MJC_2008 H1 Chem Prelim Paper 2 (Questions)

Class Reg Number Candidate Name ___________________________________ Meridian Junior College JC2 Preliminary Examinations 2008 H1 Chemistry 8872 Paper 2 11 September 2008 2 hours INSTRUCTION TO CANDIDATES Write your name, class and register number in the spaces at the top of this page. This booklet contains Section A and B of your paper. Section A (Pg 1-11) Answer ALL questions in Section A in the spaces provided on the question paper. You are advised to spend about 1 hour on Section A. Section B (Pg 12-17) Answer two out of three questions in Section B on the foolscap paper. You are advised to spend about 1 hour on Section B. Begin each question on a fresh page of writing paper. Fasten your answers for Section B behind Section A. You are advised to spend about 30 min per question. INFORMATION FOR CANDIDATES The number of marks is given in brackets [ ] at the end of each question or part question. This question paper consists of 17 printed pages. Examiner’s Use Paper 1 MCQ / 30 Q1 / 8 Q2 / 4 Q3 / 11 Q4 / 7 Paper 2 Section A Q5 / 10 Q6 / 20 Q7 / 20 Paper 2 Section B Q8 / 20 Total / 110 1

SECTION A (40 marks) Answer all questions in the space provided. 1(a) The graph below represents the first i onization energies from beryllium to strontium. Explain the general trend presented by the graph. [2] Energy Element Be Mg Ca Sr (b) Write the electronic configurations of chromium ion, Cr 3+. [1] 2

(c) Between Cr3+ and F -, state and explain which ion would be deflected the most when they are passed through an electric field? [2] (d) The first ionization energies of ber yllium, boron, nitrogen and oxygen are presented in the graph below. Energy Element Be B N O Explain the decrease in ionization energy from: (i) Be to B 3

(ii) N to O [3] [Total: 8] 2 Certain enthalpy changes such as ent halpy change of formation cannot be found by direct experiment. Instead it can be found by applying Hess’ Law to simple energy cycles. (a) 500 cm 3 of water was heated in a calorimeter by burning a 1.30 g of butane, C4H10. The temperature rise of the water recorded was 30 °C. Calculate the enthalpy change of combustion of butane. [2] 4

(b) The energy cycle for the complete combustion of butane is shown below. C4H10 (g) + 13/2 O2(g) 4CO2(g) + 5H2O (l) ΔHc (C4H10) 4C(s) + 5H 2(g) Using your answer in part (a) and the following enthalpy changes, calculate the entha