SAJC H2 Chem 2012 Prelim P1 QP

1 ST ANDREW’S JUNIOR COLLEGE JC2 Preliminary Examinations Chemistry Higher 2 9647/01 Paper 1 Multiple Choice 19 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. 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 22 printed pages including this page. [Turn Over

2 [Turn Over Section A For each question there are four possible answers, A , B, C and D. Choose the one you consider to be correct. 1. Group I and Group II ionic hydrides react with water. H- + H2O ® OH- + H2 In an experiment, 1 g of a sample of an ionic hydride is dissolved in excess H 2O. The resulting solution required 24.00 cm3 of a 2.0 mol dm -3 HCl solution for complete neutralisation. What is the formula of the hydride? A LiH B NaH C MgH2 D CaH2 2. Which species is oxidised and which species is reduced in the following reaction? 4TiCr2O4 + 8Rb2CO3 + 7O2 à 8Rb2CrO4 + 2Ti2O3 + 8CO2 Species oxidised Species reduced A Chromium only Carbonate ion only B Chromium only Carbonate ion and oxygen C Chromium and titanium Oxygen only D Chromium and titanium Carbonate ion and oxygen

3 [Turn Over 3. The graph below shows how pressure varies with temperature when 1 mole of helium is heated in an enclosed volume. p T/ o C0 Similar relationshi p between pressure and temperature was examined for 1 mole of gaseous XY2 which dissociates according to the following equation. XY2 (g) X (g) + Y2 (g) ∆H > 0 Which graph best represents how pressure varies with temperature of the gas? A p T/ o C0 C p 0 T / oC B p 0 T / oC D p 0 T / oC

4 [Turn Over 4. Which of the following particles has a half-filled p subshell after losing two electrons? A Ga- B As2+ C Se- D Te+ 5. Which of the following isomers is likely to have the highest boiling point? A O B O C OH D OH 6. In which of the following reactions is the H –N–H bond angle in ammonia smaller than that in the product? A 2NH3 (l) + 2Na (s) ® 2NaNH2 (s) + H2 (g) B NH3 (g) + HCl (g) ® NH4Cl (s) C 2NH3 (g) ® H2N–NH2 (l) + H2 (g) D 2NH3 (g) + O2 (g) ® 2NH2OH (l)

5 [Turn Over 7. When water vaporises, 51.6 kJ mol -1 of heat enthalpy is required. What is the entropy change when 54 g of water boils at 1 atm? A + 138 J K-1 B + 415 J K-1 C + 516 J K-1 D + 1548 J K-1 8. Ellingham diagrams are plots of ∆G against temperature, T. An Ellingham diagram for two reactions involving the oxidation of S and SO2 is as shown below: Given that, ∆G = ∆H - T∆S, which of the following correctly shows the two reactions corresponding to reactions I and II in the above Ellingham diagram? I II A 2S + 3O2 à 2SO3 2SO2 + O2 à 2SO3 B 2SO2 + O2 à 2SO3 S + O2 à SO2 C S + O2 à SO2 2S + 3O2 à 2SO3 D 2SO2 + O2 à 2SO3 2S + 3O2 à 2SO3

6 [Turn Over 9. In the conversion of compound X into com pound Z, it was found that the reaction proceeded according to the rate equation below: Rate = k [X] The intermediate Y can be isolated. Which reaction profile fits these data? A C B D energy progress of reaction X Y Z energy progress of reaction X Y Z energy progress of reaction X Y Z energy progress of reaction X Y Z

7 [Turn Over 10. A solution of vanadium (V) ions in 1 mol dm -3 H2SO4 slowly oxidises arsenic ( III) oxide to arsenic (V) oxide, according to the following equation. As2O3 + 4 VO2+ + 4 H+ à As2O5 + 4 VO2+ + 2 H2O To find the rate equation for the above reaction, two expe riments were carried out, starting with different concentrations of arsenic (III ) oxide and the concentration of VO2+ was monitored. The rate equation is most likely to be A rate = k [As2O3][VO2+] B rate = k [As2O3][VO2+]2 C rate = k [As2O3]2[VO2+] D rate = k [As2O3]

8 [Turn Over 11. The graphs below show the variation of the percentage of gaseous products present at equlibrium, with pressure and two temperatures, T oC and (T + z) oC. Which one of the following systems could the graphs represent? A N2(g) + 3H2(g) 2NH3(g) DH = - 92 kJ mol-1 B 3O2(g) + 4NH3(g) 2N2(g) + 6H2O(g) DH = - 1248 kJ mol-1 C 2N2(g) + O2(g) 2N2O (g) DH = + 82 kJ mol-1 D CO2(g) + C(s) 2CO (g) DH = + 173 kJ mol-1 12. Solutions E, F, G and H contain a strong monobasic acid, a weak monobasic acid HX, a strong base and a salt of HX , but not necessarily in the same order. The concentration and pH for each solution are shown below. Solution Concentration /mol dm-3 pH E 1.0 4.0 F 1.0 9.4 G 0.01 12.0 H 0.01 2.0 Which one of the following statements is false? A E contains a weak acid while H contains a strong acid. B Mixing 10 cm3 of E and 50 cm3 of G produces a buffer solution. C Mixing 10 cm3 of E and 50 cm3 of H produces a buffer solution. D Mixing 10 cm3 of F and 1 dm3 of H produces an acidic solution. Pressure % products at equilibrium (T + z) oC T oC

9 [Turn Over 13. At a temperature T K, 0.60 mol dm-3 of CO and 0.30 mol dm-3 of O2 were introduced into a 5 dm3 vessel and allowed to reach equilibrium. 2 CO (g) + O2 (g) 2CO2 (g) ∆H < 0 The graph below shows the changes in the concentration of CO and CO 2 in the system with time. A change was made to the system at time, t1 and t2. What were the changes made at time, t1 and t2? t1 t2 A A catalyst was added Volume of the system is increased B The temperature was increased Volume of the system is decreased C More CO2 was added An inert gas was added at constant volume D The temperature was decreased More O2 was added

10 [Turn Over 14. Use of the data booklet is relevant to this question. Two cells are connected in series as shown in the diagram where P, Q, R and S are electrodes. Which of the following correctly shows the products formed at each electrode? Cu Pt HCl(aq) Fe2(SO4)3 (aq) P Q R S P Q R S A Cu2+ H2 O2 Fe2+ B O2 Cu SO2 H2 C Cl2 H2 O2 Fe D Cu2+ Cu SO2 Fe2+ 15. Use of the data booklet is relevant to this question. Ladles are often made from sterling silver. Which aqueous solution should not be stirred with a silver ladle because a reaction could occur? A KCl B (NH4)2S4O6 C Na2SO4 D PbBr4