HCI H2 Chem 2012 Prelim P1 QP

This document consists of 19 printed pages. HWA CHONG INSTITUTION JC2 Preliminary Examinations Higher 2 CANDIDATE NAME CT GROUP 11S CENTRE NUMBER INDEX NUMBER CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet Data Booklet 9647/01 21 September 2012 1 hour READ THESE INSTRUCTIONS FIRST Write in soft pencil. Complete the information on the optical mark sheet (OMS) as shown below. There are forty questions on this paper. Answer all questions. For each question , there are four possible answers A, B, C and D. Choose the one you consider correct and record your choice in soft pencil on the OMS. 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. Write your name Write and shade your NRIC or FIN number Write your CT group

2 © Hwa Chong Institution 2012 9647 / 01 / JC2 Prelim 2012 Section A For each question there are four possible answers, A, B, C and D. Choose the one you consider to be correct. 1 When iron is reacted with aqueous iron(III) ions, iron(II) ions are formed. Assuming the reaction goes to completion, how many moles of Fe and of Fe3+(aq) would result in a mixture containing twice the number of moles of Fe 2+(aq) compared to Fe 3+(aq) once the reaction had taken place? moles of Fe moles of Fe3+(aq) A 2 4 B 2 5 C 2 6 D 2 7 2 45 cm3 of 0.8 mol dm−3 of potassium iodide and 30 cm3 of 0.5 mol dm−3 of lead(II) nitrate were mixed together. The equation for the reaction that occurs is as shown. 2KI(aq) + Pb(NO3)2(aq) → PbI2(s) + 2KNO3(aq) What will be the approximate concentration of the iodide io ns in the solution after the reaction has completed? A 0.006 mol dm−3 C 0.133 mol dm−3 B 0.080 mol dm−3 D 0.280 mol dm−3 3 Alpharadin®, containing the radioactive isotope Ra223 88 , is currently under clinical evaluation for the treatment of cancer. Ra223 88 decays to give only an element X and a high energy α-particle ( He4 2 ); the latter targets the cancer cells. Ra223 88  X + He4 2 Which row in the table correctly defines the chemical symbol for element X and the number of neutrons in its nucleus? chemical symbol for element X number of neutrons A Po 135 B Po 219 C Rn 133 D Rn 219

3 © Hwa Chong Institution 2012 9647 / 01 / JC2 Prelim 2012 4 The cylinder in a car engine has a volume of 0.500 dm 3 when the piston is at the bottom of its stroke. At this point the pressure is reduced to 95.0 kPa and the reduced pressure causes the fuel/air mixture to move into the cylinder. At the top of its stroke, the piston has compressed the gases to 25 cm3. Assuming that the temperature in the cylinder remains constant, what is the pressure of the gases (in kPa) when the piston is at the top of its stroke? A 1.90 B 4.75 C 132 D 1900 5 The dye alizarin only sticks fast to cotton when a ‘mordant’ is used. If an aluminium compound is used as a mordant under alkaline conditions, aluminium ions become bonded to the hydroxyl groups of cotton. Alizarin can bond with the aluminium ions, giving the structure below which dyes the cotton red. OO O OH Al3+ O OHH Which statement is incorrect? A All the carbon atoms in alizarin are sp2 hybridised. B The four oxygen atoms form coordinate bonds with the aluminium ion. C In the absence of a mordant, alizarin can bind to cotton via hydrogen bonding. D There is a decrease in the bond angles about the oxygen atoms of the cotton hydroxyl groups upon binding to aluminium ions. 6 The standard enthalpy change and standard entropy change of vaporisation of a compound are +23.35 kJ mol−1 and +97.41 J K−1 mol−1 respectively. What is the boiling point of the compound? A −272.8 C B −33.3 C C 0.240 C D 239.7 C alizarin ion

4 © Hwa Chong Institution 2012 9647 / 01 / JC2 Prelim 2012 7 The conversion of carbon d ioxide and water to glucose and oxygen is not energetically feasible. 6CO2(g) + 6H2O(l)  C6H12O6(aq) + 6O2(g) G = +2867 kJ mol−1 In plants, this reaction may be coupled to the hydrolysis of adenosine triphosphate (ATP) to adenosine diphosphate (ADP) and the oxidation of the NADPH cofactor to NADP +. The overall reaction may be represented by: 6CO2(g) + 18ATP(aq) + 12NADPH(aq) + 12H+(aq) + 12H2O(l) C6H12O6(aq) + 18ADP(aq) + 12NADP+(aq) + 18Pi (aq) (where Pi = inorganic phosphate group) Given the G values for the following reactions: ATP(aq) + H2O(l)  ADP(aq) + Pi(aq) G = −30.5 kJ mol−1 NADP+(aq) + H2O(l)  NADPH(aq) + H+(aq) + ½O2(g) G = +220 kJ mol−1 What is Grxn? A −6056 kJ mol−1 C +2617 kJ mol−1 B −322 kJ mol−1 D +4958 kJ mol−1 8 The rate information below was obtained for the reaction P + Q  products. [P] / mol dm−3 [Q] / mol dm−3 Rate / mol dm−3 s−1 0.01 0.05 1.9 × 10−4 0.02 0.05 3.9 × 10−4 0.02 0.01 4.0 × 10−4 If the rate constant doubles for each 10 C rise in temperature, which set of conditions will give the greatest rate of reaction? [P] / mol dm−3 [Q] / mol dm−3 Temperature / C A 0.1 0.2 40 B 0.2 0.2 30 C 0.3 0.1 30 D 0.4 0.4 20 Grxn

5 © Hwa Chong Institution 2012 9647 / 01 / JC2 Prelim 2012 9 In a microbial electrolytic cell, CO2 and H2O, are converted by electrochemically active bacteria into CH4 and O2. The electrode reactions are: Anode: 2H2O(l)  O2(g) + 4H+(aq) + 4e Cathode: CO2(g) + 8H+(aq) + 8e  CH4(g) + 2H2O(l) If the process is 80% efficient, how many hours are needed to produce 1 dm 3 of methane gas (at r.t.p.) when a current of 0.50 A is passed through the cell? A 3600248050.0 896500100   C 89650080 36002410050.0   B 36002410050.0 89650080   D 896500100 3600248050.0   10 The current dominant method for the industrial production of hydrogen is by steam reforming of methane from nat ural gas. Two reactions are involved, both being in equilibrium in closed systems: Reaction 1 CH4(g) + H2O(g)  CO(g) + 3H2(g) H = +210 kJ mol−1 Reaction 2 CO(g) + H2O(g)  CO2(g) + H2(g) H = −42 kJ mol−1 Which statement about Reactions 1 and 2 is correct? A Increasing the pressure increases the equilibrium constant for Reaction 2. B Increasing the temperature increases the equilibrium constant for Reaction 1. C Addition of a catalyst increases both the yield and rate of pr oduction of hydrogen gas. D Increasing the temperature decreases the rate constant for the forward reaction in Reaction 2. 11 What is the pH of the resultant solution when 100 cm 3 of 0.10 mol dm−3 of aqueous NH 3 and 80 cm3 of 0.15 mol dm−3 aqueous NH4Cl are mixed at 25 oC? (pKb of NH3 = 4.75) A 9.07 B 9.17 C 9.32 D 9.35 12 The numerical value of the solubility product, Ksp, of silver chromate( VI), Ag2CrO4, is 2.5 × 10−22 at 25 oC. Which statement about silver chromate(VI) is correct? A The units of Ksp of silver chromate(VI) are mol2 dm−6. B The solubility of silver chromate(VI) is 3.97 × 10−8 mol dm−3. C Addition of hydrochloric acid will decrease the solubility of silver chromate(VI). D Addition of hydrochloric acid will decrease the numerical value of Ksp of silver chromate(VI).

6 © Hwa Chong Institution 2012 9647 / 01 / JC2 Prelim 2012 13 The graph below shows the variation in the melting points for eight consecutive elements in the Periodic Table, all with atomic number be