26 (A410U10-1) 26 © WJEC CBAC Ltd. 13. The elements of Group 5 react with hydrogen to form compounds of formula XH3. Some information regarding the physical properties of these compounds is shown in the table. Compound Formula Boiling temperature / °C Solubility in water / g dm–3 ammonia NH3 –33 470 phosphane PH3 –83 0.312 arsane AsH3 –63 0.710 stibane SbH3 –17 4.24 (a) Identify and explain the patterns seen in these physical properties. [6 QER] Examiner only (A410U10-1) Turn over. 27 27 Examiner only © WJEC CBAC Ltd. (b) Use VSEPR theory to predict the shape of the PH3 molecule, giving reasons for your answer. [3] 28 (A410U10-1) 28 © WJEC CBAC Ltd. (c) Stibane is a gas that decomposes slowly at a temperature of 350 °C. 2Sb(s) 3H2(g) 2SbH3(g) + The decomposition of stibane was studied in a sealed vessel, with the pressure measured over a period of 100 hours. The results are shown on the graph. 40 000 42 000 44 000 46 000 48 000 50 000 52 000 54 000 56 000 58 000 60 000 0 10 20 30 40 50 60 70 80 90 100 Gas pressure / Pa Time / hours (A410U10-1) Turn over. 29 29 Examiner only © WJEC CBAC Ltd. (i) The initial pressure in the vessel was 42 000 Pa. Calculate the pressure in the vessel when all the stibane had decomposed. [2] Pressure = ...................................................... Pa (ii) Calculate the initial rate of change of pressure in Pa hr –1. [2] Rate of change of pressure = ...................................................... Pa hr –1 (iii) Use the initial pressure and your answer to part (i) to calculate the pressure in the vessel when half the stibane had decomposed. Use this and the graph to show that the reaction is first order with respect to stibane. [4] Pressure when half the stibane had decomposed = ...................................................... Pa 30 (A410U10-1) 30 © WJEC CBAC Ltd. Examiner only (d) Ammonia is produced industrially using the Haber process. 3H2(g) N2(g) + 2NH3(g) The reaction traditionally used iron-based catalysts which reduce the activation energy of the reaction to 101.4 kJ mol–1. Newer catalysts have been developed using ruthenium which reduce the activation energy further to 64.0 kJ mol–1. (i) These are examples of heterogeneous catalysts. State what is meant by a ‘heterogeneous’ catalyst. [1] (ii) State, giving a reason, the effect of changing the catalyst on the position of this equilibrium. [2] (A410U10-1) Turn over. 31 31 © WJEC CBAC Ltd. Examiner only (iii) The Haber process typically uses a temperature of 500 °C. Replacing the iron-based catalyst with a newer ruthenium-based catalyst increases the initial rate of reaction by a factor, f, at this temperature. Use the Arrhenius equation to calculate the value of f. You may assume that the frequency factor in both cases is the same. [3] f = ...................................................... 32 (A410U10-1) 32 © WJEC CBAC Ltd. (e) When water is added to gaseous phosphane no visible reaction occurs. However, studies using isotopes of hydrogen have shown that hydrogen atoms are exchanged between the phosphane and water. The following gas phase equilibrium occurs, where D represents deuterium, a hydrogen isotope with a mass number of 2. H2O(g) PH2D(g) + HDO(g) + PH3(g) A sealed vessel of volume 500 cm3 contained 1.00 × 10–3 mol of PH2D(g). A sample of 4.90 × 10–4 mol of H2O(g) was added and the mixture allowed to reach equilibrium. The mass spectrum of the equilibrium mixture shows that 36% of the phosphorus is present in PH3 and 64% of the phosphorus is present in PH2D. Calculate the value of the equilibrium constant Kc for this reaction. [4] Kc = ...................................................................... END OF PAPER 27 Examiner only (A410U10-1) Turn over. 33 © WJEC CBAC Ltd. 33 Examiner only Question number Additional page, if required. Write the question number(s) in the left-hand margin. 34 (A410U10-1) © WJEC CBAC Ltd. 34 Question number Additional page, if required. Write the question number(s) in the left-hand margin. Examiner only (A410U10-1) 35 © WJEC CBAC Ltd. 35 BLANK PAGE PLEASE DO NOT WRITE ON THIS PAGE 36 (A410U10-1) © WJEC CBAC Ltd. 36 BLANK PAGE PLEASE DO NOT WRITE ON THIS PAGE BE*(S22-A410U10-1A) © WJEC CBAC Ltd. GCE A LEVEL A410U10-1A MONDAY, 13 JUNE 2022 – MORNING CHEMISTRY – A level component 1 Data Booklet Avogadro constant NA = 6.02 × 1023 mol –1 molar gas constant R = 8.31 J mol –1 K –1 molar gas volume at 273 K and 1 atm Vm = 22.4 dm3 mol –1 molar gas volume at 298 K and 1 atm Vm = 24.5 dm3 mol –1 Planck constant h = 6.63 × 10 –34 J s speed of light c = 3.00 × 108 m s –1 density of water d = 1.00 g cm –3 specific heat capacity of water c = 4.18 J g –1 K –1 ionic product of water at 298 K Kw = 1.00 × 10 –14 mol 2 dm – 6 fundamental electronic charge e = 1.60 × 10 –19 C temperature (K) = temperature (°C) + 273 1 dm3 = 1000 cm3 1 m3 = 1000 dm3 1 tonne = 1000 kg 1 atm = 1.01 × 105 Pa Multiple Prefix Symbol 10 –9 nano n 10 –6 micro μ 10 –3 milli m Multiple Prefix Symbol 10 3 kilo k 10 6 mega M 10 9 giga G Z22-A410U10-1A (A410U10-1A) 2 © WJEC CBAC Ltd. 500 to 600 650 to 800 1000 to 1300 1620 to 1670 1650 to 1750 2100 to 2250 2800 to 3100 2500 to 3200 (very broad) 3200 to 3550 (broad) 3300 to 3500 C Br C Cl C O C C C O C N C H O H (carboxylic acid) O H (alcohol / phenol) N H 10 to 70 5 to 40 20 to 50 25 to 60 50 to 90 90 to 150 110 to 125 110 to 160 160 to 185 190 to 220 N C R C C C O C C R Cl or Br C O C R C O (carboxylic acid / ester) C R (aldehyde / ketone) O C R N R C 13C NMR chemical shifts relative to TMS = 0 Type of carbon Chemical shift, δ (ppm) Infrared absorption values Bond Wavenumber / cm –1 Turn over. (A410U10-1A) 3 © WJEC CBAC Ltd. *variable figure dependent on concentration and solvent 1H NMR chemical shifts relative to TMS = 0 Type of proton Chemical shift, δ (ppm) 0.9 0.1 to 2.0 3.1 to 4.3 1.3 2.0 2.0 to 3.0 2.0 to 2.5 2.2 to 2.3 R CH3 R CH2 R CH3 C N CH3 C O CH3 CH3 CH2 C O 4.5 * 4.5 to 6.3 6.5 to 7.5 6.5 to 8.0 R OH 3.3 to 4.3 HC Cl or HC Br C CH HC O C CH H 7.0 * OH 9.8 * 11.0 * R C O H R C O OH 5.8 to 6.5 C CH CO (A410U10-1A) 4 © WJEC CBAC Ltd. 6.94 Li Lithium 3 9.01 Be Beryllium 4 10.8 B Boron 5 12.0 C Carbon 6 14.0 N Nitrogen 7 16.0 O Oxygen 8 19.0 F Fluorine 9 20.2 Ne Neon 10 23.0 Na Sodium 11 24.3 Mg Magnesium 12 27.0 Al Aluminium 13 28.1 Si Silicon 14 31.0 P Phosphorus 15 32.1 S Sulfur 16 35.5 Cl Chlorine 17 40.0 Ar Argon 18 39.1 K Potassium 19 40.1 Ca Calcium 20 45.0 Sc Scandium 21 47.9 Ti Titanium 22 50.9 V Vanadium 23 52.0 Cr Chromium 24 54.9 Mn Manganese 25 55.8 Fe Iron 26 58.9 Co Cobalt 27 58.7 Ni Nickel 28 63.5 Cu Copper 29 65.4 Zn Zinc 30 69.7 Ga Gallium 31 72.6 Ge Germanium 32 74.9 As Arsenic 33 79.0 Se Selenium 34 79.9 Br Bromine 35 83.8 Kr Krypton 36 85.5 Rb Rubidium 37 87.6 Sr Strontium 38 88.9 Y Yttrium 39 91.2 Zr Zirconium 40 92.9 Nb Niobium 41 95.9 Mo Molybdenum 42 98.9 Tc Technetium 43 101 Ru Ruthenium 44 103 Rh Rhodium 45 106 Pd Palladium 46 108 Ag Silver 47 112 Cd Cadmium 48 115 In Indium 49 119 Sn Tin 50 122 Sb Antimony 51 128 Te Tellurium 52 127 I Iodine 53 131 Xe Xenon 54 133 Cs Caesium 55 137 Ba Barium 56 139 La Lanthanum 57 179 Hf Hafnium 72 181 Ta Tantalum 73 184 W Tungsten 74 186 Re Rhenium 75 190 Os Osmium 76 192 Ir Iridium 77 195 Pt Platinum 78 197 Au Gold 79 201 Hg Mercury 80 204 Tl Thallium 81 207 Pb Lead 82 209 Bi Bismuth 83 (210) Po Polonium 84 (210) At Astatine 85 (222) Rn Radon 86 (223) Fr Francium 87 (226) Ra Radium 88 (227) Ac Actinium 89 THE PERIODIC TABLE 1 2 Group 3 4 5 6 7 0 1 2 3 4 5 6 7 1.01 H Hydrogen 1 4.00 He Helium 2 d block s block Period p block 140 Ce Cerium 58 141 Pr Praseodymium 59 144 Nd Neodymium 60 (147) Pm Promethium 61 150 Sm Samarium 62 (153) Eu Europium 63 157 Gd Gadolinium 64 159 Tb Terbium 65 163 Dy Dysprosium 66 165 Ho Holmium 67 167 Er Erbium 68 169 Tm Thulium 69 173 Yb Ytterbium 70 175 Lu Lutetium 71 232 Th Thorium 90 (231) Pa Protactinium 91 238 U Uranium 92 (237) Np Neptunium 93 (242) Pu Plutonium 94 (243) Am Americium 95 (247) Cm Curium 96 (245) Bk Berkelium 97 (251) Cf Californium 98 (254) Es Einsteinium 99 (253) Fm Fermium 100 (256) Md Mendelevium 101 (254) No Nobelium 102 (257) Lr Lawrencium 103 f block Actinoid elements Ar Symbol Name Z relative atomic mass atomic number Key Lanthanoid elements ▴ ▴▴ ▴ ▴▴