Chemistry 9701/23 May/June 2022: question paper and mark scheme

Question

(a) Define first ionisation energy. …… [2] (b) Successive ionisation energies for element A are shown in Table 1.1. Table 1.1 ionisation 1st 2nd 3rd 4th 5th 6th 7th 8th ionisation 1310 3390 5320 7450 11 000 13 300 71 000 84 100 energy / kJ mol–1 Use Table 1.1 to deduce the group of the Periodic Table that A belongs to. Explain your answer. Group …… [1] (c) Across Period 3 there is a general trend for first ionisation energies to increase due to the increase in attraction between the nucleus and the outer electron. Explain why the first ionisation energy of sulfur is less than the first ionisation energy of phosphorus. …… [2] (d) In an Al 2+ ion the nuclear attraction for the outer electron is stronger than in an atom of Na. Compare the electronic structures of Al 2+ and an atom of Na and explain why the third ionisation energy of aluminium is greater than the first ionisation energy of sodium. …… [2] (e) An isotope of copper has a relative isotopic mass of 65. Complete Table 1.2 for an atom of copper-65. Table 1.2 atomic nucleon number electronic arrangement number number of neutrons copper-65 [3] (f) (i) The element copper has a relative atomic mass of 63.5. Calculate how many atoms are present in 1.05 g of copper. atoms of copper present = …… [1] (ii) Copper has a melting point of 1085 °C and a high electrical conductivity. Explain these properties of copper by referring to its structure and bonding. . …… . …… . …… [2] [Total: 13]

Question

(a) Period 3 elements and their compounds show trends in their physical properties. (i) On Fig. 2.1 sketch a graph to show the melting points of the first five elements in Period 3. melting point Na Mg Al Si P Fig. 2.1 [3] (ii) Complete Table 2.1 with information for sodium chloride and phosphorus(V) chloride. Table 2.1 sodium chloride phosphorus(V) chloride state at room temperature name of change which occurs on addition of water pH of final solution [3] (b) Tennessine, Ts, is an unstable man-made element. It is found below astatine, At, in Group 17. The chemical properties of Ts and its compounds have only been predicted. (i) Suggest an equation for the reaction of NaTs and Br2. Assume that Ts follows the same trends as the other elements in Group 17. Explain your answer. equation . …… explanation …… . …… [2] (ii) Some scientists predict that Ts has properties typical of metals like copper. Complete Table 2.2 with: ● the predicted melting point of tennessine ● the lattice structure of solid chlorine, bromine and tennessine. Assume that Ts has properties typical of metals like copper. Table 2.2 element chlorine bromine tennessine melting point / °C –101 –7.2 lattice structure of crystalline solid [2] [Total: 10]

Question

G belongs to a group of compounds called ethers. G H H H H H C C O C C H H H H H Fig. 3.1 (a) When G, C4H10O, is heated, thermal decomposition occurs. C4H10O(g) → C2H6(g) + CO(g) + CH4(g) ∆H = –7.00 kJ mol–1 (i) The atoms in a molecule of CO are held together by a triple covalent bond. One of these bonds is a coordinate (dative covalent) bond. Draw a dot-and-cross diagram to show the arrangement of outer electrons in a CO molecule. Use ● to represent electrons from an oxygen atom. Use × to represent electrons from a carbon atom. [1] (ii) Calculate the bond energy of C≡O using the bond energy values in Table 3.1 and the enthalpy change, ∆H, for the thermal decomposition of G. Show your working. Table 3.1 bond bond energy / kJ mol–1 C–C 350 C–O (in G) 360 C–H 410 bond energy (C≡O) = …… kJ mol–1 [2] (iii) When G, C4H10O, is heated in a sealed container, an equilibrium mixture is produced. C4H10O(g) C2H6(g) + CO(g) + CH4(g) Complete the expression for the equilibrium constant, Kc, for this reaction. State the units of Kc. Kc = units = …… [2] (iv) Thermal decomposition of G in the presence of I2 affects the activation energy, Ea, for the reaction. Table 3.2 shows Ea for the thermal decomposition of G with and without I2. Table 3.2 reaction Ea (with I2) / kJ mol–1 Ea / kJ mol–1 C4H10O(g) → C2H6(g) + CO(g) + CH4(g) 143 224 State what effect adding I2 to the reaction mixture has on the value of Kc. Explain your answer. . …… . …… . …… . …… [2] (v) Fig. 3.2 shows the Boltzmann distribution of energies for molecules of G at constant temperature, T °C. Sketch, on Fig. 3.2, the Boltzmann distribution of energies for molecules of G at a higher temperature, (T+100) °C. number of molecules Ea energy Fig. 3.2 [2] (b) The functional group in G is an oxygen atom bonded to two carbon atoms. G H H H H H C C O C C H H H H H Fig. 3.3 G, H and J are structural isomers with molecular formula C4H10O. H and J are straight chain molecules. Table 3.3 shows the boiling points and reactions of G, H and J when heated under reflux with excess acidified K2Cr2O7. Table 3.3 G H J boiling point / °C 35 117 98 heat under reflux with remains orange orange to green orange to green excess acidified K2Cr2O7 (i) Identify the type of structural isomerism shown between G and H using the information in Table 3.3. . …… [1] (ii) Identify the type of structural isomerism shown between H and J using the information in Table 3.3. . …… [1] (iii) Draw a possible structure for H and for J. State the systematic name for each structure. H J name …… name …… [3] (c) K has molecular formula C3H6O. When K is added to 2,4-dinitrophenylhydrazine, an orange precipitate forms. When K is warmed with Tollens’ reagent, a silver mirror forms. Draw the displayed formula of K. K [2] [Total: 16]

Question

(a) 2-methylpropene reacts with HCl (g) at room temperature. The major organic product is 2-chloro-2-methylpropane. (i) Complete Fig. 4.1 to show the structure of the intermediate and mechanism for this reaction. Include charges, dipoles, lone pairs of electrons and curly arrows as appropriate. H 3C H CH3 Cl C C C CH3 H 3C H H 3C H Cl Fig. 4.1 [3] (ii) Explain why, in this reaction, 2-chloro-2-methylpropane is produced at a higher yield than 1-chloro-2-methylpropane. . …… . …… . …… [2] (b) Two bottles labelled Q and M each contain a straight-chain halogenoalkane with molecular formula C4H9X, where X represents Cl, Br or I. A sample from each bottle is added to separate samples of equal amounts of aqueous silver nitrate in ethanol. In each reaction, the same organic product, T, and a precipitate are made, as shown in Fig. 4.2. AgNO3(aq) in ethanol AgNO3(aq) in ethanol Q T M Fig. 4.2 Table 4.1 describes the colour of each of the precipitates made. Table 4.1 halogenoalkane added colour of precipitate to AgNO3(aq) in ethanol Q white M yellow (i) Identify the functional group present in T and name the type of reaction that occurs using the information in Fig. 4.2 and Table 4.1. functional group in T …… type of reaction …… [2] (ii) Construct an ionic equation to describe the formation of the yellow precipitate produced when M reacts with AgNO3(aq) in ethanol. . …… [1] (iii) Describe which reagent, Q or M, will produce a precipitate more quickly when each is added to AgNO3(aq) in ethanol. Explain your answer. reagent …… . …… . …… [1] (iv) When pure T is added to alkaline I2(aq), a yellow precipitate and an anion, L, are made. Identify the anion L. . …… [1] (v) Deduce the structure of the straight-chain halogenoalkane M. [2] [Total: 12]

Question

(a) But-2-ene reacts with KMnO4 to form organic product, Y. Y does not react with Na2CO3. A gas is produced when an excess of Na is added to Y. (i) Describe the conditions for the KMnO4 used in the reaction to form Y from but-2-ene. . …… [1] (ii) 24.0 cm3 of gas is produced when an excess of Na is added to 0.001 mol of Y, when measured under room conditions. Assume that 1 mol of gas occupies 24.0 dm3 under room conditions. Deduce a possible structure of Y. Explain your answer. . …… . …… . …… [3] (b) Z contains three types of atom: carbon, hydrogen and a halogen. The mass spectrum of Z is recorded. Fig. 5.1 shows a section of the mass spectrum at m/e greater than 63. The fragment at m/e = 64 is the molecular ion peak. 100 100 80 relative 60 abundance 40 33.3 20 2.2 0 63 64 65 66 67 m/e Fig. 5.1 (i) Deduce the number of carbon atoms present in a molecule of Z using Fig. 5.1. Show your working. . …… [1] (ii) Deduce which halogen is present in Z using Fig. 5.1. Explain your answer. . …… . …… [1] (iii) There are also peaks at m/e = 29 and m/e = 49. Suggest the formulae of these fragments. Deduce the name of Z. m/e = 29 …… m/e = 49 …… name of Z …… [3] [Total: 9] Important values, constants and standards molar gas constant R = 8.31 J K–1 mol–1 Faraday constant F = 9.65 × 104 C mol–1 Avogadro constant L = 6.022 × 1023 mol–1 electronic charge e = –1.60 × 10–19 C molar volume of gas Vm = 22.4 dm3 mol–1 at s.t.p. (101 kPa and 273 K) Vm = 24.0 dm3 mol–1 at room conditions ionic product of water Kw = 1.00 × 10–14 mol2 dm–6 (at 298 K (25 °C)) specific heat capacity of water c = 4.18 kJ kg–1 K–1 (4.18 J g–1 K–1) The Periodic Table of Elements Group 1 2 13 14 15 16 17 18 1 2 H He hydrogen helium Key 1.0 4.0 3 4 atomic number 5 6 7 8 9 10 Li Be atomic symbol B C N O F Ne lithium beryllium name boron carbon nitrogen oxygen fluorine neon 6.9 9.0 relative atomic mass 10.8 12.0 14.0 16.0 19.0 20.2 11 12 13 14 15 16 17 18 Na Mg Al Si P S Cl Ar sodium magnesium aluminium silicon phosphorus sulfur chlorine argon 23.0 24.3 3 4 5 6 7 8 9 10 11 12 27.0 28.1 31.0 32.1 35.5 39.9 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 at www.cambridgeinternational.org after the live examination series. K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr potassium calcium scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc gallium germanium arsenic selenium bromine krypton 39.1 40.1 45.0 47.9 50.9 52.0 54.9 55.8 58.9 58.7 63.5 65.4 69.7 72.6 74.9 79.0 79.9 83.8 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 16 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe rubidium strontium yttrium zirconium niobium molybdenum technetium ruthenium rhodium palladium silver cadmium indium tin antimony tellurium iodine xenon 85.5 87.6 88.9 91.2 92.9 95.9 – 101.1 102.9 106.4 107.9 112.4 114.8 118.7 121.8 127.6 126.9 131.3 55 56 57–71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 lanthanoids Cs Ba Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn caesium barium hafnium tantalum tungsten rhenium osmium iridium platinum gold mercury thallium lead bismuth polonium astatine radon 132.9 137.3 178.5 180.9 183.8 186.2 190.2 192.2 195.1 197.0 200.6 204.4 207.2 209.0 – – – 87 88 89–103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 actinoids Fr Ra Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og francium radium rutherfordium dubnium seaborgium bohrium hassium meitnerium darmstadtium roentgenium copernicium nihonium flerovium moscovium livermorium tennessine oganesson – – – – – – – – – – – – – – – – – 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 lanthanoids La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu lanthanum cerium praseodymium neodymium promethium samarium europium gadolinium terbium dysprosium holmium erbium thulium ytterbium lutetium 138.9 140.1 140.9 144.4 – 150.4 152.0 157.3 158.9 162.5 164.9 167.3 168.9 173.1 175.0 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 actinoids Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr actinium thorium protactinium uranium neptunium plutonium americium curium berkelium californium einsteinium fermium mendelevium nobelium lawrencium – 232.0 231.0 238.0 – – – – – – – – – – – Assessment International Education Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge