[uni@- Sirn
RAFFLES INSTITUTION Section A PRELIMINARY EXAMINATION 201 O For each question there are four possible answers, A, B, C, and O. Choose the one you Higher consider to be correct. 2 N. \milX6.rrrxro2' Which of the following particles particles g :)t rool I, stated contain an equal number of as 12 of GHEMISTRY 9647tol,9746tO1 A aqueous chloride ions in a solution containing 0.25 mol of the complex, B li# i"lll:',i;L?;" lfJ;;!., i3 f,"1,'i J, Ji H'n ro,xI' r x, Paper 1 Multiple Choice 27 September 2010 ]I i; m SI = r c oxygen atoms in 100 9 of"allactite, Mn7(AsO4)r(OH)8, of molar mass T9S g mol- - " " ' D oxygenatomsin22.4dm" of carbondioxidegasats.t.p. n^:1 IOO- Additional Materials: OMR Answer Sheet t hour rlrcrr\ " \-11ti/^''\X 16 = f rOO\ Data Booklet ho= *f*t D, Which of the following statements is correct?
READ THESE INSTRUCTIONS FIRST A The first ionisation energy of rubidium is higher than the first ionisation energy of calcium. Do not open this question booklet until you are told to do so. B The first ionisation energy increases from sodium to phosphorus as the number of protons increases but number of inner quantum shells remains the same. Write in soft pencil. The second ionisation energy of chromium is lower than the second ionisation Do not use staples, paper clips, highlighters, glue or correction fluid. enefgy of manganese as manganese has one more proton than chromium. Write your name, class and index number in the spaces provided on the Answer Sheet. D The semnd ionisation energy of any element is always higher than its first ionisation energy as more energy is required to remove an electron from an positive There are forty questions on this paper. Answer all questions. For each question there are four increasingly more species possible answers A, B, C and D. Choose the one you consider correct and record your choice in soft pencil on the separate A Answer Sheet. 3 The boiling points (b.p.) of ammonia, carbon dioxide and hydrogen chlor,de are given n below. Read the instructions on the Answer Sheet very carefully. gas formula b.o. / "C Each correct answer will score one mark. A mark will not be deducted for a wrono answer. ammonta NH: 33 Any rough working should be done in this booklet- carbon dioxide CO -78 hvdrooen chloride HC/
Which of the following statements is correct?
A NH3 has a higher b.p. than HC1 because the hydrogen bonding in NH3 is stronger than the permanent dipole-permanent dipole interactions in HC/. B CO2 has a higher b.p. than HC/ because the permanent dipole-permanent dipole interactions in CO2 are stronger than the permanent dipole-permanent dipole interactions in HC/. C The strength of the instantaneous qipole-induced dipole interactions Increases in the order HCi. CO,. NH,. ( dep. On nr. Ot e- -'(fFfqr {r N. ) D The strength of the permanent dipole-permanent dipole interactions increases in the order HC/ < co? < NH3 ,c\et. o{ ete$.€A ?" $ecfo"CAai;,riU + pJu.<$ crt nu\eu{q J
This document consists of 17 printed pages n . (rxrlb)*(gx+oo1 Qr\e.k tI-Jts'oe'-J p;x&F, Frr,ta\ =\- ,o rD ,/ -: in \orgt acess" = 36o LPa r&\e.k,'tr-J C5,Or'-1 2LA P' L R P^ z+.ro r/-\n2\+ \n 0t'-) ." P. = LPo. Y = o roo 5*' [' =fL5' a = t € i#: = *- - t,, - 6-'{ r - 9-lQ9- A4 At 298 K. two bulbs are connected qy a stopcock. The 2 dmr bulb is filled with oxygen at lodide ions react with peroxodisulfate ions to form iodine and sulfate ions r- s.O a pressure of 200 kPa and the 8 dm' bulb is filled with nitrogen at 400 kPa. The stopcock b, -J1 1 is then opened to allow the gases to mix at 348 K. 2l-(aq) + Sros'?laq) ) Ir(aq) + 2so41(aq) - 0.O> rrot dm-5-' pressure, The final total in kPa, of the system at 348 K is The above reaction is first order with respect to F and 5206'- ions respectively. In an experiment, 5.0 mol dm-3 Na2S2Os was reacted with 0.025 mol dm-3 KL The halt-life for 310 A 420 B 400 C 360 D this reaction was found to be 6.9 s. What is the rate constant. in mol-l dm3 s-1. of this reaction? A gaseous dimer, J2, dissociates into its gaseous monomer, at 400 K and 1 atm J, A 0.01 B 0.02 c 0.1 D 0.2 )s pressure. Dissociation is complete at 450 K. T: * >3 Which of the following graphs shows the variation of volume with temperature when one Substances X, Y and Z react according to the following equation: mole of J2 rs heated from 350 K to 500 K at a constant pressure of 1 atm? Assume that Qa gases 11 the behave ideally. (R = 0.082 dm3 atm K X(aq) + 2Y(aq) + Z(aq) ) 2w(aq) + U(aq) A+ 45OK, , r n=) mo\'.' CDcneet( i\,SstX.rohon. 800R 800R PV < oR-T txl E E (x. \50 ! p.y= >-r 0.10 i +oon | +oon y= 10oR 0.08 0.06
500 r/ K 0.04 o.o2
800R
E A rate = k[Y]'?[z] B rate = klxllYl[z] | +oon
9 Under extreme conditions, gallium chlorrde, Ga2C16 can be formed vta the dimerisation of s UdUlr s00 T/ K K 350 400 450 2GaCl3(S) + Garc16(g)
ln an experiment, a total pressure of 7.75 x 1Ot Pa was measured when a R 6 When 25 cm3 of 1.0 mol dmi sodium hydroxide rs neutralrsed wrth an equal volume of 3.745 x 10 " mol sample of GaCl3 was allowed to dimerise in a 1.80 dm3 vessel at v I oC. 1 .O mol dm hydrochloric acid, the temperature of the mixture rose by 6.8 200 "c. oC, What will be the temperature change, if x cm3 of 0.5 mol dm-3 sodium hydroxide is Calculate o, the fraction of GaC/3 that dimerised at 200 assuming ideal gas neutralised with an equal volume of 0.5 mol dm-'hydrochloric acid? behaviour. (Assume heat losses to be negligible in each case.) A 0.053 B 0.105 c 0.895 D 0.947 A 1.7 B 3.4 13.6 c 6.8 D A'mtxn\/mu\ 6e,cl rcuc\3 € e gv:nRI -rIb+)5)X4i:!_6:--E_ _ t.rDtr rnot-, o At\qcrt = =_ b-t \n,ha\ 3'1+, Xlt's -l-1b\rglx .Oqm ---TRx r.o lVvirne -)x-. +x- a \.gaxt0-3 x6'3)x +13 ) r- B-r. \'13 cno\-' b1rn" 3.-1+)X19"-1t { $: 3 5\qxtril5 rnu\ *51't r :_ 2:LX4,lx AT \* = 31't51\o-j ->atx- / rcx0-5\ -: IOOO R 3.1+5X \0-3 *a- \ lbcD / 3'14!2q1s--r * )L : ) 5+4 n'{,J AT = 3.rf :t r \'15qXl0-+ "..r*=*##l: lU' The graph below shows how the fraction of a substance, X represented by one ot the Aluminium and silicon are consecutive elements in Period 3 of the Periodic Table. A,O following compounds in the equilibrium mixture shown below varies with temperature at A'o Which statement concerning the compounds of aluminium *and silicon is incorrect? oressures of Y Pa and Z Pa. F\$,'- gAl s\C\q Pvt :- give ) A Both their chlorides strdngly'acidic solutions when added to water. . , _ \ 1 - 4NH3(g) + 3or(g) :2Nr(s; + OlzO(o) AH = -1267 kJ mol B Both their oxides give neutral solutions when added to water. ': bUtb inSSuB t L pH = t / points. C Both their oxides have high melting A\'05-g\ar* ioO,c ; :.tgr- g,qn\ f,,oVolhr 1 il\Dl D Both their chtorides are covatent. bt*t" ha.n_ :,- ' Fraction of X c \"hmIt,%X V s:i"gr" ,ro\eor6i- in equilibrium :\tn-\u{c . mixture / % =) ?r:E sh(b \etf (-0a'ur. The diagram shows ihe first ionisation energy of eight consecutive elements, P to W in e$o\hnr{Nl rXn) b'u the Periodic Table. Their atomic numbers lie between 3 and 20. r .'. \ q$ bq Nr or rl,O" t Qrn"\ 3 ZPa ' t .o*" f(c'.),% X is hgter{r.SPa &:,Qercur $ ?oE s[i(b coor q {o {hc \ofl vu .->' 6. z 9a '.' hqhr P (trnrrrg ldentify X and the correct relative magnitudes of Y and Z rxn V( tyd prr.lurL:' \usser iv X Pressure 0fc'.ufr\ ut gr,l A Nz Z>Y B Oz Y>Z c Hro \>z Which of the following statements is incorrect? D NH3 Z>Y A P forms an acidic oxide. r ^- ^^ ,.! . . - \ B R is skonsly,oxidising5lNqg\) cc{Ugqg -: \o:p- \LNql@ * t*oO$\trt\( I I Which of the following conjugate acid-base pairs can be used to prepare a buffer of c u ooes not orssotve tn waler .b" D W forms a hydride of general formula HzW. approximately pH 6 that has maximum buffer capacity? p\\.tKo - \rI s A NH4" / NH3 t'k 10 mo, dm' pH='g(i*;)=:u Which one of the following statements concerning the thermal decompositions of B HrCO3/ HCO3 ^;;' es=Aci*$d' C., anhydrous magnesium nitrate and anhydrous barium nitrate is incorrect? c H3PO4 / H2PO4 f: :l ii,?. = ? 33 I l3j,Ti",o;i, a'd D CH3COOH / CH3COO- rii"iCii.cbo =rlj",.i, 9H= -!(uro-h,'1=llls-=- a.\a ';;;i;' ' 1'3]X\U{/\: A Lattice energy of magnesium nitratq is .r!9re €xothermic than that of barium pH. -r5(gS nitrare \AR\o+b-W+ 3 B Nitrogen dioxide is evolved at a lower tempbiature from magnesium nitrate than 25 cm3 0.10 mol dm-3 of aqueous ammonia was added#r):"1"19 10 cm3 of 0.20 mol dm of to >xru-1\ from barium nitrate. C., hydrochloric acid. What is the pl solution? [-ii--=7-l The oxide from the barium nitrate is formed more readilv than that trom rheThe pK valuevarue forror aqueous ammonia is 4.75 9oA- pKrrtrq$$gHP = 4"15\\95, "'*:Ltt';"#ltins gb6sl [5]8,^;Tc+ masnesium nitrate : thcrrcU\ stObr\\ O t8 A key molecule in the chemistry of vision is the highly conjugated rhodopsin, which is ,U A chloroalkane W with molecular formula of C5H11C1 exhibits optical aciivity. Qn warming 't- O C =.-'". synthesised in the rod cells of the eye from 11-cls-retinal and a primary amine in the *C1 rOmXttbg {;f.,,na\e*wwith.alcohoricNaOH.twoalkenesXandYareformed,Xbeingthemajorproduct.qq;ntilrC\Scno'c. (gtt) protein opsin. '.' fsorc + sh'i.r\d o,>\:".n {oa., r p*f-tu*,a 3lini,],,'J,i ,,i'!1"X1"" ;: :1,:,i::fri"J" ?,ill'?ii",,1" Xll"i;: ::i:[,"fl,,f,$T'i# u'i followins could bew? ;t#S.t-R shagl1t a\* ; NH2-oPsln "t 3 3i:3ElJiB;3i:3il: S Sil:Sil'J.1,"J,:iT'* t*ll'u. "}r&J.-x ie-\'\ G:^I iti, Ln') =t1., uAl$+ opsin +lUO i-t r-1 H N H --+ \ -0H D" :^?11":lll""',:::l:l:T:::#lffi[?:::ilff:ffffiH3;,I,"::[iJf"::Hlry 1 1 -cls-retinal rhodo'sin \" akoho\ A The reaction is catalysed by a small amount of base. Which of the following statements is correct? B The slow step involves the formation of a C-C bond. C The Gibbs free energy of the reaction is positive at high temperatures. A 1 mole of 11-cls-retinal reacts with 5 moles of hydrogen gas. (6 rfO\) D The reaction between butanal and hydrogen cyanide is slower than the reaction B The reaction between '11-cliretinal and NH2-opsin is a condensation reaction. between butanone and hydrogen cyanrde. C The reaction of 11-cls-retinal with L|A1H4 produces a product is optically f fu\6f,\yg y\n5 \ ituq R q{ p *;Sb",c- h,tflilh? that " t active. =) r^fr i: :\u,rr.tf ) D The reaction between 11-cls-retinal with hot acidified potassium manganate(Vll) produces a total of five different organic products. Irts: \' lH' rd- ;15.h$-c 'c'-o \xo , A F\ 30 The structures of some amino acids are shown below glutamic acid H I H2N-C-COOH (?",), cooH lysrne u H2N C COOH (CHdr NHz The isoelectric point of asparfame is 5.9. Which of the following is the predominant phenylalanine present physiological pH species in an aqueous solution at 7 3? + O.\LO\\fh- A HO H .tl1 (ODd btw,nt: *(J0O- H3NCCNHCCOOCH3 - CH, CH: coo- tatl \-/ senne tl B HO H ltt H2N-C-COOH H2N C C NH-C-COO- I CH2OH CH?-t- CHT coocH"'t-z'-i -\ valtne H \",2il )l H2N-C-COOH C +ll HO H ,c.H H3N C-C-NH-C-COO cHi bs. CHr CHr coocH3 _\ IR Which of the following pairs of amino acids are likely to be found on the outside of a \dnphg\\\cAf olobular nrotein. and which on the inside? \--2t.lt G -tsdu.bLQ-) HO H -) oubtde on the outside on the inside (itnt- (vdtt0s Har.r-C-C-rH cooc". R A glutamic acid ano tysine bds) vatine and phenytatanine / qrP5 E valine and pnenylalaninelyjUU glutamic acid and lysine (,Od.c), { \GNP\rDb\c v \ ) , 9"' 't c serine and lysine (!\-!6) valine and glutamic acid (vdrJl '/ coo?"' €'.c\S\da D glutamic acid and valrne phenylalanine and serine lv$;' t.lt-\ ivAfJJ ) ) Section B The responses A to D should be selected on the basis of For each ofthe questions in thls section, one or more ofthe three numbered statements 1 to 3 A B c D may De correq. 1, 2 and 3 1 and2 2and3 1 only Decide whether each of the statements is or is not correct (you may find jt helpful to put a tick only are only afe is against the statements that you consider to be correct). correct correct correct correcl The responses A to D should be selected on the basis of No other combination of statements is used as a correct response Clote ar. os re{etR @ ) Astatine is an element in Group VIL Which of the following statements are correct? A B c D A" tn Ntl3Q) 1 2 and J 1 and2 z and 3 1 only 1 sitver astatide is insotubte in aqueous ammonia. {9a inF\ onty are only are is 2 Sodium astatide and hot concentrated sulfunc acid react to form astatine. correct correcr @rrect correct 3 Hydrogen astatide is less stable to heat than hydrogen iodide. 'j h-A.u bood is \s3cl- vo0fur. No other combination of statements js used as a correct response. + A stability constant rs an equilibrium constant for the formation of a complex in solution. R .',r ,S,.Sn;\1l"t#t\$ffiJs does the rirst species have a smarer bond ansre? S* (l)f) Consider the formatron ot INi(NH,)6]':-(aq) in solution: 1 oct2,snch oc\>- >b'p,r l,p ( to-to),) 5ncl,- :l'P' t I'P( 2 NF3,NC1. F is norc dic{onqia{.,"e. .'.NFE hos smollar hd lNi(H,o)61'?.(aq) + 6NH3(aq) + INi(NH3)61'?t(aq) + 6Hro(4 3 I3-, N3- 4. {.tErp bu}\) The equilibrium constant, K"r.b, of the above reaction, taking the concentration of water fer as being constant ls Given only the standard enthalpy changes of combustion of carbon, hydrogen and I N.(NH3)G'- ] b" methane, which of the following can be calculated? lttilttro;u'- I INH: ]u 1 Theenthalpychangeforthehypothetical reaction: A*r= AHc.(rx+)-aftctpl) - 2CO,(s) + 4H,OO :) 2CHa(s) + 4O,(s) =f }alA.,a, *r+a$c (HJl- >al\c(cHa ) The following table lists some iron complexes together with their colours and the values 2 The enthalpy change of formation of water. =6$.4611 of their stability constants larger (c,uu.e 3 The enthalpy change of formatron of liquid methane. oriltlJll( '- (.'i I tr \ is g) sld LodNors/ comolex colour K.uu '.(L\ lFe(SCN)(HrO)sl'-(aq) oeep reo 1x10' 3 ^+3X. 3 3 A 20 cm3 solution contains 1 x 10 mol dm and '1 x 10 mol dm Y2* metal ions. IFeFJ' (aq) cotoufless 2 x 1o'" b" 7 x 10* mol of sofid sodium sulfate is added to the solution. The numerical values of the tFe(CN)J"-(ao) oranqe-vellow 1x10" productof g.'1 sofubility X and Y sulfates arc7.4x 10-7 and x 10+ respectively. What can Fe(edta)l'-(ao cotouness 2x1O be deduced from this information? 1xl ( 1 The metal Y sulfate will precipitate out selectively. ledta = OTCCHT)TNCHTCHTN(CHrCO, )rl 2 There are more X* ions than Y2* ions remaining in the solution. 3 The solubility products of metal X and Y sulfates will change when 2 g of solid Which of the following statements are incorrect? sodium sutfate is added to the sorution f60 o.r\g oCf ec*ea bg +ernp. produces 1 Addition of KSCN(aq) to a solution of Fe3-(aq)'o a deep red solution which remarns red wnen KF(aq) is added. F; Slnn-ryf \gOd {rtUn 3N- +H}O . 2 Addition of edta to a solution containing (aq) does i'ot prodlce any colour A sample of copper which contains silver and zinc impurities can be purified by IFeF6l3,Nnqn Dto electrolysis. Which of the following statements are true? cnange ed\o. rc cs-\rrrrqr f\gind F- 3 Addition of KCN(aq) toliotutldn coniSining produces an 'r,s tre$bN)iHrd).1'.(aq) fu$ +)e oranse-yeltowsotution . 1 The impure copper is made the anode. Oo thAt fu -r . I *ott f' C1\- A Sihnsgr [3qftI +\n SCS[-+ HrtJ 2 Both zinc and silver are preferentiatty oxidised to n" ,"."Znir+.rtntOtq tUl- -c- 3 The concentration of the coppe(ll) ions in the electrolyte remains constant. - rq.c+l .1, '13 The responses A to D should be selected on the basis of The resoonses A to D should be selected on the basis of A B c D A B c D 1,2and3 1 and2 2and3 1 only 1, 2 and 3 1 and2 2and3 1 only onry are onry are only are only are correct correct cofrect correct correct correct correcl No other mmbination of statements is used as a correct response. No other combination of statements is used as a correct response. Ka The pK" vatues of the fottowing compounds are given o",o* I'u'icr at Which products are formed when phenyl propanoate undgrgoes acidic hydrolysis in the Ct ff^: !p9 D 18o a slorgcr a.H. presence of warer rabered with the ,"o*oo"t ' _o +H _tb _ u (bn\uqdl( Compound pK. at\roA^il t O l\(6 r- H,CO" 6.4 1 cH3 cHrcotuoH CF3COOH 0.2 2 cuHrtuoH \--s a Cj\rC\A'O CH3CH'OH 16.0 r cuHuco,uos cvfrn,L_b*H + Ho 10.0 S So- (o>"" R SS The structures and pK, values of fumaric acid and maleic acid are given below: 3.4 o,s{Sco- o,ru{Q!cooH pl(", pK., HOOC H 3.0 4.5 \-//\ 3A!o-Srl H COOH fumaric acid 1.9 7 In which of the following acid-base reactions will the equilibriuF favour the products over HOOC COOH thereactants? $O(sC' OddS dis?htr Ne.at€r odds. ,/\\=-/ HH 1 /F\, /t----\ (( + o . H2co3 maleic acid ))-ou Hco3------: Q)) 5|t\rgat odA Which of the following statements are correct? 1 Maleic acrd has a lower boiling point than fuma(ic acid as it can form intra- ( cooH NHr coo morecurar hydrogen bonding el\efi o{ rf*q969\0qr5r H -!r\ \t ) _jl' 2 pK", of maleic acid is larger than that of fumaric acid because the acidic A hydrogen atom in maleic acid can be stabilised by intra-molecular hydfogen l( )l + A rA tall bonding, hence making it more difficult to remove. (\_/, 3 For each acid, pKu2 is larger than pK,i because it is easier to remove a second Y Y Y proton from the conjugate base formed in the first ionisation.\ q1)U 1 d${ar"X$ tO Y ocH3 NOr ocH3 Noz Curuvt )rd Hr -&\.o +^gc ocrt ncg"h'U dmqed ll base ' + -C. + CH.CH"OH trruqgaFe- cF{-C- 'oH cH3cH2o CFz' O - SNgrddd The responses A to D should be selected on the basis of A B c D .lanaz t and 2 ano 1 only are only afe only are ts correct correct co rrect correcl No other combination of statements is used as a correct response. 40 Consider the following reaction scheme. C I CH3CH2SH+ CH3O + CH3CH2S + CH3OH CH3CH2S + C,H2 ,CH2 4 CH3CH2SCH2CH2O o .+III CH3CH2SCH2CH2O * *r9. CH3CH2SCH2CH2OH + oH' Bo:a Aod 'JJ\\\tr/r* e &,rd tflse Which of the following types of reactions are shown m reections L II and ,,,yj\sf( 1 oxidation 2 nucteophilic substituiion ( Re6diqn 1) 3 neutralisatrn t'RUCiiU^ frf 1' END OF PAPER 17