oc.# CHEMISTRY Chains and Rings

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1 oc.# RECOGNISING ACIEVEMENT OXFORD CAMBRIDGE AND RSA EXAMINATIONS Advanced Subsidiary GCE CEMISTRY Chains and Rings Friday 9 JANUARY 2OO4 Morning 2812 t hour Candidates answer on the question paper. Additional materials: Data Sheet for Chemistry Scientificalculator Candidate Name Centre Number Candidate Number TIME t hour INSTRUCTIONS TO CANDIDATES o Write your name in the space above.. Write your Centre number and Candidate number in the boxes above.. Answer all the questions.. Write your answers in the spaces provided on the question paper.. Read each question carefully and make sure you know what you have to do be{ore starting your answer. INFORMATION FOR CANDIDATES. The number of marks is given in brackets [ ] at the end of each question or part question.. You will be awarded marks for the quality of written communication where this is indicated in the question.. You may use a scientific calculator. o You may use the Data Sheet for Chemistry.. You are advised to show all the steps in any calculations. FOR EXAMINER'S USE Question Number Max. Mark 3 I 4 I 5 12 TOTAL 60 This question paper consists of 10 printed pages and 2 blank pages. sp (SLM/GR) /4 o ocr 2oo4 [Tt1ool3424) Registered Charity Number: [Turn over

2 2 Answer all the questions. Examinefs Use (a) Alkenes are unsaturated hydrocarbons. The structures of but-1-ene and methylpropene are shown below. T \ l.. \/ *-rbd i '-\ " / \ / Y d i b:c F:C. b) t T " t but-1-ene methylpropene (i) what is meant by the terms unsaturated and hydrocarbon? (ii) unsaturated.. hydrocarbon ""121 suggest varues for the bond angre a in but-1-ene and the bond angle b in methylpropene. angle a angle b (iii) Explain, with the aid of a sketch, how p-orbitals are involved in the formation of the C:C double bond. t2l

3 (b) Alkenes undergo electrophilic addition reactions to form saturated compounds. 3 Examine/s I.Jtr (i) Define the term electrophile...t11 (ii) The reaction between bromine and methylpropene is an electrophilic addition. Describe, with the aid of curly arrows, the mechanism for this reaction. Show the intermediate and the product along with any relevant dipoles and lone pairs of electrons. C. t" n./.c/ \c'/" \ l - B r IBr intermediate p rod uct t4l (c) Polymer A, shown below, can be formed from an alkene. co^ C,. Cru T?25 T l - " l l - " l l r r l t l l l l l l l polymer A (i) State the type of polymerisation involved in the formation of polymer A....t1 l (ii) Draw a circle around the repeat unit of polymer A. (iii) ldentify the monomer that formed polymer A. (iv) Name polymer A....t1 l [Total: 15] [Turn over

4 Butan-1 -ol, C.C.C2C2O, reacts with sodium. (a) (i) State what you would see when butan-1-ol reacts with sodium. 4..t11 Examinef s Use (ii) Sodium butoxide is formed in this reaction. Write the formula of sodium butoxide...t1 l (iii) There are four structural isomers of Co.,oO that are alcohols. One of the isomers has been drawn for You. Complete the table below to show the other structural isomers. l l l l -C- C-C-C- l l l l O butan-1-ol isomer 1 isomer 2 isomer 3 (b) Butan-1-ol is oxidised by an acidified solution of potassium dichromate(vl) to form a carboxylic acid. (i) State the colour change that you would see. Colour changes from to (ii) Write a balanced equation for this oxidation of butan-1-ol to form a carboxylic acid. Use [O] to representhe oxidising agent. (iii) ldentify which of the isomers, 1, 2 or 3, in (axiii) could also be oxidised to form a carboxylic acid. isomer t3l..t Jan04

5 (c) Butan-1-ol reacts with hot concentrated sulphuric acid to form compound B. 5 Examine/s Use (i) Compound B has an empirical formula of C, and a relative molecular mass of 56. Use this information to deduce the moleculai formula of compound B. Show your working. (ii) Write a balanced equation to show the conversion of butan-1-ol into compound B. (iii) One of the isomers, 1, 2 or 3, in (axiii) also reacts with hot concentrated sulphuric acid to form compound B. ldentify which isomer. isomer (d) The ester, C3COOC.C2C2C., was formed by reacting ethanoic acid with butan-1-ol. l2l.t1 l o catalyst. I Ar. A., A, i Ar.,^\r I 3C-C' + C3C2C2C2-O - / 3C- C\ o + 2O \ O o- c2czc2c3 butan-l-ol ester Mr = 116 (i) State a catalyst for this reaction....t11 (ii) In an experiment, 6.96g of the ester was produced from 0.100mo of butan-1-ol. Calculate the number of moles of ester produced. (iii) Calculate the percentage yield. [Total: 1 6] 2812 Jan04 [Turn over

6 6 citronellol, c.,oroo,occurs naturally in both rose and geranium oils. The structural and skeletal tormul-ae of citronellol are shown below. Examinefs Use.i C" C. l " l -zc\..c\ -.i /\^/c\ -c, structural formula c, o skeletal formula (a) Name the two functional groups present in citronellol' and. """t21 (b) The functional groups in citronellol can be identified either by chemical tests or by infrared spectroscopy. (i) state which of the two functional groups you named in (a) is: 1 identified when bromine is added to citronellol, 2 more easily identified from the infra-red spectrum' (ii) State what you would see when bromine is added to citronellol. """"t11...t11 (iii) Draw the skeletal formula of the organic product formed when bromine is added to citronellol.

7 7 (iv) The infra-red spectrum of citronellol is shown below. Mark on this spectrum, with the letter X, the absorption that confirms the presence of the functional group that is most easily identified from this spectrum. Examinels Use o c (g '= c U) c (U 50 wavenumber lcm-1 (c) Reaction of a sample of citronellol, C1o20O, with hydrogen in the presence of a catalyst results in the formation of a saturated compound C. (i) Suggest a catalyst for this reaction. (ii) Determine the molecular formula of the saturated compound C. (iii) Construct a balanced equation for this reaction...t11..t l [Total: 9] [Turn over

8 8 alogenoalkanes are useful synthetic reagents for the preparation of many chemicals. Three reactions of 1,2-dichloroethane are shown below. important Examinels Use O - t t l t C- C-O, reaction 1 t t l l ct- c- c-ct c t reaction 2 \ / ' A - A /u--\ / \ compound D (a) The reagent and condition used in reactions 1 and 2 are the same, but the solvents are different. (i) State the reagent for reactions I and 2. (ii) State the condition for reactions 1 and 2. (iii) State the solvent for reaction 1. (iv) State the sofvent for reaction 2. (v) What type of reaction is reaction 1? (vi) What type of reaction is reaction 2?...t11,..t11..t11..t11..t1 l.t1 l (b) Draw the structure of compound D, formed in reaction 3. (c) Compound E, under the same condition as reaction 2, reacts to form a hydrocarbon with emplrical formula C. Suggest the identity of this hydrocarbon by drawing the displayed formula. [Total: 8]

9 5 (a) Write an equation for the combustion of ethanol. (b) In this question, one mark is available for the quality of written communication. 9.l2l Examinef s Use Describe, with the aid of equations, the industrial manufacture of ethanol from glucose, Cu.,rOu, and from ethene, Cro.Name each type of reaction and state all essential conditions. Future supplies of ethanol are likely to come from glucose rather than from ethene. Explain why. END OF QUESTION PAPER 2812 JanO4...tel Quality of Written Communication [1] [Total: 12]

10 Final Mark Scheme 2812 January 2004 I (a) (r) unsaturated contains a double/multiple/n bond hydrocarbon contains hydrogen and carbon onll'. Itt Itt (ii) angle a l0 o anslebllt-120n Itt (iii) Diagram to show a minimum of and p-orbitals 2 carbons, each with a o-bond / Overlap of adjacent p-orbitals (in u'ords or in diagraml / l2l (b) (i) electrophile: lone pair (of electrons) acceptor. (ii) '/ [tl C. r " rc'f"r-' - C I -C '7 I ^" { *?tu* G,.u- \,r,.- Intermediate Y- Br?t. T - rc A,. I,. product essential mark intermediate carbocation/carbonium ion. essential mark product accept primarv/"triangular"l curl.v affow. from double bond to Brz curly arrow showing movement of electrons in the Br-Br bond or the dipole in the Br-Br curly arro\\r from lone pair of electrons in Br to intermediate mark anlt errot"s first 5 tnax - l4l

11 Final Mark Scheme 2812 January (c) (i) Addition (not additional) ( ii) c2c3?*,r*.t T*'t*. T C-C C- I I, l i l./ (i ii) C3C2, \ /.C-C, / \ or but- 1-ene ( ir') Polv(but- I -ene) ITc

12 Final Mark Scheme 2812 January (a) (i) bubbles/ effervescence (ii) C:C:CzC2ONa*/C+qO- I\a" need not be shown as ionic Must clearll' show that the Na is bonded to the O, penalise if the Na-O is a covalent bond (iii) t t t l -C-C-C-C- t t t t O C. t t - l _c_ t t t O C. t t " t -c- t t l O r/ t3l (b) (i) orange to green/dark green/brown/black (ii)c+qo/ clroo + 2lol -+ c:zcoo + zo I mark available,for correct formula of the carboxylic acid l2l (iii)ldentify isomer 2-methylpropan-1-ol by appropriate number/name/formula r/ (c) (i) C2 has mass = 14, 14 x4 =56.'. C+a '/ '/ (ii)c"leo -+ C+s + zo (i i i ) I denti fy butan -2- ol by appropriate number/name/formula (d) (i) rsol (ii) 0.06 (iii)607' '/ '/ '/ trl ltotal : 161

13 - Final Mark Scheme 2812 January (a) (i) alkene al cohol/hydroxy/hydroxyl./ (b) (i) I : alkene & II : alcohol... both are needed l1l (ii) decolourised / colourless (iii) (iv)x as shown below l1l ftl T,A, I Vil 1 \/],W (c) (i) NiiPVRh/Pd tl l (ii)compound B is Croz:O (iii)cro:oo + : -) CroFIzzO [Total: 9]

14 -F I i Final Mark Scheme 2812 January 20A4 1. (i) sodium hydroxide/potassium hydroxidenao/ko (ii) heat to reflux (iii) water/aqueous accept NaO(aq) (iv) ethanol/ethanol iclalcohol accept NaO (alc) l1l (v) (nucleophilic) substitution/hydrolysis (vi)elimination 11l (b) t l,n-?-?-*n' (c) -C=C- [Total :8]

15 ITota Final Mark Scheme 2812 January 200 \ ia) CzsO + 3Oz --> 2COz + 3zO 2CO2 + 32O gets 1 mark (b) Fermentation CorzOo -> 2CzsO + 2COz Yeast lenzyme / temperature about 30 oc/ batch process vdration of ethene. Cz+ + zo -+ CzsO Temp > 100 oc/ Press atm continuous process I 6-20 MPa/phosphoric acid catalyst/./ Glucose is obtained from Plants Ethene is obtained from crude oil/cracking/fossil fuel glucose is renewable/ethene isn't./ I mark available for Quality of v,ritten commltnication... base the award of the mark on the abil communicate the essential chemistry by correct use of at least two from: fermentation/hyd ratioril catalyst/renewable/sustainable/biofu ellenzymes/finite/cracking '/