ACSI 2018 Prelim Paper 2

1 Anglo-Chinese School (Independent) Year 6 Preliminary Examination 2018 INTERNATIONAL BACCALAUREATE DIPLOMA PROGRAMME CHEMISTRY HIGHER LEVEL PAPER 2 Tuesday 11th September 2018 2 hours 15 minutes INSTRUCTIONS TO CANDIDATES • Do not open this examination paper until instructed to do so. • Write your candidate session number in the box above. • A calculator is required for this paper. • A copy of the Chemistry Data Booklet is required for this paper. • Write your answers in the boxes provided. • If you use additional sheets of paper for your answer, attach them to the booklet. Indicate the question number clearly on these sheets. 0 0 2 3 2 9 For examiner’s use Qn 1 /6 Qn 2 /11 Qn 3 /5 Qn 4 /18 Qn 5 /9 Qn 6 /11 Qn 7 /11 Qn 8 /15 Qn 9 /9 Wrong s.f. /units Total /95 Candidate Session Number ________________________________________________________________________ This question paper consists of 22 printed pages including this cover page.

2 Answer all questions. Write your answers in the boxes provided. 1. (a) The emission spectrum of hydrogen is shown in the diagram below. (i) Describe the emission spectrum of hydrogen. [2] (ii) State an electron transition that corresponds to a line in the visible emission spectrum. [1] (b) The first seven ionization energies of an atom, X, in kJ mol−1, are 1012 1903 2912 4957 6274 21 269 25 298 (i) Write the electronic configuration of element X which belongs to Period 3. [1] (This question continues on the following page) High energy Low energy

3 (Question 1 continued) (ii) Explain the general increase in the ionization energy values. [2] 2. The halogens form many interhalogen compounds and ions with other halogen atoms. Two such species are ClF5 and ICl4 −. (a) Draw the Lewis (electron dot) structures of ClF5 and ICl4 − and state their molecular geometry. [4] Molecular Geometry: Molecular Geometry: (This question continues on the following page)

4 (Question 2 continued) (b) A student proposed the two possible shapes for the C lF3 molecule were trigonal planar and T-shape. He did some research and learnt that the molecule has an overall dipole moment. Which of the two shapes is consistent with the fact that the C lF3 molecule has an overall dipole moment? Justify your answer in terms of bond polarity and molecular geometry. [2] (c) (i) The following exergonic equilibrium gives rise to triiodide ion: I2 + I− ⇌ I3− Explore if the reaction is an acid-base reaction. [2] (ii) Explain with reference to its atomic structure, why the magnitude of the electron affinity of iodine is lower than fluor