1. C[1] 2. B[1] 3. C[1] 4. C[1] 5. (a) k increases with increase in T / k decreases with decrease in T; 1Do not allow answers giving just the Arrhenius equation or involvingln k relationships. (b) gradient = Ea/R;30000 (K) = Ea/R;Allow value in range 2880031300 (K).Ea =(30000 8.31=) 2.49 105 J mol1 /249 kJ mol1; 3Allow value in range 240260 kJ mol1.Allow [3] for correct final answer. (c) 0.9 0.200 = 0.180 (mol dm3);rate = (0.244 (0.180)2 =) 7.91 103 mol dm3 s1; 2Award [2] for correct final answer.Award [1 max] for either 9.76 103 mol dm3 s1 or9.76 105 mol dm3 s1.[6] 6. C[1] 7. A[1] IB Questionbank Chemistry 18. (i) the concentration (of nitrogen(II) oxide); 1Award [0] if reference made to equilibrium. (ii) mol2 dm6 s1 / dm6 mol2 s1; 1Accept (mol1 dm3)2 s1.[2] 9. C[1] 10. B[1] 11. (a) to maintain a constant volume / OWTTE; 1 (b) (i) [H+] order 1, [CH3COCH3] order 1, [I2] order 0;(rate =) k[H+] [CH3COCH3];Award [2] for correct rate expression.Allow expressions including [I2]0. 2 (ii) neither were correct / Alex was right about propanone and wrongabout iodine / Hannah was right about propanone and hydrogen ionsbut wrong about iodine / OWTTE; 1 (c) [CH3COCH3] = 0.100 mol dm3 and [H+] = 0.100 mol dm3;k = ) 100 . 0 100 . 0 (10 96 . 46 = 4.96 104;mol1 dm3 s1;Ignore calculation of [I2].No ECF here for incorrect units. 3IB Questionbank Chemistry 2(d) (i)axes correctly labelled x = energy/velocity/speed, y = number/% ofmolecules/particles/probability;graph showing correct curve for Maxwell-Boltzmann distribution;If two curves are drawn, first and second marks can still be scored,but not third.Curve(s) must begin at origin and not go up at high energy.two activation energies shown with Ecat shown lower;Award the mark for the final point if shown on an enthalpylevel diagram. 3 (ii) catalyst provides an alternative pathway of lower energy / OWTTE;Accept catalyst lowers activation energy (of reaction). 1[11] 12. D[1] 13. D[1] 14. C[1] 15. B[1]IB Questionbank Chemistry 316. (a)First and second structures should be mirror images.Tetrahedral arrangement around carbon must be shown. 2 (b) (i) order with respect to OH = 0;order with respect to X = 1;rate = k[X];Award [3] for final correct answer. 3 (ii) 0.2(0);min1; 2 (iii) 2-bromo-2-methyl-propane;Do not penalize missing hyphens or added spaces.Accept 2-bromomethylpropane.tertiary (structure); 2 (iv) C4H9Br C4H9+ + Br / in equation with curly arrows and slow;C4H9+ + OH C4H9OH / in equation with curly arrows and fast;No penalty if primary structure is shown.No credit for SN2 mechanism, except by ECF. 2[11] 17. C[1] 18. C[1]IB Questionbank Chemistry 419. B[1] 20. C[1] 21. B[1] 22. (i) (from experiments 1 and 2 at constant [H2]), [NO] doubles, rate quadruples;hence, second order with respect to NO;(from experiments 2 and 3 at constant [NO]), [H2] doubles, rate doubles;first order with respect to H2;Allow alternative mathematical deductions also. 4 (ii) rate = k[NO]2 [H2]; 1 (iii) k (= (10.00 105)/(10.00 103)2 (4.00 103)) = 2.50 102;Do not penalize if Experiments 1 or 2 are used to determine k.mol2 dm6 s1; 2[7] 23. (i) step 1 / equation showing step 1; 1(ii) O (atom) / oxygen atom;Do not allow oxygen or O2. 1[2] 24. (i) (minimum) energy needed for a reaction to occur / difference inenergy between the reactants and transition state; 1IB Questionbank Chemistry 5(ii)correct position of activation energy;correct position of H and H(CH3NC)/reactant line above H(CH3CN)/product line;Accept E instead of H on diagram if y-axis is labelled as energy.Do not penalize if CH3NC and CH3CN are not labelled on diagram.correct position of transition state;Allow [2 max] if axes are not labelled on diagram. 3 (iii) as temperature/T increases rate constant/k increases (exponentially); 1 (iv) from graph gradient m = REa;measurement of gradient from chosen points on graph;Units of m are K. Do not penalize if not given, but do not award mark forincorrect units.Value of m is based on any two suitable points well separated on the plot.correct answer for Ea;correct units corresponding to answer;Note: A typical answer for Ea = 1.6 102 kJ / kJ mol1. 4[9] 25. C[1]IB Questionbank Chemistry 626. D[1] 27. (i) rate = k[NO]2 [Cl2]; 1 (ii) rate of reaction will decrease by a factor of 4;no effect on the rate constant; 2 (iii)y axis labelled concentration/mol dm3 and x axis is labelled time/s;gradient for [NO];gradient for [NOCl] will be equal and opposite;equilibrium point identified / two curves level off at same time; 4[7] 28. Above 775 K: rate = k[NO2][CO];Below 775 K: rate = k[NO2]2; 2[2] 29. zero order reaction;all concentrations are 1.0 mol dm3; 2[2]IB Questionbank Chemistry 730. slope = 310 ) 65 . 3 53 . 3 (4 . 8 2 . 9 = 6.67 103;(Ea = 6.67 103 8.31)55.4 (kJ mol1);Accept in range 55.0 56.0Award [1] if 55454 (J) statedAward [2] for the correct final answer 2[2] 31. C[1] 32. (a) (order with respect to) H2 = 1;(order with respect to) NO = 2; 2 (b) rate = k[H2][NO]2; 1ECF from (a). (c) (2.53106 mol dm3 s1 = k(0.100 mol dm3)(0.100 mol dm3)2)k = 2.53103;mol2 dm6 s1; 2ECF from (b). (d) agrees/yes;slow step depends on X and NO;(so) NO is involved twice and H2 once;overall equation matches the stoichiometric equation / OWTTE;ECF for no, depending on answer for (b).ORagrees/yes;and NO] ][ [HX] [2 = constant;rate of slow step = k[X][NO];but X depends on H2 and NO;rate of slow step = k[H2][NO]2; 4 maxAward [1] each for any three of the four above.ECF for no, depending on answer for (b).IB Questionbank Chemistry 8(e) reaction involves four molecules;statistically/geometrically unlikely; 2 (f) the rate of formation of H2O = 2rate for N2;because 2 moles H2O formed with 1 mole N2 / OWTTE; 2[13] 33. C[1] 34. B[1] 35. A[1] 36. B[1] 37. D[1] 38. (i) increase in concentration of product per unit time / decreasein concentration of reactant per unit time; 1Accept change instead of increase/decrease and mass/amount/volume instead of concentration. (ii) frequency of collisions;kinetic energy/speed of reactant particles;collision geometry/orientation; 3[4]IB Questionbank Chemistry 939.correctly labelled axes showing number of particles/frequency against(kinetic) energy;correctly shaped graph for T (curve must not touch or cross x axes);T curve to the right of T and with a peak lower than T;increasing the temperature increases the (kinetic) energy of theparticles / more particles will possess the necessary activation energy;there will be more collisions per unit time / the frequency of collisionsincreases / there are more successful collisions; 5[5] 40. D[1] 41. C[1] 42. C[1] 43. (a) [I2] does not affect rate / OWTTE;neither correct/both partially correct with explanation as to how; 2 (b) more particles/molecules have sufficient energy to overcomeactivation energy / OWTTE;more frequent collisions; 2 IB Questionbank Chemistry 10(c) (i)axes correctly labelled x = energy/velocity/speed, y = number/% ofmolecules/particles/probability;graph showing correct curve for Maxwell-Boltzmann distribution;If two curves are drawn, first and second mark can still be scored, but notthird.Curve(s) must begin at origin and not go up at high energy.two activation energies shown with Ecat shown lower;Award the mark for the final point if shown on an enthalpylevel diagram. 3 (ii) catalyst provides an alternative pathway of lower energy / OWTTE;Accept catalyst lowers activation energy (of reaction). 1[8] 44. C[1] 45. D[1] 46. (i) rate = increase in timevolume = slope of graph;initially/to begin with steeper slope / fastest rate / volume of gas/CO2produced faster/quickly as concentration of HCl highest / OWTTE;as reaction progresses/with time, less steep slope / volume of gasproduction slows / rate decreases due to less frequent collisionsas concentration (of HCl) decreases / OWTTE;curve flattens/becomes horizontal when HCl used up/consumed(as there are no more H+ ions to collide with the CaCO3 particles);Each mark requires explanation. 3 maxIB Questionbank Chemistry 11(ii)less steep curve;same maximum volume at later time;half/lower H+ /acid concentration less frequent collisions/slower rate;same amount of HCl, same volume CO2 produced; 4 (iii) mass loss/of CO2 / mass of flask + content;ORORDo not penalize for missing x-axis label or for missing units on y-axis.Accept if line meets time axis. 2 (iv) minimum energy (of colliding particles) for a reaction to occur / OWTTE;lower Ea / greater surface area/contact between CaCO3 and HCl / higher HClconcentration / (sufficient) particles/molecules have activation energy; 2[11]IB Questionbank Chemistry 1247. A[1] 48. A[1] 49. (i) exothermic;Accept either of the following for the second mark.increasing temperature favours endothermic/reverse reaction;as yield decreases with increasing temperature; 2 max (ii) yield increases / equilibrium moves to the right / more ammonia;increase in pressure favours the reaction which has fewermoles of gaseous products; 2 (iii) (rate increases because) increase in frequency (of collisions);increase in energy (of collisions);more colliding molecules with E Ea; 2 max[6] 50. D[1] 51. D[1] 52. C[1] 53. C[1] 54. (a) (minimum) energy needed for a reaction to occur / (minimum) energydifference between reactants and transition state; 1 IB Questionbank Chemistry 13(b) particles must collide;appropriate collision geometry/orientation;E Ea; 2 max (c) Diagram showing:correct labelling of axes (enthalpy/H/(potential) energy for y-axis andtime/progress/course of reaction/reaction coordinate for x-axis) andH (products) line shown below H (reactants) line;correct labelling of the two curves, catalysed and uncatalysed;correct position of Ea shown with lines for a catalysed and uncatalysedreaction;the correct label H /change in enthalpy;Do not penalize if reactants and products are not labelled.If an endothermic reaction is shown, award [2 max] if all other parts areshown correctly. 3 max[6] 55. (i) decrease in concentration/mass/amount/volume of reactant with time /increase in concentration/mass/amount/volume of product with time /change in concentration/mass/amount/volume of reactant/product with time; 1 (ii) MgCO3(s) + 2HCl(aq) MgCl2(aq) + CO2(g) + H2O(l);Ignore state symbols. 1IB Questionbank Chemistry 14(iii)Plot starts at the origin and levels off.No mark awarded if axes are not labelled. 1 (iv) new curve reaches same height as original curve;new curve less steep than original curve;volume of gas produced is the same because the same amount ofacid is used;reaction is slower because concentration is decreased; 4[7] 56. B[1] 57. A[1]IB Questionbank Chemistry 1558.labelled axes (including appropriate units);correctly drawn curve;correctly drawn tangent;rate equal to slope/gradient of tangent (at given time) / rate = xy at time t;[3 max] for straight line graph or graph showing product formation. 4[4] 59. (a) (i) increases rate of reaction;molecules (of H2O2) collide more frequently / more collisionsper unit time;No ECF here. 2 (ii) no effect / (solution) remains unchanged;solid NaI is not reacting / aqueous solution of NaI is reacting / surfacearea of NaI is not relevant in preparing the solution / OWTTE; 2 (b) kinetic energy/speed of reacting molecules increases;frequency of collisions increases per unit time;greater proportion of molecules have energy greater thanactivation energy/Ea;Accept more energetic collisions. 3 max[7] 60. B[1] IB Questionbank Chemistry 1661. A[1] 62. D[1] 63. A[1] 64. D[1] 65. D[1] 66. the reaction gives out (Gibbs Free) energy that can do work;G for the reaction has a negative value;a reaction that occurs without adding energy (beyond that required toovercome energy barrier); 1 max[1] 67. (i) by definition HhO of elements (in their standard states) is zero / noreaction involved / OWTTE; 1 (ii) H = 104 (+20.4);= 124.4 (kJ mol1); 2Award [1 max] for 124.4 (kJ mol1).Award [2] for correct final answer. (iii) S = 270 (267 + 131);= 128 (J K mol1); 2Award [1 max] for +128 (J K1 mol1).Award [2] for correct final answer.IB Questionbank Chemistry 17(iv) G = H TS = 124.4 1000) 298 128 ( ;= 86.3 kJ mol1; 2Units needed for the mark.Award [2] for correct final answer.Allow ECF if only one error in first marking point. (v) G = H TS = 0 / H = TS;T = 1000 / 1284 . 124 = 972 K / 699 C; 2Only penalize incorrect units for T and inconsistent S valueonce in (iv) and (v).[9] 68. C[1] 69. A[1] 70. C[1] 71. (a) (i) correct substitution of values and numbers of bonds broken /(1 945) + (3 436)/2253;correct substitution of values and numbers of bonds made /(6391)/2346;H = (sum of energies of bonds broken) (sum of energiesof bonds formed) = (22532346) = 93 (kJ);Ignore units.Award [3] for correct final answer.Award [2 max] for +93 or 93. 3IB Questionbank Chemistry 18(ii) entropy of products = 2 192 = 384;entropy of reactants = 193 + (3 131) = 586;SO (= sum of entropies of products) (sum of entropies ofreactants) / (384 586) = 202 (J K1 mol1);Award [3] for correct final answer.Award [2 max] for +202 or 202.Ignore units.negative as more ordered/less disordered / four molesbecome two moles / fewer molecules of gas; 4 (iii) (GO = HO TSO = 93 298(0.202)) = 32.8 (kJ mol1); 1 (iv) reaction becomes less spontaneous;G becomes more positive/less negative /TS becomes larger; 2 (b) macroscopic properties remain constant / concentrations remain constant / nochange to copper solution seen;rate of reverse/backwards reaction = rate of forward reaction; 2 (c) (Kc =)32 23] H ][ N [] NH [Do not award mark if [ ] missing or round brackets used. 1 (d) (i) [H2] = 0.11 / 0.11 (mol dm3);[N2] = 0.17 / 0.17 (mol dm3);Kc = 16;Ignore units.Allow ECF from incorrect equilibrium expression and incorrectconcentrations for third mark. 3 (ii) decrease;heat is a product/reaction is exothermic so equilibriummoves to left / OWTTE; 2 (e) yield increases / equilibrium moves to the right / more ammonia;4 gas molecules 2 / decrease in volume / fewer gas moleculeson right hand side; 2IB Questionbank Chemistry 19(f) high pressure expensive / greater cost of operating at high pressure /reinforced pipes etc. needed;Do not accept high pressure is dangerous without further explanation.lower temperature greater yield, but lowers rate;Do not award a mark just for the word compromise. 2 (g) Kc unaffected;position of equilibrium unaffected;rate of forward and reverse reactions are increased (equally); 3[25] 72. A[1] 73. B[1] 74. A[1] 75. C[1] 76. A[1] 77. D[1] 78. C[1]IB Questionbank Chemistry 2079. (i) I:atomization/sublimation (of Mg) / HOatomization(Mg) / HOsublimation(Mg);V:enthalpy change of formation of (MgCl2) / HOformation(MgCl2); 2 (ii) Energy value for II:+243;Energy value for III:738 + 1451 = 2189;Energy value for IV:2(349);HOlat(MgCl2) = 642 + 148 + 243 + 2189 = (+)2252(KJ); 4 (iii) theoretical value assumes ionic model;experimental value greater due to (additional) covalent character; 2 (iv) oxide greater charge;oxide smaller radius;Accept opposite arguments. 2[10] 80. A[1] 81. A[1] 82. B[1] 83. (i) c: atomization (enthalpy);d: electron affinity; 2 (ii) d and e; 1IB Questionbank Chemistry 21(iii) Hf = 90.0 + 418 + 112 + (342) + (670); = 392 kJ mol1; 2 (iv) Ca2+ is smaller than K+ and Ca2+ has more charge than K+ / Ca2+ has agreater charge density;so the attractive forces between the ions are stronger;Do not accept stronger ionic bondsAward [1 max] if reference is made to atoms or molecules instead of ions. 2[7] 84. B[1] 85. A[1] 86. (a) HOreaction = HfO(products) HfO(reactants)= [(1)(85) + (2)(242)] [(2)(201)];= 167 (kJ/kJ mol1);Award [1] for (+) 167. 2 (b) SOreaction = SO(products) SO(reactants)= [(1)(230) + (2)(189)] [(2)(238) + (1)(131)];= 1 (J K1/J K1 mol1); 2 (c) GOreaction = (HO TSO) = (167) (298)(0.001);Award [1] for correct substitution of values.= 167 kJ/167000 J;Units needed for mark in (c) only.Accept 167 kJ mol1 or 167000 J mol1.spontaneous;Award marks for final correct answers throughout in each of (a), (b) and (c). 3[7]IB Questionbank Chemistry 2287. (i) energy required to break (1 mol of) a bond in a gaseous molecule/state;Accept energy released when (1 mol of) a bond is formed in a gaseousmolecule/state / enthalpy change when (1 mol of) bonds are made orbroken in the gaseous molecule/state.average values obtained from a number of similar bonds/compounds / OWTTE; 2 (ii) Bonds broken(1)(CC) + (1)(OH) + (5)(CH) + (1)(CO) + (3)(O=O)= (1)(347) + (1)(464) + (5)(413) + (1)(358) + (3)(498) = 4728 (kJ);Bonds formed(2 2)(C=O) + (3 2)(OH)= (4)(746) + (6)(464) = 5768(kJ);H = 4728 5768 = 1040 kJ mol1 / 1040 kJ;Units needed for last mark.Award [3] for final correct answer.Award [2] for +1040 kJ. 3 (iii) Mr(C2H5OH) = 46.08 / 46.1 and Mr(C8H18) = 114.26/114.3;1 g ethanol produces 22.57 kJ and 1 g octane produces 47.88 kJ;Accept values ranges of 22.523 and 47.848 kJ respectively.No penalty for use of Mr = 46 and Mr = 114. 2[7] 88. C[1] 89. D[1] 90. (i) A: sublimation/atomization;B: atomization/half dissociation enthalpy;D: (sum of 1st and 2nd) electron affinity;Do not accept vaporization for A and B.Accept HAT. or HEA. 3 (ii) enthalpy change when one mole of the compound is formedfrom its elements (in their standard states);under standard conditions / 25 C/298 K and 1 atm/101.3 kPa/1.01 105 Pa; 2IB Questionbank Chemistry 23(iii) 602 = 150 + 248 + 2186 + 702 + E;3888 (kJ mol1);Do not allow 3889 (given in data booklet).Allow 3888 (i.e no minus sign).Award [2] for the correct final answer. 2 (iv) energy required to remove one electron;from an atom in its gaseous state;electron removed from a positive ion;decrease in electron-electron repulsion / increase innucleus-electron attraction;4 (v) MgO;double ionic charge / both ions carry +2 and 2 charge/greater chargecompared to +1 and 1; 2[13] 91. (i) (C2H6(g) + 321O2(g) 2CO2(g) + 3H2O(l)) HO = 1560;(H2O(l) H2(g) + 21O2(g)) HO = +286;(2CO2(g) + 2H2O(l) C2H4(g) + 3O2(g)) HO = +1411;(C2H6(g) C2H4(g) + H2(g)) HO = +137 (kJ);Allow other correct methods.Award [2] for 137.Allow ECF for the final marking point. 4 (ii) positive;increase in number of moles of gas; 2 (iii) at low temperature, HO is positive and G is positive;at high temperature, factor TSO predominates and G is negative; 2 (iv) Bonds broken (1CC, 6CH, or 1CC, 2CH) = 2825/1173;Bonds made (1C=C, 1HH, 4CH) = 2700/1048;+125 (kJ);Allow 125 but not 125 (kJ ) for the final mark.Award [3] for the correct final answer. 3 (v) bond enthalpy values are average values; 1[8]IB Questionbank Chemistry 2492. B[1] 93. C[1] 94. B[1] 95. D[1] 96. (i) lattice enthalpy for a particular ionic compound is defined as H for theprocess, MX(s) M+(g) + X(g);Accept definition for exothermic processelectron affinity is the energy change that occurs when an electron is addedto a gaseous atom or ion; 2IB Questionbank Chemistry 25(ii)N a ( s )+ 1 0 8 k J m o l 1+N a ( g )N a ( g )++ H = 4 1 1 k J m o l 1+ 4 9 4 k J m o l 1C l ( g )12 N a C l ( s )+ 1 2 1 k J m o l 3 6 4 k J m o lC l ( g )C l ( g )f 1 12lattice enthalpy= [(411) (+108) (+494) (+121) (364)]= 770 (kJ mol1)Award [2] for all correct formulas in correct positions on cycle diagram.1 incorrect or missing label award [1].Award [1] for all correct values in correct positions on cycle diagram.calculation of lattice enthalpy of NaCl(s) = 770 (kJ mol1); 4Allow ECF.Accept alternative method e.g. energy level diagram. (iii) lattice/network/regular structure;each chloride ion is surrounded by six sodium ions and each sodium ion issurrounded by six chloride ions/6:6 coordination; 2[8] 97. B[1] 98. A[1] 99. C[1]IB Questionbank Chemistry 26100. (a) amount of energy required to break bonds of reactants3 413 + 358 + 464 + 1.5 498 (kJ mol1) / 2808 (kJ mol1);amount of energy released during bond formation of products4 464 + 2 746 (kJ mol1) / 3348 (kJ mol1);H = 540 (kJ mol1); 3Award [3] for correct final answer.Award [2] for (+)540.If old Data Booklet is used accept answer: 535 (kJ mol1) oraward [2] for (+)535. (b) (i) m(methanol) = (80.557 80.034) = 0.523 (g);n(methanol) =

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1mol g 32.05g 523 . 0 = 0.0163 (mol); 2Award [2] for correct final answer. (ii) T = (26.4 21.5) = 4.9 (K);q = (mcT =) 20.000 4.18 4.9 (J) / 20.000 4.18 4.9 103 (kJ);0.41 (kJ); 3Award [3] for correct final answer. (iii) HcO = (mol) 0.0163(kJ) 41 . 0 / 25153 (J mol1);= 25 (kJ mol1); 2Award [2] for correct final answer.Award [1] for (+)25 (kJ mol1). (c) (i) bond enthalpies are average values/differ (slightly) fromone compound to another (depending on the neighbouringatoms) / methanol is liquid not gas in the reaction; 1 (ii) not all heat produced transferred to water / heat lost tosurroundings/environment / OWTTE / incomplete combustion(of methanol) / water forms as H2O(l) instead of H2O(g) ; 1Do not allow just heat lost.[12] 101. A[1]IB Questionbank Chemistry 27102. D[1] 103. C[1] 104. (a) (i) amount = 61 . 15999 . 3 = 0.0250 (mol); 1 (ii) 26.1 (C);Accept answers between 26.0 and 26.2 (C).temperature rise = 26.1 19.1 = 7.0 (C); 2Accept answers between 6.9 C and (7.1 C).Award [2] for the correct final answer.No ECF if both initial and final temperatures incorrect.IB Questionbank Chemistry 28(iii) heat change = 10000 . 50 4.18 7.0 / 50.0 4.18 7.0;Accept 53.99 instead of 50.0 for mass.= 1.5 (kJ); 2Allow 1.6 (kJ) if mass of 53.99 is used.Ignore sign. (iv) H1 = 0250 . 05 . 1 = 60 (kJ mol1); 1Value must be negative to award mark.Accept answers in range 58.0 to 60.0.Allow 63 (kJ mol1) if 53.99 g is used in (iii). (b) (i) (amount of CuSO45H2O = 71 . 24924 . 6 =) 0.0250 (mol);(amount of H2O in 0.0250 mol of CuSO45H2O= 5 0.0250 =) 0.125 (mol). 2 (ii) (50.0 4.18 1.10 =) 230 (J);

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0250 . 0 1000 (9 . 229 + 9.20 (kJ); 2Accept mass of 47.75 or 53.99 instead of 50.00 giving answersof +8.78 or +9.9.Do not penalize missing + sign but penalize sign unless chargealready penalized in (a) (iv). (iii) (Hx = H1 H2 = 58.4 (+9.20) =) 67.6 (kJ mol1); 1 (c) (i)0 . 78)] 6 . 67 ( 0 . 78 [ 100 = 13.3 %; 1If 70.0 kJ mol1 is used accept 10.3 %. (ii) the anhydrous copper(II) sulfate had already absorbedsome water from the air / OWTTE;the value would be less exothermic/less negative thanexpected as the temperature increase would be lower /less heat will be evolved when the anhydrous salt isdissolved in water / OWTTE; 2Do not accept less without a reason.[14]IB Questionbank Chemistry 29105. (i) nickel / platinum / palladium;150200 C / heat; 2Accept temperatures in this range.Accept room temperature as an answer if platinum or palladium used. (ii) the enthalpy change when (one mole of) the gaseous bond isbroken (or formed) / XY(g) X(g) + Y(g) / X(g) + Y(g) XY(g);averaged for the same bond in a number of similar compounds / OWTTE; 2 (iii) energy in: C=C + HH and energy out: CC + 2CH;Accept energy in CC + 6CH + C=C + HH and energyout 2CC + 8CH.H = (612 + 436) (347 + 826) = 1048 1173 / 125 (kJ mol1); 2Award [2] for correct final answer.Award [1] for +125.If old Data Booklet values then allow: H = 1048 1172= 124 (kJ mol1) (iv) due to the relative strength of the CC and 2CH bondscompared to the C=C and HH bonds / bonds in productsstronger than bonds in reactants; 1[7] 106. A[1] 107. B[1] 108. D[1] 109. (i) 100 4.18 35.0;14630 J / 14600 J / 14.6 kJ;Award [2] for correct final answer.No ECF here if incorrect mass used. 2IB Questionbank Chemistry 30(ii)08 . 4678 . 1 =0.0386 mol;0386 . 06 . 14 = ()378 kJ mol1;Accept ()377 and ()379 kJ mol1.Award [2] for correct final answer. 2 (iii) heat loss;incomplete combustion;heat absorbed by calorimeter not included;Accept other sensible suggestions. 2 max[6] 110. B[1] 111. C[1] 112. C[1] 113. B[1] 114. A[1] 115. B[1]IB Questionbank Chemistry 31116. (a) all heat is transferred to water/copper sulfate solution / no heat loss;specific heat capacity of zinc is zero/negligible / no heat isabsorbed by the zinc;density of water/solution = 1.0 / density of solution = density of water;heat capacity of cup is zero / no heat is absorbed by the cup;specific heat capacity of solution = specific heat capacity of water;temperature uniform throughout solution;Award [1] each for any two.Accept energy instead of heat. 2 max (b) (i) Tfinal = 73.0 (C);Allow in the range 72 to 74 (C).T = 48.2 (C);Allow in the range 47 to 49 (C).Award [2] for correct final answerAllow ECF if Tfinal or Tinitial correct. 2 (ii) temperature decreases at uniform rate (when above roomtemperature) / OWTTE; 1 (iii) 10.1 (kJ);Allow in the range 9.9 to 10.2 (kJ). 1 (c)

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10000 . 50 00 . 14CuSO Znn n = 0.0500(mol); 1 (d) 201(kJ mol1);Allow in the range 197 to 206 (kJ mol1).Value must be negative to award mark. 1[8] 117. (i) the more reactive the metal the more negative the enthalpy change/the more exothermic the reaction / OWTTE;Do not accept greater enthalpy change. 1 (ii) any curve with positive gradient which passes through H = 0 at Cu;Allow point graph or histogram.Accept either positive or zero enthalpy change for Ag. 1[2]IB Questionbank Chemistry 32118. bonds broken: 4 NH, NN, O=O / +2220 (kJ mol1);bonds formed: 1 NN, 4OH / 2801(kJ mol1);581 (kJ mol1);Award [3] for correct final answer. 3[3] 119. D[1] 120. B[1] 121. D[1] 122. (a) energy required = C=C + HH/612 + 436 andenergy released = CC + 2(CH)/347 +2(413) /energy required = C=C + HH + 4(CH)/612 + 436 + 4(413) andenergy released = CC + 6(CH)/347 + 6(413);H = (1048 1173)/(2700 2825) = 125 kJ mol1; 2 (b) H = 1411 + (286) (1560) = 137 kJ mol1; 1 (c) the actual values for the specific bonds may be different to the averagevalues / the combustion values referred to the specific compounds / OWTTE; 1 (d) (i) 125 kJ mol1; 1 (ii) average bond enthalpies do not apply to the liquid state / OWTTE;the enthalpy of vaporization/condensation of cyclohexene andcyclohexane / OWTTE; 2[7] 123. C[1] IB Questionbank Chemistry 33124. (a) energy required = C=C + HH/612 + 436 andenergy released = CC + 2(CH)/347 + 2(413) /energy required = C=C + HH + 4(CH)/612 + 436 + 4(413) andenergy released = CC + 6(CH)/347 + 6(413);H = (1048 1173)/(2700 2825) = 125 kJ mol12 (b) H = 1411 + (286) (1560)/correct energy cycle drawn;= 137 kJ mol1;Award [1 max] for incorrect or missing sign. 2 (c) the actual values for the specific bonds may be different to the averagevalues / the combustion values referred to the specific compounds / OWTTE;(percentage difference) = 137) 125 137 ( 100 = 8.76 %;Accept 125125) (137 100 = 9.60 %. 2 (d) (i) 125 kJ mol1; 1 (ii) average bond enthalpies do not apply to the liquid state / OWTTE;the enthalpy of vaporization/condensation of cyclohexene andcyclohexane / OWTTE; 2[9] 125. B[1] 126. D[1] 127. A[1] 128. D[1]IB Questionbank Chemistry 34129. (i) energy required to break (1 mol of) a bond in a gaseous molecule/state;Accept energy released when (1 mol of) a bond is formed in a gaseousmolecule/state / enthalpy change when (1 mol of) bonds are made orbroken in the gaseous molecule/state.average values obtained from a number of similar bonds/compounds / OWTTE; 2 (ii) Bonds broken(1)(CC) + (1)(OH) + (5)(CH) + (1)(CO) + (3)(O=O)= (1)(347) + (1)(464) + (5)(413) + (1)(358) + (3)(498) = 4728(kJ);Bonds formed(2 2)(C=O) + (3 2)(OH)= (4)(746) + (6)(464) = 5768 (kJ);H = 4728 5768 = 1040 kJ mol1 / 1040 kJ;Units needed for last mark.Award [3] for final correct answer.Award [2] for +1040 kJ. 3 (iii) Mr(C2H5OH) = 46.08 / 46.1 and Mr(C8H18) = 114.26/114.3;1 g ethanol produces 22.57 kJ and 1 g octane produces 47.88 kJ;Accept values ranges of 22.523 and 47.848 kJ respectively.No penalty for use of Mr = 46 and Mr = 114. 2 (iv) A: CH3CHO;B: CH3COOH/CH3CO2H;Accept either full or condensed structural formulas but not thenames or molecular formulas.A: distillation;B: reflux; 4 (v) ethanol/CH3CH2OH;hydrogen bonding (in ethanol);Award second point only if the first is obtained. 2 (vi) (concentrated) H3PO4 /(concentrated) phosphoric acid / H2SO4/sulfuric acid;dyes / drugs / cosmetics / solvent / (used to make) esters / (used in) esterification/disinfectant; 2[16] 130. A[1]IB Questionbank Chemistry 35131. D[1] 132. C[1] 133. (C2H6(g) + 321O2(g) 2CO2(g) + 3H2O(l)) HO = 1560;(H2O(l) H2(g) + 21O2(g)) HO = +286;(2CO2(g) + 2H2O(l) C2H4(g) + 3O2(g)) HO = +1411;(C2H6(g) C2H4(g) + H2(g)) HO = +137(kJ);Allow other correct methods.Award [2] for 137.Allow ECF for the final marking point. 4[4] 134. C[1] 135. C[1] 136. B[1] 137. (a) T = 23.70 23.03 = 0.67 (C/K); 1 (b)

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1mol g 342.34g 4385 . 0n = 1.281103 mol; 1 (c) (i) Hc = (C T)/n = mol) 10 281 . 1 (K)] 67 . 0 )( K kJ 114 . 10 [(31 = 5.3103 kJ mol1; 1Use ECF for values of T and n. IB Questionbank Chemistry 36(ii) Percentage experimental error =100) 10 6 . 5 () 10 6 . 5 ( ) 10 3 . 5 (33 31]1

+ = 5.4%; 1Use ECF for values of Hc. (d) enthalpy change of combustion of sucrose > TNT, and thereforenot important;rate of reaction for TNT is greater than that of sucrose, so this is valid;amount of gas generated (in mol) for sucrose > than that of TNT(according to the given equation), so this is not important; 3[7] 138. (a) The amount of energy needed to break 1 mole of (covalent) bonds;in the gaseous state;average calculated from a range of compounds; 2 maxAward [1] each for any two points above. (b) Bonds broken(612) + (2348) + (8412) + (6496)/7580 (kJ mol1);Bonds made(8743) + (8463) / 9648 (kJ mol1);H = 2068 (kJ mol1); 3Award [3] for the correct answer.Allow full ECF.Allow kJ but no other incorrect units.Even if the first two marks are lost, the candidate can score [1] for a clear correct subtraction for H.[5] 139. (i) fertilizers / increasing crop yields;production of explosives for mining; 1 max (ii) H = (sum of energies of bonds broken) (sum of energies of bonds formed);Can be implied by working.correct substitution of values and numbers of bonds broken;correct substitution of values and numbers of bonds made;(H = (N N) + 3(HH) 6(NH) = 944 + 3(436) 6(388) =) 76.0 (kJ); 4Allow ECF.Do not penalize for sig. fig. or units.Award [4] for correct final answer.IB Questionbank Chemistry 37(iii) (S[2193] [192 + 3131]) = 199 (J K1 mol1); 2Allow ECF.four gaseous molecules generating two gaseous molecules /fewer molecules of gas; (iv) (G = H TS = 76.0 298(0.199)) = 16.7 (kJ);Spontaneous;G is negative; 3Do not penalize for SF. (v) heat released when gas liquid;H becomes more negative; 2[12] 140. A[1] 141. B[1] 142. A[1]IB Questionbank Chemistry 38143. delocalization/spread of pi/ electrons over more than two nuclei;equal bond order/strength/length / spreading charge (equally) over allthree oxygens;gives carbonate ion a greater stability/lower potential energy; 3M3 can be scored independently.Accept suitable labelled diagrams for M1 and M2 e.g.ORDo not penalize missing brackets on resonance structure but 2 charge mustbe shown.Allow 2 for charge on resonance structure.[3]IB Questionbank Chemistry 39144. mixing/combining/merging of (atomic) orbitals to form new orbitals (for bonding);Allow molecular or hybrid instead of new.Do not allow answers such as changing shape/symmetries of atomic orbitals.Carbon dioxide: sp;Diamond: sp3;Graphite: sp2;Carbonate ion: sp2; 5[5] 145. C[1] 146. D[1] 147. A[1] 148. B[1] 149. C[1] 150. D[1] 151. D[1] 152. A[1] IB Questionbank Chemistry 40153. A[1] 154. (a) (i) (bond formed by) sideways overlap;(of) p orbitals;Marks awarded either from sketch or from explanation. 2 (ii) C(l) is sp3 and C(2) is sp2; 1 (b)cis but-2-ene/Z-but-2-ene; 2 (c)1[6] 155. (i) acid-base/neutralization; 1 (ii) 109 /109.5; 1 (iii) sp3;No ECF if bond angle incorrect in (ii). 1[3] 156. A[1]IB Questionbank Chemistry 41157. A[1] 158. A[1] 159. A[1] 160. A[1] 161. (i)octahedral/octahedron/square bipyramidal;90 / 90 and 180; 3 (ii)linear;180;Allow dots, crosses or lines in Lewis structures.Penalize missing charge, missing bracket once only in (i) and (ii).Lone pairs required for BOTH (i) and (ii). 3[6] 162. A[1]IB Questionbank Chemistry 42163.SF2SF4SF6Lewisstructure2 lone pairs on S required for the mark1 lone pair on S required for the markName ofshapebent/angular/V shaped; Seesaw/distorted tetrahedral;octahedral;Accept square bipyrimidalPenalize missing lone pairs on fluorine atoms once in correct structures only.For Lewis structures candidates are not expected to draw exact shapes of molecules.Do not allow ECF for wrong Lewis structures.Accept dots or crosses instead of lines. 6[6] 164. C[1] 165. D[1]IB Questionbank Chemistry 43166. (i)SpeciesLewis (electron-dot)structureShape Bond angle(s)NO2Bent/V-shaped/angular;109.5 < < 120;ICl5Square pyramidal;|Inplane Cl-I-out-of-plane Cl| < 90;Allow corresponding correctstatement for other correctly identifiedbond angles.SF4See-saw;|Equatorial F-S-Equatorial F| < 120;Allow corresponding correctstatement for axial-equatorial andaxial-axial F-S-F angles.9Accept crosses and dots for electrons in the Lewis structures also.If all ideal bond angles are given, penalize once only.As the Lewis structures were asked for, and not 3D representations, do not penalize incorrectly drawn geometries. (ii) (equatorial F-S-equatorial F) less than 120 since non-bonding electron pairs(exert greater repulsive forces and thus) compress the bond angles / OWTTE; 1 (iii) orbital diagram representation of carbon ground-state going to carbonexcited-state electron configuration;mixing of orbitals to give three new entirely equivalent hybrid orbitals, sp 2,on each carbon;sp2 orbitals trigonal (triangular) planar in shape;unhybridized orbitals overlap to give -bond; 4 (iv) sp2;both N-O bond lengths equal, (intermediate between double and singlebonds) due to resonance/delocalization; 2 (v) O-H is most polar;O-H has greatest difference between electronegativities / calculationshowing values of 1.4, 0.5 and 0.9 respectively; 2[18]IB Questionbank Chemistry 44167. D[1] 168. A[1] 169. C[1] 170. (i) calcium ionic charge is twice/greater than the potassium ionic charge /calcium has more delocalized electrons than potassium;greater attraction of delocalized electrons and Ca2+ / less attractionbetween the delocalized electrons and K+; 2Do not accept calcium ion has a 2+ without comparison to K+. (ii) Na2O ionic/(stronger electrostatic) attractions between Na+ and O2;SO3 has (weak) intermolecular/van der Waals/London/dispersion/dipole-dipole attractions;intermolecular/van der Waals/London/dispersion/dipole-dipole forcesare weaker/more easily broken than (strong) ionic bonds / ionic bondsare stronger/harder to break than intermolecular bond/van derWaals/London/dispersion/dipole-dipole forces; 3[5]IB Questionbank Chemistry 45171. Award [2 max] for three of the following features:BondingGraphite and C60 fullerene: covalent bonds and van der Waals/London/dispersion forces;Diamond: covalent bonds (and van der Waals/London/dispersion forces);Delocalized electronsGraphite and C60 fullerene: delocalized electrons;Diamond: no delocalized electrons;StructureDiamond: network/giant structure / macromolecular / three-dimensionalstructure and Graphite: layered structure / two-dimensionalstructure / planar;C60 fullerene: consists of molecules / spheres made of atoms arranged inhexagons/pentagons;Bond anglesGraphite: 120 and Diamond: 109;C60 fullerene: bond angles between 109120;Allow Graphite: sp2 and Diamond: sp3.Allow C60 fullerene: sp2 and sp3.Number of atoms each carbon is bonded toGraphite and C60 fullerene: each C atom attached to 3 others;Diamond: each C atom attached to 4 atoms / tetrahedralarrangement of C (atoms); 6 max[6] 172. ;linear and 180; 2Accept crosses, lines or dots as electron pairs.[2] 173. network/giant structure / macromolecular;each Si atom bonded covalently to 4 oxygen atoms and each Oatom bonded covalently to 2 Si atoms / single covalent bonds; 2Award [1 max] for answers such as network-covalent, giant-covalent ormacromolecular-covalent.Both M1 and M2 can be scored by a suitable diagram.[2]IB Questionbank Chemistry 46174. Silicon dioxide: strong/covalent bonds in network/giant structure/macromolecule;Carbon dioxide: weak/van der Waals/dispersion/London forces between molecules; 2[2] 175. triple (covalent) bond;one electron pair donated by oxygen to carbon atom / dative (covalent)/coordinate (covalent) bond; 2Award [1 max] for representation of CO.Award [2] if CO shown with dative covalent bond.[2] 176. A[1] 177. (a) vapour pressure ethoxyethane (81 103 Pa) > vapour pressurebenzene (16 103 Pa) > vapour pressure water (4 103 Pa);If three correct vapour pressure values related to each substanceare stated alone award M1.Allow range of 8085 103 Pa, 1418 103 Pa and 37 103 Pa.Do not award mark for comparisons of just two substances.water has hydrogen bonding;benzene has van der Waals/London/dispersion forces;ethoxyethane has dipoledipole forces (and van der Waals/London/dispersion) but they are weaker than benzene; 4 (b) 81 C; 1Allow 8082 C.[5] 178. Molten sodium oxide: conducts because of free moving/mobile ions inmolten state;Sulfur trioxide: doesnt conduct because no free moving/mobile chargedparticles/it has neutral molecules; 2Award [1 max] for stating molten sodium oxide conducts but sulfurtrioxide doesnt.Do not award M2 for just sulfur trioxide does not conduct becauseit is molecular.[2]IB Questionbank Chemistry 47179. B[1] 180. C[1] 181. B[1] 182. D[1] 183. C[1] 184. (a) (i) +3; 1Do not accept 3, 3+ or the use of Roman numerals. (ii) +5 / 3; 1Penalize incorrect format only if not penalized in (a)(i). (b) (i) Sb2S3 + 421O2 Sb2SO3 + 2SO2 / 2Sb2S3 + 9O2 2Sb2O3 + 6SO2;2Sb2O3 + 3C 4Sb + 3CO2 / Sb2O3 + 3C 2Sb + 3CO; 2Ignore state symbols. (ii) the SO2 causes acid rain / OWTTE;the CO2 is a greenhouse gas/causes global warming / OWTTE;CO is a poisonous gas / OWTTE; 2 max[6]IB Questionbank Chemistry 48185. methoxymethane is very weakly polarweak van der Waals/dipole-dipole forces exist between methoxymethanemolecules;Accept alternatives to van der Waals such as London and dispersion forces.ethanol contains a hydrogen atom bonded directly to an electronegativeoxygen atom / hydrogen bonding can occur between two ethanolmolecules / intermolecular hydrogen bonding in ethanol;the forces of attraction between molecules are stronger in ethanol thanin methoxymethane / hydrogen bonding stronger than van der Waals/dipole-dipole attractions; 3 maxAward [2 max] if covalent bonds breaking during boiling ismentioned in the answer.Penalize only once if no reference given to intermolecular natureof hydrogen bonding or van der Waal is missing.[3] 186. (i)Accept any combination of dots/crosses and lines to representelectron pairs.(trigonal/triangular) pyramid;Allow 3D representation using wedges and dotted bonds oftrigonal pyramidal molecule.107; 3Accept any angle between 105 and 108.5.No ECF for shape based on incorrect Lewis structure. (ii)Charge needed for mark.tetrahedral;Allow a 3D representation using wedges and dotted bondsof tetrahedral molecule.109.5/109/109 28'; 3No ECF for shape based on incorrect Lewis structure.[5]IB Questionbank Chemistry 49187. D[1] 188. A[1] 189. D[1] 190. D[1] 191. A[1] 192. A[1] 193. B[1] 194. (i)Accept lines, dots or crosses for electron pairs.Lone pairs required on chlorine.(approximately)120;Accept any bond angle in the range 113120. 2IB Questionbank Chemistry 50(ii)Brackets not required for mark.Allow correct condensed structural formula.Continuation bonds from each carbon are required.Cl atoms can be above or below carbon spine or alternatingabove and below. 1 (iii) plastics are cheap/versatile/a large industry / plastics havemany uses / OWTTE;plastics are not biodegradeable / plastics take up large amounts of space inlandfill / pollution caused by burning of plastics / OWTTE;Do not accept plastics cause litter.Allow plastics dont decompose quickly / OWTTE. 2[5] 195. A[1] 196. D[1] 197. B[1] 198. A[1] 199. B[1]IB Questionbank Chemistry 51200. D[1] 201. (a) N2H4(g) + 2F2(g) N2(g) + 4HF(g)Award [1] for reactants and products.Award [1] if this equation is correctly balanced.Ignore state symbols. 2 (b) Hydrazine:Nitrogen:N N ;Accept lines, dots and crosses to show electron pairs.Penalize missing lone pairs once only. 2 (c) BE (bonds broken) = (4 391) + 158 + 2(158) / 2038(kJ);BE (bonds formed) = (945) + 4(568) / 3217 (kJ);HO = 2038 3217 = 1179 (kJ);Award [3] for correct final answer.Award [2] for (+)1179 (kJ). 3 (d) (N2H4 / F2) better rocket fuel;ECF: answer must be consistent with equation in (a) and H in (c).5 vol/mol (g) > 3 vol/mol (g) / more moles/greater amount of gas produced;HO (N2H4 / F2) > HO (N2H4 / O2) (per mole) / (N2H4 / F2) reaction moreexothermic; 2 max[9] 202. B[1] 203. D[1]IB Questionbank Chemistry 52204. C[1] 205. D[1] 206. A[1] 207. metallic (bonding);positive ions/cations and delocalized/sea of electrons;electrostatic attraction between the two;Award [2 max] for description of bondingConductivity:electrons delocalized/free to move;Malleability:atoms/ions/cations can move without breaking bonds / atoms/ions/cations can slide past each other; 4[4] 208. (a) (i)Accept s, dots or lines for electron pairs. 2 (ii) HCH:any angle between 118 and 122;due to three negative charge centres/electron domains/electron pairs;HNH:any angle between 104 and 108;due to four negative charge centres/electron domains/electron pairs;extra repulsion due to lone electron pairs;Do not allow ECF for wrong Lewis structures. 5IB Questionbank Chemistry 53(b) (i) (relative) measure of an atoms attraction for electrons;in a covalent bond / shared pair; 2 (ii) CH is less polar as C is less electronegative / NH bond is more polaras N is more electronegative / difference in electronegativity is greaterfor N-H than C-H; 1 (iii) bond polarities cancel in C2H4 / OWTTE; 1 (c) weaker van der Waals/London/dispersion/intermolecular forces in ethene;stronger (intermolecular) hydrogen bonding in hydrazine;If no comparison between strengths then [1 max]. 2[13] 209. (i) acid-base/neutralization; 1 (ii) 109 /109.5; 1[2] 210. D[1] 211. C[1] 212. D[1] 213. A[1]IB Questionbank Chemistry 54214. (i)All outer electron pairs must be shown for mark in each case.Accept electrons shown as all x rather than and x. 3 (ii) CO < CO2 < CH3OH;triple bonds are shorter than double bonds which are shorter than singlebonds / the more pairs of electrons that are shared the stronger theattracting so the shorter the bond / OWTTE;The order must be correct to gain the second marking pointunless ECF from (a). 2[5] 215. (i) (CO2) linear;180; 2 (ii) (CO32) trigonal planar/triangular planar;120; 2 (iii) (BF4) tetrahedral;109.5 / 109 / 109 28; 2[6] 216. D[1]IB Questionbank Chemistry 55217. D[1] 218. D[1] 219. B[1] 220. C[1] 221. C[1] 222.Allow crosses or dots for lone-pair.trigonal/triangular pyramidal;(~)107 / less than 109.5;Do not allow ECF.LP-BP repulsion > BP-BP repulsion / one lone pair and three bond pairs /lone pairs/non-bonding pairs repel more than bonding-pairs;Do not accept repulsion between atoms. 4[4]IB Questionbank Chemistry 56223. boiling points increase going down the group (from PH3 to AsH3 to SbH3);Mr/number of electrons/molecular size increases down the group;Accept electron cloud increases down the group for the second marking point.greater dispersion/London/van der Waals forces;NH3/ammonia has a higher boiling point than expected due to the hydrogenbonding between the molecules;Do not accept hydrogen bonding alone. 4[4] 224. CO:Award [1] for showing the net dipole moment, or explaining it in words(unsymmetrical distribution of charge).NO2:Award [1] for correct representation of the bent shape and [1] for showing thenet dipole moment, or explaining it in words (unsymmetrical distribution of charge).CO2:Award [1] for correct representation of the linear shape and [1] for showing thetwo equal but opposite dipoles or explaining it in words (symmetricaldistribution of charge).For all three molecules, allow either arrow or arrow with bar forrepresentation of dipole moment.Allow correct partial charges instead of the representation of thevector dipole moment.Ignore incorrect bonds.Lone pairs not needed. 5[5] 225. Structure:network/giant lattice / macromolecular / repeating tetrahedral units;Bonding:(single) covalent (bonds);It is not necessary to identify which part refers to structure and bonding specifically. 2[2]IB Questionbank Chemistry 57226. B[1] 227. C[1] 228. C[1] 229. B[1] 230. C[1] 231.PF3SF2SiF4Lewisstructure1 lone pair on P required for the mark2 lone pairs on S required for the markName ofshapetrigonal/triangular pyramidal;bent/angular/V shaped; tetrahedral/tetrahedron;Penalize missing lone pairs on fluorine atoms once in correct structures only.For Lewis structures candidates are not expected to draw exact shapes of molecules.Do not allow ECF for wrong Lewis structures.Accept dots or crosses instead of lines. 6[6] 232. D[1]IB Questionbank Chemistry 58233. B[1] 234. B[1] 235. B[1] 236. D[1] 237. A[1] 238. B[1] 239. B[1] 240. (i) Find number of electron pairs/charge centres in (valence shell of)central atom;electron pairs/charge centres (in valence shell) of central atom repeleach other;Any one of the following:to positions of minimum energy/repulsion / maximum stability;pairs forming a double or triple bond act as a single bond;non-bonding pairs repel more than bonding pairs / OWTTE; 3 maxDo not accept repulsion between bonds or atoms.IB Questionbank Chemistry 59(ii) 6SpeciesLewis (electron-dot)structureShape Bond angle(s)H3O+OH HH+;Trigonal/triangularpyramidal;Allow values in therange 106 to 109.5;C2H4H;HH HTrigonal/triangularplanar;Allow values ofapproximately 120;Accept crosses and dots for electrons in Lewis structures also.As the Lewis structures were asked for, and not 3D representations, do not penalize incorrectly drawn geometries.Do not accept structure of hydronium cation without lone pair on oxygen.No penalty for missing charge. (iii) H3O+: is polar and explanation either using a diagram or in words,involving the net dipole moment;e.g. the three individual O-H bond dipole moments add as vectors to give a net dipole moment.C2H4: is non-polar and explanation either using a diagram or in words,involving no net dipole moment; 2e.g. the vector sum of the individual bond dipole moments is zero.For simple answers such as bond polarities do not cancel for H3O+ and do cancel for C2H4, Award [1], only for the last two marking points. (iv) O-H is most polar;O-H has greatest difference between electronegativities / calculationshowing values of 1.4, 0.5 and 0.9 respectively; 2[13] 241. BF3, N2O, P4O6 and CBr4;Non-metals only / small difference in electronegativity values of the elements; 2[2]IB Questionbank Chemistry 60242. (i) 3Allotrope StructureDiamond 3D array/network involving tetrahedral carbons / each carbon atom joined to four others;Graphite layer structure involving trigonal (triangular) planar carbons / with each carbon atom joined to three others / with hexagonal (six-membered) rings of carbon atoms;C60 fullerene truncated icosahedrons;Accept carbon atoms form a ball with 32 faces, ofwhich 12 are pentagons and 20 are hexagons,exactly like a soccer ball. Do not accept soccer ballalone. (ii) Diamond: covalent bonds (only);Graphite: covalent bonds and the separated layers held together by(weak) London/van der Waals/dispersion forces; 2[5] 243. Electrical conductivity:Bonding electrons are delocalized;Current flow occurs without displacement of atoms within the metal /able to flow within the metal;Malleability:Can be hammered into thin sheets;atoms capable of slipping with respect to one another; 4[4] 244. D[1] 245. C[1] 246. C[1]IB Questionbank Chemistry 61247. (i) the amount of energy required to remove one (mole of) electron(s);from (one mole of) an atom(s) in the gaseous state; 2 (ii) greater positive charge on nucleus / greater number of protons /greater core charge;greater attraction by Mg nucleus for electrons (in the same shell) /smaller atomic radius; 2[4] 248. A[1] 249. A[1] 250. A[1] 251. Down group 1:metallic bonding gets weaker;radii/atoms get bigger / delocalized electrons shielded/screened fromnucleus by filled shells;Down group 7:increased Mr of halogen molecules / OWTTE;intermolecular/van der Waals/London/dispersion forces increase; 4[4] 252. B[1] 253. (a) as (cat)ion becomes more positive / Na+, Mg2+, Al3+ / size/radius decreases /charge density increases;Do not allow increasing number of protons or increasing nuclear charge.attraction for mobile/valence/delocalized/sea of electrons increases;Do not accept cloud of electrons. 2IB Questionbank Chemistry 62(b) larger molecule / higher Mr/ M / greater number of electrons;Do not accept larger/higher/greater mass.greater van der Waals/dispersion/London forces; 2 (c) Si: giant/network/macromolecular/3-D covalent bonding;No mark for strong bonding without reference to covalent and network.No mark for molecular.Ar: (simple) atomic / (only weak) van der Waals/dispersion/London forces;No mark for (simple) molecular. 2[6] 254. (i) energy/enthalpy change/required/needed to remove/knock out an electron(to form +1 /uni-positive/ M+1 ion);in the gaseous state;Award [1] for M(g) M+(g) + e.Award [2] for M(g) M+(g) + e with reference to energy/enthalpy change. 2 (ii) increasing number of protons/atomic number/Z/nuclear charge;atomic radii/size decreases / same shell/energy level / similar shielding/screening (from inner electrons);No mark for shielding/screening or shielding/screening increases. 2 (iii) Na: delocalized electrons / mobile sea of electrons / sea of electronsfree to move;No mark for just mobile electrons.P: atoms covalently bonded / no free/mobile/delocalized electrons; 2[6] 255. C[1] 256. (i) Na: 11 p, 11/ 2.8.1 e and Na+: 11 p, 10 / 2.8 e / Na+ has 2 shells/energy levels, Na has 3 / OWTTE;Na+: has greater net positive charge/same number of protonspulling smaller number of electrons; 2IB Questionbank Chemistry 63(ii) Si4+: 10 e in 2 (filled) energy levels / electron arrangement2.8 / OWTTE;P3: 18 e in 3 (filled) energy levels / electron arrangement2.8.8, thus larger / OWTTE;ORSi4+: has 2 energy levels whereas P3 has 3 / P3 has one more(filled) energy level;Si4+: 10 e whereas P3 has 18 e / Si4+ has fewer electrons /P3+ has more electrons; 2[4] 257. (i) outer electron in Al is in 3p/p orbital/sub-shell/sub-level;higher orbital/sub-shell / e further from nucleus / shielded by 3s electrons; 2 (ii) in S, electron paired in 3p/p orbital/sub-shell/sub-level;repulsion between paired electrons (and therefore easier to remove); 2[4] 258. D[1] 259. A[1] 260. A[1] 261. B[1] 262. (i) first ionization energy: M(g) M+ (g) +e/e / the (minimum) energy(in kJ mol1) to remove one electron from a gaseous atom / the energyrequired to remove one mole of electrons from one mole of gaseous atoms;periodicity: repeating pattern of (physical and chemical) properties; 2IB Questionbank Chemistry 64(ii) 2.8.8/sp version;Accept any two of the following:the outer energy level/shell is full;the increased charge on the nucleus;great(est) attraction for electrons; 3 max (iii) 17 p in Cl nucleus attract the outer level more than 11 p in Na nucleus /greater nuclear charge attracts outer level more;Allow converse for Na.Do not accept larger nucleus. 1 (iv) S2 has one proton less / smaller nuclear charge so outer level held lessstrongly / OWTTE;Allow converse for chloride.Do not accept larger nucleus. 1 (v) the radii of the metal atoms increase (from Li Cs) (so the forces ofattraction are less between them) / OWTTE;the forces of attraction between halogen molecules are van der Waals;forces increase with increasing mass/number of electrons; 3[10] 263. B[1] 264. C[1] 265. B[1] 266. C[1] 267. B[1] 268. BIB Questionbank Chemistry 65[1] 269. (a) cobalt has a greater proportion of heavier isotopes / OWTTE /cobalt has greater number of neutrons; 1 (b) 27 protons and 25 electrons; 1 (c) 1s22s22p63s23p63d7 / [Ar] 3d7; 1 (d)60Co/Co-60/cobalt-60 and radiotherapy/sterilization of medicalsupplies/radiation treatment of food sterilizations/industrialradiography/density measurements in industry/(medical/radioactive) tracer;Allow treatment of cancer.Do not allow just used in medicine.OR57Co/Co-57/cobalt-57 and medical tests/label for vitamin B12 uptake; 1 maxDo not allow just used in medicine.[4] 270. (a) Group: number of outershell/valence electrons;Period: number of occupied (electron) shells; 2 (b) C: 2 and Si: 3; 1[3] 271. C[1] 272. (i) atomic number / Z;Accept nuclear charge / number of protons. 1IB Questionbank Chemistry 66(ii) Across period 3:increasing number of protons / atomic number / Z / nuclear charge;(atomic) radius/size decreases / same shell/energy level / similarshielding/screening (from inner electrons);No mark for shielding/screening or shielding/screening increases.Noble gases:do not form bonds (easily) / have a full/stable octet/shell/energy level /cannot attract more electrons;Do not accept inert or unreactive without reference to limited ability/inability to form bonds or attract electrons. 3[4] 273. B[1] 274. C[1] 275. C[1] 276. (i) Group: number of valence/outer energy level electrons same;Period: electrons are in same valence/outer energy level;Accept number of energy levels containing electrons occupied.Accept shell for energy level. 2 (ii) 4;Allow the mark if the correct individual orbitals (e.g. 2s etc.) are listed. 1[3] 277. A[1] 278. A[1] IB Questionbank Chemistry 67279. (i) the electron configuration (of argon) / 1s22s22p63s23p6; 1 (ii) x = 1 and y = 5; 1 (iii);4s 3dAccept all six arrows pointing down rather than up. 1[3] 280. B[1] 281. B[1] 282. B[1] 283. 1s22s22p63s1;Do not accept [Ne] 3s1.first electron easy/easiest to remove / 1 electron in outermost/n = 3energy level / furthest from nucleus;large increase between 1st and 2nd IE as electron now removed from n = 2;next 8 electrons more difficult to remove / show (relatively) small increaseas these electrons are in the same energy level/second energy level/n = 2;large increase between 9th and 10th IE as electron now removed from n = 1 / 2electrons very hard/most difficult to remove / innermost/lowest/closest to thenucleus/energy level/n = 1 / OWTTE;electron 11 also comes from 1s, so shows a small increase; 4 max[4] 284. B[1] 285. (i) energy (per mole) needed to remove one/first/most loosely boundIB Questionbank Chemistry 68electron from a (neutral) atom;in the gaseous state;Mg(g) Mg+(g) + e;Gaseous state symbols needed.Accept e instead of e.Only penalize omission of gas phase once in either the second markingpoint or the third marking point. 3 (ii) successive electrons (are more difficult to remove because each is) taken frommore positively charged ion/ OWTTE;increased electrostatic attraction; 2 (iii) 10th electron comes from 2nd energy level/n = 2 and 11th electroncomes from 1st first energy level/n = 1 / OWTTE;electron in 1st energy level closer to nucleus;electron in 1st energy level not shielded by inner electrons /exposed to greater effective nuclear charge; 3[8] 286. C[1] 287. (i)trigonal pyramid;in the range of 100108; 3 (ii)Must include minus sign for the mark.bent/Vshaped;in the range of 100106; 3IB Questionbank Chemistry 69(iii)square planar;90;Penalize once only if electron pairs are missed off outer atoms. 3[9] 288. (i) first ionization energy: M(g) M+ (g) + e/e / the (minimum) energy (inkJ mol1) to remove one electron from a gaseous atom / the energy requiredto remove one mole of electrons from one mole of gaseous atoms;periodicity: repeating pattern of (physical and chemical) properties; 2 (ii) (evidence for main levels)highest values for noble gases / lowest values for alkali metals / OWTTE;general increase across a period;(evidence for sub-levels)drop in I.E. from Be to B/Mg to Al/Group 2 to Group 3;drop in I.E. from N to O/P to S/Group 5 to Group 6; 4 (iii) M+(g) M2+(g) + e/ OWTTE;Accept e instead of e. 1IB Questionbank Chemistry 70(iv) Rough sketch to show:Graph of successive ionization energies for potassiumcorrect use of axes and one electron relatively easy to remove;a jump in value then eight, another jump to another eight and finallyanother jump for the remaining two electrons;electronic configuration of K = 1s22s22p63s23p64s1 / first electron due toremoval of 4s1, next eight due to third level/3s23p6, next eight due tosecond level/2s22p6 and last two due to removal of first level/1s2;the more electrons removed the more the positive nucleus attracts theremaining electrons and each main energy level is closer to thenucleus / OWTTE; 4[11] 289. B[1] 290. D[1] 291. (a) (i) dumbbell-shaped representation along the z-axis:Sign of wave function not required. 1 IB Questionbank Chemistry 71(ii) 1s22s22p63s23p63d5 / 1s22s22p63s23p64s03d5 / [Ar]4s03d5 / [Ar]3d5;Do not allow 2, 8, 13. 1 (iii) Lewis base / (species/ion/molecule) with lone pair and dativecovalent/coordinate bond (to metal) / bonds with metal (ion)/complex ion; 1 (iv) has partially filled d subshell/sublevel/orbitals;d orbitals are split (into two sets of different energies)colour due to electron transition between (split) d orbitals;frequencies of visible light absorbed by electrons moving from lowerto higher d levels, colour due to remaining frequencies;Allow wavelength as well as frequency. 3 max (v)Accept half-arrows or full arrows.Do not penalize if additional sublevels are shown, if sublevels arenot labelled or if no boxes are drawn (providing system ofarrows correct).Do not award mark if sublevels are incorrectly labelled.Orbital diagram may also be represented with sublevels shownat different relative energy positions. 1[7] 292. C[1] 293. D[1] 294. C[1] 295. (a) argon has a greater proportion of heavier isotopes / OWTTE /argon has a greater number of neutrons; 1 (b) 19 protons and 18 electrons; 1 (c) 2, 8, 8; 1IB Questionbank Chemistry 72Accept 1s2 2s2 2p6 3s2 3p6.[3] 296. 2809 = 3.10 30 + 28x + 29(96.9 x);% 28Si = (93 + 2810.1 2809) = 94.1 %; 2Award [2] for correct final answer.[2] 297.14C and radiocarbon dating/(tracer in) medical/scientific tests;11C and (tracer in) medical/scientific tests; 1 max[1] 298. B[1] 299. A[1] 300. B[1] 301. (a) (let x = fraction of 85Rb)100] 87 ) 100 [( ) 85 ( + x x = 85.47;85Rb = 76.5 % and 87Rb = 23.5 %; 2Award [2] for correct final answer.IB Questionbank Chemistry 73(b) the (vaporized) ions are deflected by the (external) magnetic field;the 85Rb /lighter ions are deflected more than the 87Rb/heavierions / OWTTE;Allow deflection depends on mass to charge ratio or momentumof ions.the ions are detected by conversion into an electrical current / OWTTE;the ratio of the intensity of the peaks in the spectrum is equal tothe ratio of the ions in the sample / the ratio of the height of thepeaks due to 85Rb and 87Rb will be 76.5:23.5 / OWTTE; 3 maxIf atoms/elements used instead of ions, penalize only once.Allow the use of sample or isotopes instead of ions. (c) 37 (electrons);50 (neutrons); 2[7] 302. C[1] 303. B[1] 304. D[1] 305. (a) average mass of isotopes of an element compared to (1/12 g of)12 C/ averagemass of an atom relative to C12 having a mass of exactly 12 / OWTTE;Allow element instead of atom.Must refer to average mass and C12. 1IB Questionbank Chemistry 74(b) Diagram of mass spectrometer containing in the correct sequence:vaporization/vaporized sample;ionization/electron gun;acceleration/oppositely charged plates;deflection/magnetic field;detection;Award [3] for 5 correct labels, [2] for 34 correct labels, [1] for 2 correct labels.Award [1] for correct order for at least 4 correct labels.Award [1] for diagram, which must at least show ionization (e.g. electronbeam), acceleration (e.g. charged plates) and deflection (e.g. magneticfield) even if these are incorrectly labelled. 5[6] 306. 63x + 65(1 x) = 63.55;(or some other mathematical expression).63Cu = 72.5 % and 65Cu = 27.5 %;Allow 63Cu = 0.725 and 65Cu = 0.275.Award [2] for correct final answer. 2[2] 307. B[1] 308. D[1] 309. B[1]IB Questionbank Chemistry 75310.showing y-axis labelled as energy/E / labelling at least two energy levels;showing a minimum of four energy levels/lines with convergence;showing jumps to n = 1 for ultraviolet series;showing jumps to n = 2 for visible light series;Must show at least two vertical lines per series to score third and fourth markbut penalize once only.For third and fourth marks if transition not shown from higher to lowerenergy level penalize only once. 4[4] 311. A[1] 312. C[1] 313. (i) ions/particles accelerated by electric field;ions/particles deflected by magnetic field;Award [1 max] for acceleration and deflection of ions withoutreference to fields. 2 (ii) prevents collisions / avoid false readings due to presence of other particles; 1[3]IB Questionbank Chemistry 76314.100) 17 . 2 57 ( ) 88 . 91 56 ( ) 95 . 5 54 ( + + ;55.90;Award [2] for correct final answer.Answer must be to 2 d.p. 2[2] 315. B[1] 316. A[1] 317. (i) a vaporized sample must be used;bombarded with (high energy) electrons to form positive ions;accelerated by passing through an electric field;deflected by passing through a magnetic field;detected by producing a current;Award [2 max] if just the words vaporization, ionization, acceleration,deflection and detection are used with no explanation. 5 (ii) (size of the positive) charge (on the ion);mass (of the ion);strength of the magnetic field;velocity/speed (of the ions) / strength of electric field;m/z scores the first two marking points. 3 max (iii) Ar = 100)] 88 54 . 82 ( ) 87 00 . 7 ( ) 86 90 . 9 ( ) 84 56 . 0 [( + + + ;= 87.71;Award [1 max] if answer not given to two decimal places.Award [2] for correct final answer.Apply 1(U) if answer quoted in g or g mol1. 2[10] 318. A[1]IB Questionbank Chemistry 77319. A[1] 320. D[1] 321. (i) atoms of the same element with the same atomic number/Z/same numberof protons, but different mass numbers/A/different number of neutrons; 1 (ii) (0.9223 28) + (0.0468 29) + (0.0309 30);28.1/28.11;Working must be shown to get [2], do not accept 28.09 on its own (givenin the data booklet). 2 (iii) Silicon dioxidesingle covalent (bonds);network/giant covalent/macromolecular / repeating tetrahedral units;Carbon dioxidedouble covalent (bonds);(simple / discrete) molecular;Marks may be obtained from suitable structural representationsof SiO2 and CO2. 4[7] 322. D[1] 323. A[1] 324. B[1]IB Questionbank Chemistry 78325. series of lines/lines;electron transfer/transition between higher energy level to lower energy level /electron transitions into first energy level causes UV series / transition into secondenergy level causes visible series / transition into third energy level causesinfrared series;convergence at higher frequency/energy/short wavelength;Allow any of the above points to be shown on a diagram. 3[3] 326. A[1] 327. A[1] 328. (a) IV < I < II < III/ultra violet radiation < yellow light < red light < infrared radiation; 1 (b) A continuous spectrum has all colours/wavelengths/frequencies whereasa line spectrum has only (lines of) sharp/discrete/specific colours/wavelengths/frequencies; 1 (c) UV-B radiation has shorter wavelength;hence, has higher energy;increases risk of damage to skin cells / OWTTE / causes cancer; 3[5] 329. A[1] 330. B[1] 331. B[1] 332. CIB Questionbank Chemistry 79[1] 333. C[1] 334. B[1] 335. B[1] 336. B[1] 337. A[1] 338. A[1] 339. B[1] 340. D[1] 341. (a) (i) (10 % 1000 g =) 100 g ethanol and (90 % 1000 g =) 900 g octane; 1 (ii) n(ethanol) = 2.17 mol and n(octane) = 7.88 mol; 1IB Questionbank Chemistry 80(iii) Ereleased from ethanol = (2.17 1367) = 2966 (kJ);Ereleased from octane = (7.88 5470) = 43104 (kJ);total energy released = (2966 + 43104) = 4.61 104 (kJ); 3Award [3] for correct final answer.Accept answers using whole numbers for molar masses and rounding. (b) greater;fewer intermolecular bonds/forces to break / vaporization isendothermic / gaseous fuel has greater enthalpy than liquid fuel / OWTTE; 2M2 cannot be scored if M1 is incorrect.[7] 342. D[1] 343. D[1] 344. D[1] 345. A[1] 346. D[1] 347. C[1] 348. B[1]IB Questionbank Chemistry 81349. D[1] 350. A[1] 351. A[1] 352. (a) (i) Copper:0 to +2 / increases by 2 / +2 / 2+;Allow zero/nought for 0.Nitrogen:+5 to +4 / decreases by 1 / 1 / 1;Penalize missing + sign or incorrect notation such as 2+, 2+or II, once only. 2 (ii) nitric acid/HNO3 / NO3/nitrate;Allow nitrogen from nitric acid/nitrate but not just nitrogen. 1 (b) (i) 0.100 0.0285;2.85 103 (mol);Award [2] for correct final answer. 2 (ii) 2.85 103 (mol); 1 (iii) (63.55 2.85 103) = 0.181 g;Allow 63.5. 1 (iv)

,_

100456 . 0181 . 0 39.7 % 1 (v)

,_

1002 . 447 . 39 2 . 4410/10.2 %;Allow 11.3 % i.e. percentage obtained in (iv) is used todivide instead of 44.2 %. 1IB Questionbank Chemistry 82(c) Brass has:delocalized electrons / sea of mobile electrons / sea of electronsfree to move;No mark for just mobile electrons. 1[10] 353. B[1] 354. B[1] 355. A[1] 356. D[1] 357. (a) n(HCl)(= 0.200 mol dm3 0.02720 dm3) = 0.00544 / 5.44 103 (mol); 1 (b) n(HCl) excess (= 0.100 mol dm3 0.02380 dm3) = 0.00238 /2.38 103 (mol);Penalize not dividing by 1000 once only in (a) and (b). 1 (c) n(HCl) reacted (= 0.00544 0.00238) = 0.00306 / 3.06 103 (mol); 1 (d) 2HCl(aq) + CaCO3(s) CaCl2(aq) + H2O(l) + CO2(g)/2H+(aq) + CaCO3(s) Ca2+(aq) + H2O(l) + CO2(g);Award [1] for correct reactants and products.Award [1] if this equation correctly balanced.Award [1 max] for the following equations:2HCl(aq) + CaCO3(s) CaCl2(aq) + H2CO3(aq)2H+(aq) + CaCO3(s) Ca2+(aq) + H2CO3(aq)Ignore state symbols. 2IB Questionbank Chemistry 83(e) n(CaCO3) = (21n(HCl)) = 21 0.00306; = 0.00153 / 1.53 103 (mol);Award [2] for correct final answer. 2 (f) Mr(CaCO3) (= 40.08 + 12.01 + 3 16.00) = 100.09 /100.1 /M = 100.09 /100.1 (g mol1);Accept 100.m(CaCO3)(= nM) = 0.00153 (mol) 100.09 (g mol1) = 0.153 (g);%CaCO3

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100188 . 0153 . 0= 81.4 % / 81.5 %Accept answers in the range 79.8 to 81.5 %.Award [3] for correct final answer. 3 (g) only CaCO3 reacts with acid / impurities are inert/non-basic / impuritiesdo not react with the acid / nothing else in the eggshell reacts with acid /no other carbonates;Do not accept all calcium carbonate reacts with acid. 1[11] 358. C[1] 359. D[1] 360. D[1] 361. B[1] 362. C[1]IB Questionbank Chemistry 84363. C[1] 364. (a) nC = 01 . 127 . 81 = 6.80 and nH = 01 . 13 . 18 = 18.1;ratio of 1: 2.67 /1: 2.7;C3H8;No penalty for using 12 and 1. 3 (b) C3H8; 1 (c) (i) Br2 /bromine;UV/ultraviolet light;Accept hf/hv/sunlight. 2 (ii) Cr2O72 /MnO4 and acidified/ H+ /H3O+;Accept names.heat / reflux; 2 (d) Initiation:Br2 2Br;Propagation:Br + RCH3 HBr + RCH2;RCH2 + Br2 RCH2Br + Br;Termination: [1 max]Br + Br Br2;RCH2 + Br RCH2Br;RCH2 + RCH2 RCH2CH2R;Award [1] for any termination step.Accept radical with or without throughout.Do not penalize the use of an incorrect alkane in the mechanism. 4 max (e) (i) substitution and nucleophilic and bimolecular/two species inrate-determining step;Allow second order in place of bimolecular. 1IB Questionbank Chemistry 85(ii)curly arrow going from lone pair/negative charge on O in OH to C;Do not allow curly arrow originating on H in OHcurly arrow showing Br leaving;Accept curly arrow either going from bond between C and Br to Br inbromoethane or in the transition state.representation of transition state showing negative charge, squarebrackets and partial bonds;Do not penalize if HO and Br are not at 180 to each other.Do not award M3 if OH ---- C bond is represented unless alreadypenalized in M1.Do not penalize the use of an incorrect alkyl chain in the mechanism. 3[16] 365. C[1] 366. D[1] 367. A[1] 368. C[1] 369. C[1]IB Questionbank Chemistry 86370. B[1] 371. B[1] 372. (a) ester; 1 (b) amount of oil = 6 . 8850 . 1013 = 1.144 mol;amount of methanol = 05 . 320 . 200 = 6.240 mol;since three mol of methanol react with one mol of vegetable oil theamount of excess methanol = 6.204 (3 1.144) = 2.808 mol; 3 (c) (i) rate of the forward reaction is equal to the rate of the reverse reaction /forward and reverse reactions occur and the concentrations of thereactants and products do not change / OWTTE; 1 (ii) Kc = 33[methanol] oil] vegetable [] [biodiesel glycerol] [; 1 (iii) to move the position of equilibrium to the right/product side /increase the yield of biodiesel; 1 (iv) no effect (on position of equilibrium);increases the rate of the forward and the reverse reactions equally(so equilibrium reached quicker) / it lowers Ea for both theforward and reverse reactions by the same amount / OWTTE;No ECF for explanation. 2 (d) vegetable oil is mainly non-polar and methanol is polar / OWTTE;stirring brings them into more contact with each other / increase thefrequency of collisions / OWTTE;Do not allow simply mixing. 2IB Questionbank Chemistry 87(e) (relative molecular mass of biodiesel, C9H36O2 = 296.55)maximum yield of biodiesel = 3.432 mol / 1018 g;percentage yield = 10180 . 811 100 = 79.67 %;Allow 80 % for percentage yield. 2 (f) the carbon dioxide was absorbed by plants initially so there is no netincrease / vegetable oil is not a fossil fuel / vegetable oil is formedfrom (atmospheric) carbon dioxide / OWTTE; 1[14] 373. (a) (i) Fe2+ Fe3+ + e; 1 (ii) MnO4 + 8H+ + 5e Mn2+ + 4H2O; 1 (iii) MnO4 + 5Fe2+ + 8H+ Mn2+ + 5Fe3+ 4H2O;Accept e instead of e. 1 (b) (i) amount of MnO4 = 10006 . 11 0.0200 = 2.32 104 mol; 1 (ii) amount of Fe2+ = 5 2.32 104 = 1.16 103 mol; 1 (iii) mass of Fe2+ = 55.85 1.16 103 = 6.48 102 g;percentage of Fe2+ in tablet = 43 . 110 48 . 62 100 = 4.53 %; 2[7] 374. D[1] 375. C[1]IB Questionbank Chemistry 88376. B[1] 377. D[1] 378. (a) carboxylic acid / carboxyl;ester;Do not allow carbonyl / acid / ethanoate / formula(COOH).aryl group / benzene ring / phenyl; 3 (b) (i) Mr(C7H6O3) = 138.13;n =

,_

13 . 13815 . 32.28 102 (mol);Award [2] for the correct final answer. 2 (ii) Mr(C9H8O4) = 180.17;m = (180.17 2.28 102 =) 4.11(g);Accept range 4.104.14Award [2] for the correct final answer. 2 (iii) (percentage yield = 11 . 450 . 2 100 =) 60.8 %;Accept 6061 %. 1 (iv) 3;(percentage uncertainty = 50 . 202 . 0 100 =) 0.80 %;Allow 0.8 % 2 (v) sample contaminated with ethanoic acid / aspirin not dry /impure sample;Accept specific example of a systematic error.Do not accept error in reading balance/weighing scale.Do not accept yield greater than 100 %. 1[11]IB Questionbank Chemistry 89379. C N O H20.211.4 65.9 2.5012.0114.01 16.00 1.01= 1.68= 0.814 = 4.12 = 2.48 ;

814 . 068 . 1 = 2 814 . 0814 . 0 = 1814 . 012 . 4 = 5 814 . 048 . 2 = 3 ;C2NO5H3;No penalty for use of 12, 1 and/or 14.Award [1 max] if the empirical formula is correct, but no working shown. 3[3] 380. C[1] 381. B[1] 382. D[1] 383. D[1] 384. C[1] 385. (a) MnO4(aq) + 5Fe2+(aq) + 8H+(aq) Mn2+(aq) + 5Fe3+(aq) + 4H2O(l)Award [2] if correctly balanced.Award [1] for correctly placing H+ and H2O.Award [1 max] for correct balanced equation but with electrons shown.Ignore state symbols. 2 (b) Fe2+/ iron(II);Do not accept iron. 1IB Questionbank Chemistry 90(c) n = 2.152 102 2.250 102;4.842 104 (mol);Award [1] for correct volumeAward [1] for correct calculation. 2 (d) 1 mol of MnO4 reacts with 5 mol of Fe2+;5 4.842 104 = 2.421 103 (mol);(same number of moles of Fe in the iron ore)Allow ECF from part (a) and (c) provided some mention of mole ratiois stated. 2 (e) 2.421 103 55.85 = 0.1352(g);3682 . 01352 . 0 100 = 36.72 %;Allow ECF from part (d). 2[9] 386. C[1] 387. D[1] 388. B[1] 389. C[1] 390. C[1] 391. C[1] IB Questionbank Chemistry 91392. (a) 0.600 mol Al(OH)3 (1.5)(0.600) mol H2SO4/0.900 mol H2SO4needed, but only 0.600 mol used;H2SO4 limiting reactant; 2Some working must be shown in order to score the second point. (b) 0.200 mol Al2(SO4)3;68.4(g); 2Penalize incorrect units. (c) 0.200 mol; 1Use ECF from (a). (d) A Brnsted-Lowry acid is a proton/H+ donor;A Lewis base is an electron-pair donor; 2 (e) H2CO3 and carbonic acid / CH3COOH and ethanoic acid; 1Accept any other weak acid and correct formula.[8] 393. empirical formula = CN;Working must be shown to get point.Mr = 51.9 (g mol1);:N CC N:; 3[3]IB Questionbank Chemistry 92