ACSI 2019 Y6 Prelim Paper 2 QP

1 Anglo-Chinese School (Independent) YEAR 6 PRELIMINARY EXAMINATION 2019 INTERNATIONAL BACCALAUREATE DIPLOMA PROGRAMME CHEMISTRY HIGHER LEVEL PAPER 2 Wednesday 18th September 2019 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 /5 Qn 2 /5 Qn 3 /9 Qn 4 /10 Qn 5 /11 Qn 6 /7 Qn 7 /12 Qn 8 /8 Qn 9 /15 Qn 10 /8 Wrong s.f. /units Total /90 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. The lines in the ultraviolet emission spectrum of hydrogen gas converge at 9.12 × 10−8 m. (a) Calculate the ionization energy of hydrogen in kJ mol−1. [2] ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... (b) Sketch on the energy-level diagram below showing the transition that corresponds to the convergence limit that leads to the line with the shortest wavelength in the hydrogen emission spectrum. [1] (This question continues on the following page) wavelength / × 10−8 m Limit 1st line 9.12 9.72 10.26 12.16 Energy n = ∞ n = 7 n = 6 n = 5 n = 4 n = 3 n = 2 n = 1

3 (Question 1 continued) (c) Explain why the convergence limit in the visible spectrum is not used to calculate the ionization energy. [2] ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... 2. Transition metals commonly form coloured complexes. In aqueous solution, nickel(II) sulfate, NiSO4, forms the green hexaaqua nickel(II) complex ion, [Ni(H2O)6]2+(aq). (a) State the type of reaction that takes place between Ni2+ and H2O to form [Ni(H2O)6]2+. [1] ................................................................................................................................... ................................................................................................................................... (b) Complete the table below to show the coordination numbers of the following transition metal complex ions. Complex ion [Ag(NH3)2]+ [CuCl4]2− [Ni(H2O)6]2+ Coordination number [1] (c) Complex ions consist of a central metal ion bonded to ligands. Define the term ligand. [1] ................................................................................................................................... ................................................................................................................................... (This question continues on the following page)

4 (Question 2 continued) (d) When a solution of 1,2-ethanediamine (en) is added to a solution of aqueous nickel(II) sulfate, the colour of the solution changes from green to dark blue and finally to violet as [Ni(en)3]2+ complex ions are formed. With reference to section 17 of the data booklet, deduce with reason the effect of the 1,2-ethanediamine ligand on the splitting of the d-orbitals. [2] ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... 3. (a) Hydrazoic acid, N3H, is an explosive liquid which is usually formed by reacting an azide salt such as NaN3 with a strong acid. N3H can be represented by two possible Lewis structures in which the atoms can be arranged as NNNH. Draw the two possible Lewis (electron dot) structures of N3H and predict the N-N-H bond angle in each structure. [4] Lewis (electron dot) structure Structure I: Structure II: N-N-H bond angle ……………………………………….. ……………………………………….. (This question continues on the following page)

5 (Question 3 continued) (b) The structure of cis-but-2-ene-1,4-dioic acid is shown below. (i) Describe the covalent bond between carbon and hydrogen in the molecule above and how it is formed. [2] ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... ................................................................................................................................... (ii) Deduce the hybridization of the oxygen atoms labelled α and β. [1] α: ................................................................................................................................... β: ................................................................................................................................... (This question continues on the following page)

6 (Question 3 continued) (iii) But-2-ene-1,4-dioic acid can also exist in the trans configuration. Suggest, with reasoning, whether the cis or trans isomer has a higher boiling point. [2] ................................................................................................................................... ............................................................................................................................