PJC H2 Chem 2012 Prelim P1 QP

Name: Index No.: CT Group: 11 PIONEER JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATION HIGHER 2 CHEMISTRY 9647/01 Paper 1 Multiple Choice 20 September 2012 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. Write your name, Centre number and index number on the Answer Sheet in the spaces provided unless this has been done for you. 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 separate Answer Sheet. Read the instructions on the Answer Sheet very carefully. 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.

2 © PJC 2012 9647/01/JC2 PRELIM/2012 Section A For each question, there are four possible answers labelled A, B, C and D. Choose the one you consider to be correct. 1 Acidified, aqueous potassium manganate(VII) oxidises ethanedioate ions, C2O42-, to CO2. 2MnO4-(aq) + 5C2O42-(aq) + 16H+(aq) → 2Mn2+(aq) + 10CO2(g) + 8H2O(l) What is the concentration of potassium manganate( VII), in mol dm 3, if 20 cm 3 is required to completely oxidise 2.0 x 10-3 mol of the salt KHC2O4.H2C2O4? A 310 x 2.0x 20 1000 x 2 5 - B 310 x 4.0 x 20 1000 x 2 5 - C 310 x 2.0x 20 1000 x 5 2 - D 310 x 4.0 x 20 1000 x 5 2 - 2 The radioactive decay of polonium, Po210 84 , can be simply represented by the following equation. Po210 84 → Pb206 82 + α + 2e- What would be the path taken by the alpha particle, α, when it is passed through an electric field? source - + 1H+ A B C D

3 © PJC 2012 9647/01/JC2 PRELIM/2012 3 What are the values of angle x, y and z in a molecule of Disperse Yellow? C N N O CH3 NH O CH3 H x y Disperse Yellow z angle x angle y angle z A 90 115 105 B 90 180 180 C 120 115 105 D 120 180 115 4 Which of the following pairs of graphs share the same general shape according to ideal gas law for a fixed mass of gas? A p against V (at constant T) and V/T against T (at constant p) B pV against V (at constant T) and V/T against T (at constant p) C p against T (at constant V) and pV against p (at constant T) D V against T (at constant p) and pV against p (at constant T) 5 Travellers to countries with cold climate may sometimes use heat packs to keep warm. One example is the sodium ethanoate heat pack. This consists of a supersaturated solution of sodium ethanoate and a small metal disc containing very small crystals of sodium ethanoate. When the disc is broken, the small crystals of sodium ethanoate are released into the solution and act as nucleation sites to catalyse the crystallisation reaction of sodium ethanoate. Which line gives the signs of ∆H, ∆S and ∆G for the overall process? ∆H ∆S ∆G A - - - B - - + C + + - D + + +

4 © PJC 2012 9647/01/JC2 PRELIM/2012 6 Barium reacts with water to form barium hydroxide and hydrogen. Ba(s) + 2H2O(l) → Ba(OH)2(aq) + H2(g) The standard enthalpy change for this reaction can be measured in the laboratory. What further information is needed to calculate the standard enthalpy change of formation of solid barium hydroxide? I Standard enthalpy change of formation of water II Standard enthalpy change of solution of barium hydroxide III Standard enthalpy change of hydration of barium ion IV Standard enthalpy change of hydration of hydroxide ion A I only B I and II C III and IV D I, II, III and IV 7 The distribution of the number of molecules with energy E is given in the sketch for two temperatures, T 1 and a higher temperature T 2. The letters P , Q, R refer to the separate and differently shaded areas. The activation energy is marked on the energy axis. Which expression gives the fraction of the molecules present which have at least the activation energy at the higher temperature T2? A Q P B QR P + C QR PQ + + D QR PQR + ++ Number of molecules with energy E T1 T2 energy E activation energy region P region Q region R Legend

5 © PJC 2012 9647/01/JC2 PRELIM/2012 8 Aspirin is an analgesic often used to relieve minor aches and pains. The chemical stability of aspirin is of great importance since it becomes less effective when exposed to high temperature and moisture. A kinetic study on the reaction of aspirin and water was conducted. The graph below shows the concentration of aspirin against time for this reaction. What does the shape of the graph suggest about this reaction? A It is exothermic. B It is endothermic. C It shows first order kinetics. D It produces its own catalyst. O OH O CH 3 O + H2O aspirin O OH OH + CH3COOH [aspirin] time

6 © PJC 2012 9647/01/JC2 PRELIM/2012 9 Use of the Data Booklet is relevant to this question. A cell is set up by connecting a Cu 2+/Cu half-cell and an acidified Cr 2O72−/Cr3+ half- cell under standard conditions. Which of the following correctly describes the effect on the e.m.f of the cell when the corresponding change is made? Change Effect on e.m.f of cell A replace copper with an alloy of copper and silver increases B addition of concentrated H2SO4 into reduction half-cell decreases C addition of dilute NaOH into oxidation half-cell decreases D addition of water into oxidation half-cell increases 10 When a dilute sulfate solution of a metal J is electrolysed, the metal J and a diatomic gas K are produced at the cathode and the anode respectively in the molar ratio 2:1. In another experiment, the same quantity of electricity is used to electrolyse a saturated sodium chloride solution and a gas L is evolved at the anode. What is the molar ratio of J:K:L? A 2:1:1 B 2:1:2 C 4:2:1 D 4:2:3

7 © PJC 2012 9647/01/JC2 PRELIM/2012 11 The following equation represents the conversion of Y2 to Y. Y2(g) ⇌ 2Y(g) The conversion was studied using a fixed amount of Y 2 in a reaction vessel. At different times during the experiment, changes were made to the conditions in the reaction vessel. The change in the concentrations in the equilibrium mixture with time is given by the graph below: Which one of the following statements is correct? A A catalyst was added at T1. B There was a decrease in volume of the reaction vessel at T2. C There was an increase in temperature at T2. D More Y2 was introduced at T2. 12 A pure sample of dinitrogen tetraoxide at an initial pressure of 1 atm is allowed to reach equilibrium in a vessel of constant volume and constant temperature. N2O4 2NO2 What is the equilibrium constant, K p, for this reaction, given that the equilibrium pressure is 1.5 times greater than the initial pressure? A 1 atm B 2 atm C 3 atm D 4 atm

8 © PJC 2012 9647/01/JC2 PRELIM/2012 13 The table below shows the values of the ionic product of water, Kw, at two different temperatures. Temperature / oC Kw / mol2 dm-6 25 62 1.00 ´ 10-14 1.00 ´ 10-13 Which of the following statements is correct for pure water? A The ionic dissociation of water is an exothermic process. B At 62 oC, pH = 14 − pOH. C At 62 oC, pH < pOH. D At 62 oC, it is neutral and pH < 7. 14 A sample of waste solution at pH 1 is found to contain 0.100 mol dm -3 zinc sulfate and 0.100 mol dm-3 lead(II) sulfate. Solid sodium hydroxide is slowly added until the pH is 5. The solubility product of zinc hydroxide is 3.00 x 10 -17 mol3 dm-9 and that of lead( II) hydroxide is 1.42 x 10-20 mol3 dm-9. Which statement describes what happens in the solution? A No precipitate is