SAJC H2 CHEM P1 Prelim

1 [Turn Over ST ANDREW’S JUNIOR COLLEGE JC2 Preliminary Examinations Chemistry Higher 2 9647/01 Paper 1 Multiple Choice 22 September 2011 1 hour Additional Materials: Multiple Choice Answer Sheet, Data Booklet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. There are 40 questions on this paper. Answer all questions. For each question there are four possible answers A, B, C and D. Chose the one you consider correct and record your choice in soft pencil on the separate Answer Sheet. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in this booklet. This document consists of 19 printed pages including this page.

2 [Turn Over Section A For each questions, there are four possible answers, A, B, C and D. Choose the one you consider to be correct. 1 A bottle of unknown hydrocarbon was found in a laboratory and had the following information on its label: Boiling point / C 63.0 Melting point/ C -139.8 Density / g cm-3 0.673 When 25 cm3 of this hydrocarbon was burned in excess oxygen, 28.8 dm 3 of gas was formed at room temperature and pressure. Which of the following could be the empirical formula for this hydrocarbon? A CH2 B CH3 C C5H12 D C6H12 2 Sulfur compounds exist in multiple oxidation states. Which of the following options arranges compounds in increasing oxidation state of sulfur? A SO4 2- , SO2, S, H2S B S, H2S, SO2, SO4 2- C S, SO2, H2S, SO4 2- D H2S, S, SO2, SO4 2- 3 Which of the following is an isotope of oxygen? A B C 2 D 2

3 [Turn Over 4 In an experiment, the length of a hydrogen bond formed between HF molecules was measured to be 155 pm while that formed between H2O molecules was 197 pm. (1 pm = 10-12 m) Which is not a possible explanation for the above observations? A Oxygen is bigger than fluorine B Fluorine is more electronegative than oxygen. C The hydrogen bond between HF molecules is weaker than between H2O molecules. D The lone pair involv ed in hydrogen bonding in HF is in a smaller orbital compared to the lone pair involved in H2O. 5 Which of the following compounds is planar? A C6H5CH3 B [CuCl4]2- C C6H14 D O3 6 Sodium ethanoate is used in food additives as it is safe to consume. Which of the following is most likely to be true for sodium ethanoate? A It is more soluble in water than sodium chloride. B It has a lower melting point than sodium chloride. C A solution of sodium ethanoate is more acidic than a solution of sodium chloride. D A solution of sodium ethanoate has a higher electrical conductivity than a solution of sodium chloride.

4 [Turn Over 7 Which graph best represents the behaviour of an ideal gas at constant temperature, where the ratio of the number of moles of gas in containers X and Y are 3:1 respectively? (ρ refers to the density of the gas) A C B D V X Y P ρ X Y V X Y P V Y X

5 [Turn Over 8 A student carried out an experiment to determine the enthalpy change of combustion of octane. The following data was collected. Mass of water used / g 50.00 Initial temperature of water, Ti / oC 28.0 Max temperature of water, Tf / oC 34.0 Mass of spirit lamp and octane before combustion, minitial / g 44.52 Mass of spirit lamp and octane after combustion, mfinal / g 44.00 Which of the following expression shows the calculation of the magnitude of the enthalpy change of combustion of octane? A 114/40 )2834(x18.4x)00.4452.44(  combustionH B 50 )2834(x18.4x52.44  combustionH C 114/)00.4452.44( )301307(x18.4x50   combustionH D )00.4452.44( )2834(x18.4x50   combustionH 9 Which of the following statements is incorrect? A The slow step for the reaction mechanism between bromoethane and aqueous sodium hydroxide involved the formation of an intermediate compound. B The reaction between propanone and iodine can take place without the use of acid as catalyst. C The reaction between ethene and hydrogen gas has relatively high activation energy. D Dimerisation of NO 2 molecules into N 2O4 is a fast reaction with low activation energy.

6 [Turn Over 10 Consider the following reaction between nitrogen dioxide and carbon monoxide: NO2(g) + CO(g) → NO(g) + CO2(g) This reaction is carried out accordingly to the proposed mechanism: Step 1 2NO2 (g) N2 (g) + 2O2 (g) [slow] Step 2 X (g) + Y (g) Z (g) [fast] Step 3 N2 (g) + O2 (g) 2NO (g) [fast] Which of the following are possible identities of X, Y and Z? X Y Z A 2CO 2NO O2 B 2CO NO O2 C 2CO O2 2CO2 D 2CO 2O2 CO2 11 Use of the Data Booklet is relevant to this question. An antique pendant is to be chrome -plated. The pendant is dipped into a basic chromate ( VI) solution where it serves as an electrode in an electrolytic cell. Oxygen is formed on the other electrode. Which one of the following statements is correct? A Oxidation of water occurs to form oxygen. B The pendant is the anode of the electrolytic cell. C It takes about 16 hours to plate 52 g of chromium, if the current used is 1A. D For every 104 g of chromium plated, 3 moles of oxygen gas is evolved.

7 [Turn Over 12 Scientists are discovering that microbial fuel cell (MFC) technology is a viable alternative to power generation in remote locations. Powered only by water based organic waste such as methanol and the natural electrical generation processes by the bacteria, usable power for man can be harnessed, captured in batteries and utilized as necessary. An example of a MFC is as shown below. Which of the following statements about the above MFC is incorrect? A Electrons flow from the right electrode to the left electrode. B Methanol is oxidized in this reaction. C The pH decreases at the anode. D Porous electrodes are used to increase the rate of the reaction. 13 The standard redox potential for the half reaction Which cell would be used to determine this standard value? A Pt electrode in a solution containing 1 mol dm -3 Hg2+ against Pt electrode in 1 mol dm-3 Hg+. B Hg electrode in a solution containing 1 mol dm -3 Hg2+ against Hg electrode in 1 mol dm-3 Hg+. C Pt electrode in a solution containing 1 mol dm -3 Hg2+ and 1 mol dm -3 Hg+ against a standard hydrogen electrode. D Hg electrode in a solution containing 1 mol dm -3 Hg2+ and 1 mol dm-3 Hg+ against a standard hydrogen electrode.

8 [Turn Over 14 When the gases dinitrogen tetroxide and nitrogen monoxide are mixed in a 1:2 ratio, the two gases slowly react to form the blue compound dinitrogen trioxide according to the following equilibrium. N2O4 (g) + 2NO (g) 2N2O3 (g) ΔHθ = -26 kJmol-1 The forward and backward rate constants are given as k1 and k-1 respectively. What happens to the equilibrium constant Kp, k 1, and k-1 if at equilibrium, the temperature of the reaction mixture is increased? k1 k-1 Kp A increases increases increases B unchanged increases unchanged C increases increases decreases D decreases decreases decreases 15 Calculate the pH of the resulting solution when 0.1 mole of aqueous nitric acid is added to a 1 dm 3 of solution containing 1.0 mol dm -3 of propanoic acid and 1.0 mol dm -3 of sodium propanoate. (Ka propanoic acid = 1 x 10-5 mol dm-3) A 5.08 B 5.00 C 4.91 D 4.00 16 The solubility product of a substance is K. If the concentration of the cation in a saturated solution is found to be ( K ) , which of the following is most likely to be the substance? A Cr(OH)3 B Mg3(PO4)2 C Ga2(SO4)3 D PbBr2

9 [Turn Over 17 Conside