AJC H1 CHEM P2

ANDERSO N JUNIOR COLLEGE 2009 PRELIMINARY EXAMINATION HIGHER 1 _______________________________________________________________________ C H E M I S T R Y 8872/02 Paper 2 18 September 2009 2 hours Candidates answer Section A on the Question Paper. Additional Materials : Writing Paper Data Booklet _______________________________________________________________________ READ THESE INSTRUCTIONS FIRST Write your name and PDG on all the work you hand in. Write in dark blue or black pen on both sides of the paper. You may use a soft pencil for any diagrams, graphs or rough working. Do not use staples, paper clips, highlighters, glue or correction fluid. Section A Answer all questions. Section B Answer any two questions on separate answer paper. A Data Booklet is provided. The number of marks is given in brackets [ ] at the end of each question or part question. At the end of the examination, attach your answer for Section B to this question paper. For Examiner’s Use Q1 Q2 Q3 Section A Q4 Section B Total 80 Name: ……………………………………( ) PDG: ……………………………………. _______________________________________________________________________ This paper consists of 14 printed pages including this cover page. Anderson Junior College H1 Chemistry Preliminary Examination 2009 1

Anderson Junior College H1 Chemistry Preliminary Examination 2009 2 Section A Answer all questions in this section in the spaces provided. 1 (a) What is meant by the term empirical formula? ………..……….…………………………………………………………………………………………… ……….……………………………………………………..……………………………………………[1] (b) A gaseous hydrocarbon, A, has a composition by mass: C, 85.7 %; H, 14.3 %. (i) Calculate the empirical formula of the hydrocarbon, A. Empirical Formula of compound A : …………………………………………………………………… (ii) When 10 cm 3 of A underwent complete combustion in excess oxygen, the remaining gases occupied 100 cm 3 at 120 oC and 1 atm. When the gases were cooled to room temperature and pressure, the volume of gases was reduced to 60 cm3. Determine the molecular formula of A. [3]

(c) Draw the structural formulae of all the isomers of compound A and state the type(s) of isomerism displayed. [4] [Total: 8] 2 (a) The kinetics of the acid–catalysed reaction of propanone with iodine C H 3COCH3(aq) + I2(aq) CH2ICOCH3(aq) + HI(aq) can be investigated e xperimentally by varying the concentrations of the three substances involved. The following results were obtained in an experiment. [H +] = 0.10 mol dm–3 [CH3COCH3] = 0.10 mol dm–3 [I2] / mol dm–3 [H+] = 0.20 mol dm–3 time / min 3 Anderson Junior College H1 Chemistr y Preliminary Examination 2009

(i) Deduce the order of reaction with respect to  iodine Order of reaction with respect to iodine: ………………………………………………  hydrogen ions Order of reaction with respect to hydrogen ions: ……………………………………..  propanone Order of reaction with respect to propanone: ………………………………………..... [H +] = 0.10 mol dm–3 [CH3COCH3] = 0.15 mol dm–3 [CH3COCH3] = 0.10 mol dm–3 [I2] / mol dm–3 time / min Anderson Junior College H1 Chemistry Preliminary Examination 2009 4

Anderson Junior College H1 Chemistry Preliminary Examination 2009 5 (ii) Hence, write a rate equation for the reaction and determine a value for the rate constant k, including its units. (iii) Hydrogen ions are found to catalyse the above reaction. Explain, with the aid of the Maxwell Boltzmann distribution curve, how the use of hydrogen ions can help to speed up the rate of reaction. …………………………………………………………………………………………………….. ..…………………………………………………………………………………………………… ..……………………………………………………………………………… …………………[9] (b) Many che mical compounds exist as crystalline solid structures.

Anderson Junior College H1 Chemistry Preliminary Examination 2009 6 Describe, with the aid of a diagram, the structure of crystalline solid iodine. …………………………………………..…………………………………………………………………. …………………………………………………………………………………………………………...[2] (c) Propanal, CH 3CH2CHO, and propanone are isomers which can be distinguished by using aqueous iodine. State the condition needed for this test and the observation made when the test is performed on propanal and propanone. Conditions: ………………………………………………………………………………………….. Observations: ……………………………………………………………………………………….[2] [Total: 13] 3 (a) Describe the variations in melting points of magnesium, silicon and sulfur. Explain these variations in terms of their structures and bonding. ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… …………………………………………………………………………………………………………...[3] (b) In an experiment to determine the enthalpy change of reaction between magnesium and

hydrochloric acid, the following procedure was followed.  The temperature of 40 cm3 of 1 mol dm-3 hydrochloric acid was recorded for 2.5 minutes.  0.25 g of magnesium powder was added to the acid at 3 minutes.  The temperature of the mixture was recorded at regular intervals from 3.5 minutes. The following results were obtained. (i) From the graph obtained, determine the maximum temperature reached. Maximum temperature reached = …………………………………………………………….. (ii) Write an equation for the reaction between magnesium and hydrochloric acid. …………………………………………………………………………………………………….. (iii) Calculate the enthalpy change of the reaction. [You may assume the specific heat capacity of the mixture to be 4.2 J g -1 K-1.] (iv) By using the answer obtained in (b)(iii) and given the following energy cycle and Anderson Junior College H1 Chemistry Preliminary Examination 2009 7

Anderson Junior College H1 Chemistry Preliminary Examination 2009 8 ……… ………………………………………………………………………………….. [7] [Total: 10] 4. res of automobiles, is made from 1,3- utadiene. The structure of 1,3-butadiene is shown below: thermochemical data, determine the standard enthalpy change of reaction between magnesium oxide and hydrochloric acid, H 1. H f (MgO) = - 600 kJ mol-1 H f (H2O) = - 286 kJ mol-1 Mg (s) + ½ O 2 (g) + 2HCl (aq) MgCl2 (aq) + H2 (g) + ½ O2 (g) H 1 MgO (s) + 2HCl (aq) MgCl2 (aq) + H2O (l) H 1 = … Synthetic rubber, which is widely used to make the ty b C H HC C C H H HH 1,3-butadiene ) hat type of hybridization is present in the 1,3-butadiene molecule? ………………………………………………………………………………………………………...[1] (b) shapes of the hybrid orbitals around one carbon atom in the 1,3-butadiene olecule. [1] (a W … Sketch the m

Anderson Junior College H1 Chemistry Preliminary Examination 2009 9 (c) and write an equation for each of the reactions, showing the tructures of the products. ) 1,3-butadiene and aqueous bromine in the dark bservation:………………………………………………………………………………………... quation:…………………………………… ………………………………………………………. i) 1,3-butadiene and cold aqueous potassium manganate(VII) bservation:………………………………………………………