24 (A410U10-1) 24 © WJEC CBAC Ltd. 11. A student carried out two acid-base titrations using two acids, HA and HB. A 25.0 cm3 sample of each acid was titrated against a sodium hydroxide solution of concentration 0.150 mol dm–3 giving the titration curves shown. The initial pH values are missing from both graphs. One acid is a strong acid and one is a weak acid. 0 2 4 6 8 10 12 14 0 5 10 15 20 25 30 35 40 Volume of sodium hydroxide added / cm3 HA pH 0 2 4 6 8 10 12 14 0 5 10 15 20 25 30 35 40 Volume of sodium hydroxide added / cm3 HB pH (A410U10-1) 25 25 © WJEC CBAC Ltd. Turn over. Examiner only (a) Describe and explain the differences between the two curves. • You should identify which acid is strong and which is weak, explaining fully how you have reached your conclusion. • You should identify which acid is more concentrated and which is more dilute, explaining how you have reached your conclusion. [6 QER] (b) Calculate Ka for the weak acid. [2] Ka = ................................................................................... mol dm–3 26 (A410U10-1) 26 Examiner only © WJEC CBAC Ltd. (c) Both these titrations can be performed using appropriate acid-base indicators, but similar experiments using a weak acid and a weak base cannot use acid-base indicators successfully. Explain this difference. [2] (d) The students made 250 cm3 of aqueous sodium hydroxide of concentration 0.150 mol dm–3 for these experiments. (i) Calculate the mass of NaOH required to make this solution. [2] Mass = ....................................................... g (ii) Outline how this solution could be made. [3] (A410U10-1) 27 27 © WJEC CBAC Ltd. Examiner only Turn over. (iii) Calculate the pH of this aqueous sodium hydroxide at 298 K. [3] pH = ....................................................... 18 28 (A410U10-1) 28 © WJEC CBAC Ltd. Examiner only 12. (a) Five ionisation energies are represented by the letters A–E as shown below. A 1st ionisation energy of helium B final ionisation energy of nitrogen C final ionisation energy of oxygen D 1st ionisation energy of sodium E 2nd ionisation energy of magnesium The values of these five ionisation energies are given in the table. Value of ionisation energy / kJ mol–1 Letter representing the ionisation energy 84 078 .................................... 64 360 .................................... 2372 .................................... 1450 .................................... 496 .................................... Complete the table using letters A–E to show which ionisation energy corresponds to each value. Give reasons for your choices. [5] (A410U10-1) 29 29 Examiner only © WJEC CBAC Ltd. Turn over. (b) Three boiling temperatures are listed below. –33°C –111°C –132°C These are the boiling temperatures of NH3, PH3 and AsH3. Identify which value corresponds to each compound. Give reasons for your choices. [3] Boiling temperature of NH3 ..................................................... °C Boiling temperature of PH3 ..................................................... °C Boiling temperature of AsH3 ..................................................... °C 30 (A410U10-1) 30 © WJEC CBAC Ltd. (c) A student is provided with four solutions labelled W, X, Y and Z and is told that these contain common cations and anions that they have studied. He observes that one solution is pale blue and the others are colourless. Flame tests on the solutions give apple-green and golden yellow flames with two solutions and unfamiliar colours with the others. The student mixes pairs of solutions together and obtains the following results. He did not complete all the experiments. Solution 1 Solution 2 Observation(s) W X white precipitate that dissolves when excess solution W is added W Y mixture of pale blue precipitate and white precipitate in a colourless solution W Z no visible change X Y white precipitate in a pale blue solution X Z Y Z white precipitate in a brown solution (A410U10-1) 31 31 © WJEC CBAC Ltd. Turn over. Examiner only Identify the four compounds and give reasons for your decisions. [6] Compound W ................................................................................................................... Compound X ................................................................................................................... Compound Y ................................................................................................................... Compound Z ................................................................................................................... END OF PAPER 14 (A410U10-1) 32 © WJEC CBAC Ltd. 32 Examiner only Question number Additional page, if required. Write the question number(s) in the left-hand margin. BE*(S23-A410U10-1A) © WJEC CBAC Ltd. GCE A LEVEL A410U10-1A MONDAY, 12 JUNE 2023 – 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 S23-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 ▴ ▴▴ ▴ ▴▴