P) student w epared by m ombustion o e enthalpy etal calori m umber of jou one degree dditional info Specific ca The maxim A temperat ) Constru with sta ……… … ) Identify error in Error ……… … ……… … Improve ……… … ……… … spirit bu Ans as provid e mixing equi of this ‘fuel m change of meter using ules of heat e Celsius. ormation: apacity of wa mum capacit ture rise of uct a balan ate symbols … ………… … one possib the experim … ………… … … ………… … ement … ………… … … ………… … urner contain the fuel mixt wer all que d with a s imolar amo mixture’ is  combustio the appa r needed to ater is 4.2 J ty of the me 5 C is cons ced equati o . … ………… … ble source o ment. … ………… … … ………… … … ………… … … ………… … ning ture 2 9647/02 estions in th spirit burn e unts of pe n 11.8 kJ pe n of this ‘f u ratus show n raise the te J g1 K1. etal calorime sidered to b on for the …………… of error and …………… …………… …………… …………… e spaces pr er containi n ntane and e er mole of ‘f uel mixture n below. H emperature eter is betw be significan complete c ………… … suggest an ………… … ………… … ………… … ………… … rovided. ng a ‘fuel ethanol. The fuel mixture ’ to find th e Heat capaci of the calor ween 100 to nt for this ex combustion ………… … n improvem ………… … ………… … ………… … ………… … metal c [T mixture’ w e enthalpy c e’. He was t e heat ca p ty is defin e rimeter by o 150 cm3. xperiment. of the ‘fue … ………… … ment to over … ………… … … ………… … … ………… … … ………… … calorimeter urn Over which was change of old to use acity of a ed as the one Kelvin el mixture’ … ………… [1] rcome this … ………… … ………… … ………… … ………… [2]

3 © DHS 2014 9647/02 [Turn Over (c) Calculate the minimum mass of the fuel mixture required to bring about a 5 C temperature rise. [2] (d) Write a plan to determine the heat capacity of the metal calorimeter using the apparatus provided. In your plan you should give details of the procedure (number your steps) and provide a table to record the readings to be taken, including the units. Details about the appropriate mass of water and fuel used, and temperature rise should also be included. You do not need to describe the preparation of the fuel mixture. ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… …………………………………………………………………………………………………

4 © DHS 2014 9647/02 [Turn Over Table: [4] (e) Show how you would calculate, from your above proposed plan and experimental results, the heat capacity of the metal calorimeter. [3] [Total: 12]

5 © DHS 2014 9647/02 [Turn Over 2 But–1–ene can be converted to compound E via the following series of reactions. CH2=CHCH2CH3 I A (C4H10O) II B C (C 5H9NO) D IV LiAlH4,dry ether V ClCOCH2COCl E (C8H13NO3) HCN, trace NaCN 10 - 20 °C Both compounds A and B produce a yellow precipitate on warming separately with aqueous alkaline iodine. (a) Iodine undergoes a disproportionation reaction with hot dilute NaOH(aq). Describe what is observed and write a balanced equation for the reaction. ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… [1] (b) State the reagents and conditions for steps I and II. Step I: ……………………………………… Step II: ……………………………………… [2] (c) In the boxes below, draw the structural formulae of compounds A, B, D and E. A B D E [4]

6 © DHS 2014 9647/02 [Turn Over (d) Explain why the reaction in Step III produces an equimolar mixture of two stereoisomers of compound C. ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… ………………………………………………………………………………………………… [2] [Total: 9] 3 2–chloroethyl methyl sulfide may be synthesised from ethane. CH2 CH2 CC H H Cl H H OH I Cl2(aq) II CH3SNa ethanol, heat CC H H S H H OH CH3 III CC H H S H H Cl CH3 2-chloroethyl methyl sulfide (a) Describe a simple chemical test to distinguish between CH 3SCH2CH2OH and CH3SCH2CH2Cl, of the reaction in Step III, stating the expected observation for each compound. Test: …………………………………………………………………………………………. ………………………………………………………………………………………………… Observation: ………………………………………………………………………………… ………………………………………………………………………………………………… [2]

7 © DHS 2014 9647/02 [Turn Over (b) The kinetics of the reaction in Step II was studied. The experimental results are given in the table below. Run [CH 3SNa] / mol dm–3 [CH2ClCH2OH] / mol dm–3 Relative rate / min–1 1 0.100 0.150 6 2 0.150 0.150 9 3 0.200 0.200 16 Use the data to determine the order of reaction with respect to both CH 3SNa and CH2ClCH2OH. Hence, write a rate equation for the reaction and state the units for the rate constant. Order of reaction with respect to CH3SNa: ……………………………………… Order of reaction with respect to CH2ClCH2OH: ……………………………………… Rate equation: ……………………………………… Units for rate constant: ……………………………………… [4] (c) In organic syntheses, the choice of solvent can affect the rate of a reaction. Ethanol is the solvent of choice in Step II above. The process of forming ion-dipole interactions between ions and solvent molecules is called solvation. Polar protic solvents such as ethanol, contains at least one hydrogen atom directly bonded to an electr onegative atom. These solvents solvate both cations and anions. It is known that the concentration of ions is inversely proportional to the degree of solvation of the ions involved. Polar aprotic solvents contain no hydrogen atom directly bonded to an electronegative atom. These solvents solvate cations well, but not anions. Dimethyl sulfoxide (DMSO) is an example of a polar aprotic solvent. S O CH3 CH3 DMSO

8 © DHS 2014 9647/02 [Turn Over (i) State the ion which acts as the nucleophile in the reaction in Step II. Nucleophile: ……………………………………… (ii) Suggest why DMSO does not solvate anions effectively. ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… (iii) With reference to your answers in (b) and (c)(ii), explain why the rate of reaction is 1000 times faster when the reaction in Step II is carried out in DMSO instead of ethanol. ………………………………………………………………………………………… …………………………………………