YJC_H2_CHEM_P1_Worked_Solution.pdf

YJC_H2_CHEM_P1_Worked_Solution.pdf - 2017 JC2 H2 Chemistry...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
2017 JC2 H2 Chemistry 9729 Preliminary Examinations Paper 1 Worked Solutions Page 1 of 5 Paper 1 Worked Solutions 1 A 2 C 3 B 4 B 5 B 6 C 7 D 8 D 9 D 10 B 11 D 12 B 13 C 14 C 15 A 16 D 17 A 18 C 19 C 20 B 21 B 22 A 23 D 24 A 25 D 26 C 27 D 28 A 29 D 30 A 1 MnO 4 + 8H + + 5e Mn 2+ + 4H 2 O 0.004 mol MnO 4 gains 0.004 × 5 = 0.020 mol of e . 0.01 mol R 2+ loses 0.020 mol of e . 1 mol R 2+ loses 2 mol of e . O.S. of R increases from +2 to +4. Ans: A 2 A : Incorrect. The equation corresponds to the sum of 1 st , 2 nd and 3 rd I.E. B : Incorrect. Ti 2+ needs to be in gaseous state, not solid state. C : Correct. Third ionisation of Ti is the energy required to remove one mole of electrons from one mole of Ti 2+ (g) to form one mole of Ti 3+ (g). D : Incorrect. The equation corresponds to the reverse of 3 rd I.E. Ans: C 3 1 : Correct. B 2− has an electronic configuration of 1s 2 2s 2 2p 3 . 2 : Correct. C has an electronic configuration of 1s 2 2s 2 2p 3 . 3 : Incorrect. N has an electronic configuration of 1s 2 2s 2 2p 4 . 4 : Correct. N has an electronic configuration of 1s 2 2s 2 2p 3 . Ans: B 4 As all four gases consist of non-polar molecules (the dipole moments cancel out completely in SO 3 as it has a trigonal planar shape), only id-id interactions exist between their respective molecules. Since SO 3 has the biggest and most polarisable electron cloud, the id-id interaction between its molecules is the strongest (and the volume of its molecules will be the most significant compared to the volume of the container), and so SO 3 shows the greatest deviation from ideality among the 4 gases. Ans: B 5 1 1 1 2 2 2 1 1 2 2 1 2 Rearranging, pV nRT p V nRT pV p V nR T T 2 1 P ( V) (4.50)V 3 298 753 P 2 = 34.1 atm Ans: B 6 As pressure increases, equilibrium position will shifts to the side with a smaller number of moles of gas to reduce pressure; and as seen from the graph, percentage of the product decreases. This implies that the reactants contain fewer moles of gas than the products (option B or C ). When temperature is increased from T °C to (T + 20) °C, the endothermic reaction will occur to a greater extent to remove heat; and as seen from the graph, percentage of the product decreases. This implies that the forward reaction is exothermic (option A or C ). Ans: C 7 K w = [H + ] [OH ] (by definition) At 50 °C, K w = 5.48 × 10 14 mol 2 dm 6 [H + ] [OH ] = 5.48 × 10 14 mol 2 dm 6 Since [H + ] = [OH ] for pure water, [H + ] 2 = 5.48 × 10 14 mol 2 dm 6 [H + ] = 2.34 × 10 7 mol dm 3 pH = −log [H + ] = −log (2.34 × 10 7 ) = 6.63 (< 7) Answer: D 8 For a weak acid-weak base (methylamine) titration, the pH will change gradually as the titrant is added to the aliquot even when it is near to the equivalence point (i.e.no sharp colour change will be observed), and so there is no suitable indicator that can be used for the titration.
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern