13028 16 Oxalic acid is a weak acid which can form a hydrated salt, (COOH)2.xH2O. (a) Explain what is meant by the term hydrated. [1] (b) Explain what is meant by a weak acid. [1] (c) The value of x in (COOH)2.xH2O may be found by titration with a standard solution of sodium hydroxide. 1.60 g of the hydrated oxalic acid were dissolved in 250 cm3 of distilled water. 25.0 cm3 of the solution were transferred to a conical flask. A suitable indicator was added. 25.4 cm3 of 0.100 mol dm-3 sodium hydroxide solution were needed for neutralisation. The equation for the reaction is: (COOH)2  +  2NaOH  →  (COONa)2  +  2H2O (i) Suggest a suitable indicator and state the colour change at the endpoint. Indicator: From:                             to                               [3] 13028 THIS IS THE END OF THE QUESTION PAPER (ii) Calculate the mass of oxalic acid (COOH)2 in the 250 cm3 of solution. Give your answer to two decimal places. [3] (iii) Calculate the value of x in the formula (COOH)2.xH2O. [3] Permission to reproduce all copyright material has been applied for. In some cases, efforts to contact copyright holders may have been unsuccessful and CCEA will be happy to rectify any omissions of acknowledgement in future if notified. DO NOT WRITE ON THIS PAGE SCH14/6 260544 For Examiner’s use only Question Number Marks Section A 1–10 Section B 11 12 13 14 15 16 Total Marks Data Leafl et Including the Periodic Table of the Elements For the use of candidates taking Advanced Subsidiary and Advanced Level Examinations Copies must be free from notes or additions of any kind. No other type of data booklet or information sheet is authorised for use in the examinations gce a/as examinations chemistry © CCEA 2017 General Information 1 tonne = 106 g 1 metre = 109 nm One mole of any gas at 293 K and a pressure of 1 atmosphere (105 Pa) occupies a volume of 24 dm3 Avogadro Constant = 6.02 × 1023 mol–1 Planck Constant = 6.63 × 10–34 J s Specifi c Heat Capacity of water = 4.2 J g–1 K–1 Speed of Light = 3 × 108 m s–1 Characteristic absorptions in IR spectroscopy Wavenumber/cm–1 Bond Compound 550–850 C–X (X = Cl, Br, I) Haloalkanes s p u o r g ly kla ,s e n a kl A C – C 0 0 1 1 – 0 5 7 s dic a cily x o b r a c ,sr e ts e ,slo h o cl A O – C 0 0 3 1 – 0 0 0 1 1450–1650 C ̿ s e n e r A C 1600–1700 C ̿ s e n e kl A C 1650–1800 C ̿ ,s e d y h e dla ,sr e ts e ,s dic a cily x o b r a C O s e dir olh c ly c a ,s e di m a ,s e n o t e k 2200–2300 C s elirti N N s dic a cily x o b r a C H – O 0 0 2 3 – 0 0 5 2 s e d y h e dl A H – C 0 5 8 2 – 0 5 7 2 s e n e r a ,s e n e kla ,s p u o r g ly kla ,s e n a kl A H – C 0 0 0 3 – 0 5 8 2 slo h o cl A H – O 0 0 6 3 – 0 0 2 3 s e di m a ,s e ni m A H – N 0 0 5 3 – 0 0 3 3 Proton Chemical Shifts in Nuclear Magnetic Resonance Spectroscopy (relative to TMS) Structure 0.5–2.0 –CH s e n a kla d e t a r u t a S 0.5–5.5 –OH slo h o cl A 1.0–3.0 –NH s e ni m A 2.0–3.0 –CO–CH Ketones C – N – H Amines C 6H5–CH c on ring) 2.0–4.0 X–CH X = Cl or Br (3.0–4.0) ) 0.3 – 0.2 ( I = X 4.5–6.0 –C ̿ CH Alkenes 5.5–8.5 RCONH Amides 6.0–8.0 –C6H5 Arenes (on ring) 9.0–10.0 –CHO Aldehydes 10.0–12.0 –COOH Carboxylic acids on and temperature dependent and may be outside the ranges indicated above. 11331.03 227 89 139 57 256 101 223 87 226 88 261 104 262 105 266 106 264 107 277 108 268 109 271 110 272 111 140 58 141 59 144 60 145 61 150 62 152 63 157 64 159 65 162 66 165 67 167 68 169 69 173 70 175 71 232 90 231 91 238 92 237 93 242 94 243 95 247 96 245 97 251 98 254 99 253 100 254 102 257 103 133 55 137 56 178 72 181 73 184 74 186 75 190 76 192 77 195 78 197 79 201 80 89 39 91 40 103 45 85 37 88 38 93 41 96 42 98 43 101 44 106 46 108 47 112 48 131 54 222 86 210 85 210 84 209 83 207 82 204 81 84 36 79 34 73 32 40 20 39 19 45 21 48 22 51 23 52 24 55 25 56 26 59 27 59 28 64 29 65 30 11 5 12 6 14 7 16 8 19 9 20 10 4 2 40 18 35.5 17 32 16 31 15 28 14 27 13 70 31 75 33 80 35 115 49 119 50 122 51 128 52 127 53 23 11 24 12 7 3 9 4 THE PERIODIC TABLE OF ELEMENTS Group * † 1 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 II I III IV VI VII 0 V 285 112 Copernicium * 58 – 71 Lanthanum series † 90 – 103 Actinium series a = relative atomic mass x = atomic symbol b = atomic number a bx (approx) 11331.03