Chemistry 12 JANUARY Course Code = CH. Student Instructions

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1 MINISTRY USE ONLY MINISTRY USE ONLY Place Personal Education Number (PEN) here. Place Personal Education Number (PEN) here. MINISTRY USE ONLY Chemistry Ministry of Education JANUARY 2002 Course Code = CH Student Instructions 1. Place the stickers with your Personal Education Number (PEN) in the allotted spaces above. Under no circumstance is your name or identification, other than your Personal Education Number, to appear on this booklet. 2. Ensure that in addition to this examination booklet, you have a Data Booklet and an Examination Response Form. Follow the directions on the front of the Response Form. 3. Disqualification from the examination will result if you bring books, paper, notes or unauthorized electronic devices into the examination room. 4. When instructed to open this booklet, check the numbering of the pages to ensure that they are numbered in sequence from page one to the last page, which is identified by END OF EXAMINATION. 5. At the end of the examination, place your Response Form inside the front cover of this booklet and return the booklet and your Response Form to the supervisor.

2 PART A: MULTIPLE CHOICE Value: 60 marks INSTRUCTIONS: Suggested Time: 70 minutes For each question, select the best answer and record your choice on the Response Form provided. Using an HB pencil, completely fill in the circle that has the letter corresponding to your answer. Selected multiple-choice questions are worth 2 marks. 1. Which of the following has the greatest reaction rate? (1 mark) A. C( s) + O2( g) CO2( g) B. 2HO 2 2( l) 2HO 2 ( l) + O2( g) C. 2Al( s) + 3CuCl2( aq) 2AlCl3 ( aq) + 3Cu( s) D. NaCl + AgNO AgCl + NaNO ( aq) 3( aq) ( s) 3( aq) 2. Which factor explains why potassium generally reacts faster than sodium? (1 mark) A. surface area B. temperature C. concentration D. nature of reactants 3. What happens to the PE and KE of the reactant particles as the activated complex is formed? (1 mark) PE KE A. increases decreases B. increases increases C. decreases decreases D. decreases increases OVER

3 4. Consider the following PE diagram: (2 marks) 200 PE (kj) Progress of the reaction What are the values of H and activation energy ( E a ) for the forward reaction? H (kj) E a (kj) A B C D Consider the following reaction mechanism: (1 mark) Step 1 Cl2 2Cl Step 2 CHCl3 + Cl HCl + CCl3 Step 3 CCl3 + Cl CCl4 Which of the following is a reactant in the overall reaction? A. Cl B. HCl C. CCl 3 D. CHCl 3-2 -

4 6. Consider the following PE diagram for a catalyzed and uncatalyzed reaction: (2 marks) PE (kj) Progress of the reaction Which of the following describes the reverse reaction? Reverse Reaction Activation Energy (kj) H (kj) A. catalyzed B. uncatalyzed C. catalyzed D. uncatalyzed Consider the following: (1 mark) 2SO2( g) + O 2( g) 2SO3 ( g) Initially, SO 3 is added to an empty flask. How do the rate of the forward reaction and SO 3 [ ] change as the system proceeds to equilibrium? Forward Rate [ SO 3 ] A. decreases increases B. decreases decreases C. increases increases D. increases decreases OVER

5 8. Consider the following reaction: (2 marks) N2( g) + 3H2( g) 2NH3 ( g) + energy What positions do minimum enthalpy and maximum entropy tend toward? Minimum Enthalpy Maximum Entropy A. reactants products B. reactants reactants C. products products D. products reactants Use the following equilibrium equation to answer questions 9 and 10. CO2( g) + H2( g) H2O( g) + CO( g) 9. Which two stresses will each cause the equilibrium to shift to the left? (1 mark) A. increase H 2 B. decrease H 2 C. increase CO 2 D. decrease CO 2 [ ], increase [ CO] [ ], increase [ H 2 O] [ ], decrease [ CO] [ ], decrease [ H 2 O] 10. Which of the following graphs represents the forward rate of reaction when H 2 O( g) is added to the above equilibrium at time = t 1? (1 mark) A. B. rate rate t 1 time t 1 time C. D. rate rate t 1 time t 1 time - 4 -

6 11. Consider the following: (1 mark) 2NH3 ( g) N2( g) + 3H2( g) Initially, some NH 3 is placed into a 1. 0 L container. At equilibrium there is mol N 2 present. What is the H 2 A mol L B mol L C mol L D mol L [ ] at this equilibrium? 12. Which reaction has the following equilibrium expression? (1 mark) [ NO ] 4 [ H O ] K eq = NH O [ 3] [ 2] 6 A. 4NH3 ( g) + 7 O 2( g) 4NO2 ( g) + 6HO 2 ( g) B. 4NH3 ( aq) + 7 O 2( g) 4NO2 ( aq) + 6HO 2 l C. 4NO2 ( aq) + 6HO 2 ( l) 4NH3 ( g) + 7 O 2( g) D. 4NO2 ( g) + 6HO 2 ( g) 4NH3 ( g) + 7 O 2( g) ( ) 13. What will cause the K eq for an exothermic reaction to increase? (1 mark) [ ] [ ] A. increasing reactants B. decreasing products C. increasing the temperature D. decreasing the temperature OVER

7 14. Consider the following equilibrium: (1 mark) PCl 5( g) PCl3 ( g) + Cl2( g) Keq = In a 1. 0 L container an equilibrium mixture contains mol PCl5 and mol PCl 3. How many moles of Cl 2 are also present at equilibrium? A B C D mol mol mol mol The equation that describes the solubility equilibrium of Ca3( PO4) 2 is (1 mark) ( ) 6+ 3 s aq + 4 ( aq) ( ) 2+ 3 s aq + 4 ( aq) ( ) 3+ 2 s aq + 4 ( aq) ( ) ( 2+ 3 ) + ( 4 ) 2 aq A. Ca3 PO4 2( ) Ca3 ( ) 2PO B. Ca3 PO4 2( ) 3Ca ( ) 2PO C. Ca3 PO4 2( ) 2Ca ( ) 3PO D. Ca3 PO4 2( s) Ca PO 3( aq) ( ) 16. In a saturated solution of Ag2C2O4, the [ Ag + ]= M. What is the solubility of Ag2C2O4 in this solution? (1 mark) A M B M C M D M - 6 -

8 17. When equal volumes of 0. 2 M solutions are mixed, which of the following combinations forms a precipitate? (1 mark) A. CaS and Sr( OH) 2 B. H2SO4 and MgCl2 ( ) C. NH4 2SO4 and K2CO3 D. H2SO3 and NaCH3COO A solution contains 0. 2 M Zn + and 0. 2 M Sr +. An equal volume of a second solution was added, forming a precipitate with Sr 2+ but not with Zn 2+. What is present in the second solution? 2 (1 mark) A 0. 2M Cl B M OH 2 C M SO 4 3 D M PO The K sp expression for a saturated solution of Ba3( AsO4) 2 is (1 mark) sp = 2+ 3 [ ][ 4 ] sp = [ ] [ 4 ] sp = 2+ 3 [ 3 ][ 2 4 ] sp = 2+ 3 [ 3 ] [ 2 4 ] A. K Ba AsO B. K Ba AsO C. K Ba AsO D. K Ba AsO The solubility of NiCO 3 is g L. Determine the K sp value of NiCO 3. (2 marks) A B C D OVER

9 21. Calculate the solubility of PbSO 4. (1 mark) A B C D M M M M 22. When a solution containing Ag + is mixed with a solution containing BrO 3, the trial ion product is determined to be What would be observed? (2 marks) A. A precipitate would form since trial ion product < Ksp B. A precipitate would form since trial ion product > Ksp. C. A precipitate would not form since trial ion product < Ksp D. A precipitate would not form since trial ion product > Ksp 23. Which of the following represents the complete neutralization of H3PO4 by NaOH? (1 mark) A. H3PO4 + NaOH NaH2PO4 + H2O B. H3PO4 + 3NaOH Na3PO4 + 3H2O C. H3PO4 + 2NaOH Na2HPO4 + 2H2O D. H3PO4 + NaOH NaH + HPO4 + H2O 24. The conjugate base of HBO 3 2 is (1 mark) A. BO 3 2 B. BO 3 3 C. HBO 3 D. H2BO3-8 -

10 25. When comparing equal volumes of M HNO 3 with M HNO 2, what would be observed? (1 mark) A. The ph values would be the same. B. The electrical conductivities would be different. C. The effects on blue litmus paper would be different. D. The volumes of M NaOH needed for neutralization would be different. 26. Consider the equilibrium: (2 marks) 2 aq aq aq 2 4 aq HF( ) + HPO 4 ( ) F ( ) + H PO For the above equilibrium, identify the weaker acid and determine whether reactants or products are favoured. ( ) Weaker Acid Side Favoured A. HF products B. HF reactants C. H2PO4 D. H2PO4 products reactants 27. The ionization of water can be represented by (1 mark) A. 2HO 2 ( l) 2H2( g) + O2( g) 2 B. HO 2 ( l) 2H ( aq) + O ( aq) C. HO 2 ( l) HO 3 ( aq) + OH( aq) D. 2HO 2 ( l) HO 3 ( aq) + OH ( aq) Calculate the poh of a M HBr solution. (1 mark) A B C D OVER

11 29. Calculate the value of K b for HPO 4 2. (1 mark) A B C D Which of the following is the net ionic equation describing the hydrolysis of KCN ( aq)? (1 mark) + A. K ( aq) + H O 2 ( l) KOH( aq) + H ( aq) + ( aq) 2 ( l) ( aq) aq B. KCN + H O K + CN ( ) C. CN ( aq) + H O 2 ( l) HCN( aq) + OH ( aq) + aq aq aq D. CN ( ) + H O 2 ( l) 2H ( ) + CNO ( ) Which of the following 1. 0 M salt solutions will be acidic? (2 marks) A. NaNO 3 B. NaHCO 3 C. NaHSO 4 D. NaHPO The ph at which an indicator changes colour is known as its (1 mark) A. standard point. B. transition point. C. equivalence point. D. stoichiometric point

12 33. An indicator is blue at a ph of and colourless at a ph of Identify the indicator and determine its K a value. (2 marks) Indicator K a A. thymolphthalein B. thymolphthalein C. bromthymol blue D. bromthymol blue A ml sample of H2SO3 is completely neutralized by titration with ml of M NaOH. Calculate the concentration of the acid. (2 marks) A M B M C M D M 35. A common source of NO 2 is (1 mark) A. a fuel cell. B. a lead smelter. C. an aluminum smelter. D. an automobile engine. 36. The ph at the stoichiometric point for the complete neutralization of a strong acid by a weak base will be (1 mark) A. equal to 7. 0 B. equal to 7. 2 C. less than 7. 0 D. greater than OVER

13 37. A buffer solution can be prepared by dissolving equal moles of (1 mark) A. a weak base and a strong base. B. a weak acid and its conjugate base. C. a strong base and its conjugate acid. D. a strong acid and its conjugate base. 38. A reducing agent (2 marks) A. loses electrons and is reduced. B. gains electrons and is reduced. C. loses electrons and is oxidized. D. gains electrons and is oxidized. 39. Which of the following could be produced by the reduction of NO 2? (1 mark) A. NO B. N 2 O 4 C. N 2 O 5 D. HNO Consider the following redox equation: (1 mark) NO + SO + Fe + 2H O FeS + 3NO + 4H Which of the following is being oxidized? A. NO B. Fe 3+ C. H 2 O D. 2 SO

14 41. What is the oxidation number of Cr in Cr O 2 7 2? (1 mark) A. +6 B. +7 C. +12 D Which of the following represents a spontaneous redox reaction? (1 mark) 2+ A. 2Br + Hg Br + Hg B. Cu + Sn Cu + Sn C. HCl + NaOH NaCl + H2O D. AuCl4 + 3Ag Au + 4Cl + 3Ag Which of the following is the balanced half-reaction for (1 mark) N O NH OH (acidic) A. N O + 4H + 3e NH OH B. N O H H O NH OH e C. N O H H O NH OH e D. N O H H O e NH OH OVER

15 Use the following diagram to answer questions 44 to 46. Volts cathode 1.0 M KNO3 Cu (anode) 1.0 M solution 1.0 M Cu(NO 3 ) Which material could be used as the cathode to produce an E =+046. V? (1 mark) A. Pb B. Co C. Ag D. MnO 2 cell 45. In what directions do the electrons and cations move? (2 marks) Direction of Electrons Direction of Cations A. toward the cathode toward the anode B. toward the cathode toward the cathode C. toward the anode toward the anode D. toward the anode toward the cathode 46. The concentration of Cu 2+ in the copper half-cell will (2 marks) A. increase as Cu loses electrons and is reduced. B. increase as Cu loses electrons and is oxidized. C. decrease as Cu gains electrons and is reduced. D. decrease as Cu gains electrons and is oxidized

16 47. Which of the following metals could be used to cathodically protect iron? (1 mark) A. tin B. lead C. zinc D. copper 48. Which of the following is formed at the anode during the electrolysis of 1. 0 M KF? (1 mark) A. K B. F 2 C. H 2 D. O 2 This is the end of the multiple-choice section. Answer the remaining questions directly in this examination booklet OVER

17 PART B: WRITTEN RESPONSE Value: 40 marks INSTRUCTIONS: Suggested Time: 50 minutes You will be expected to communicate your knowledge and understanding of chemical principles in a clear and logical manner. Your steps and assumptions leading to a solution must be written in the spaces below the questions. Answers must include units where appropriate and be given to the correct number of significant figures. For questions involving calculations, full marks will NOT be given for providing only an answer. 1. Consider the following reaction: (3 marks) C12H22O11( s) 11 H2O( g) + 12C( s) The rate of decomposition of C12H22O11 is 075. mol min. What mass of C is produced in seconds? 2. Define the term activation energy. (2 marks)

18 3. Consider the following equilibrium: (2 marks) ( ) ( ) 2NF2 g N2F4 g Equilibrium shifts to the right when volume is decreased. Describe the changes in reaction rates that cause this shift to the right. 4. Consider the following: (4 marks) H2( g) + I 2( g) 2HI( g) Initially, mol H 2 and mol I 2 are added to an empty L container. At equilibrium, the [ I2]= mol L. What is the value of K eq? OVER

19 5. When equal volumes of M Pb NO3 2 precipitate of PbCl 2 forms. ( ) and M KCl are mixed, a a) Write the formula equation for the above reaction. (1 mark) b) Write the complete ionic equation for the above reaction. (1 mark) c) Write the net ionic equation for the above reaction. (1 mark) 6. Calculate the maximum CO 3 2 [ ] that can exist in M Mg NO3 2 ( ). (3 marks)

20 7. The two reactants in an acid-base reaction are HNO 2( aq) and HCO 3 ( aq). a) Write the equation for the above reaction. (2 marks) b) Define the term conjugate acid-base pair. (1 mark) c) Write the formulas for a conjugate acid-base pair for the above reaction. (1 mark) OVER

21 8. At C, K = w for pure water. a) Calculate the ph of water at C. (3 marks) b) A mixture of the indicators phenolphthalein and bromcresol green is added to the water. What is the resulting colour of the mixture? Explain. (2 marks) Resulting colour: Explanation:

22 9. At a particular temperature a 1. 0 M H2S solution has a ph = Calculate the value of K a at this temperature. (4 marks) 10. What is the main function of a buffer solution? (1 mark) OVER

23 11. A titration is performed to determine the concentration of Fe 2+ in ml of an FeSO 4 solution. It requires ml of M KMnO 4 to reach the equivalence point according to the following equation: MnO + 5Fe + 8H Mn + 5Fe + 4H O Calculate the [ Fe 2+ ]. (4 marks)

24 12. Consider the following diagram: CuSO 4 K 2 SO 4 NaI + H 2 O Students are asked to produce hydrogen and oxygen gas by the electrolysis of water. They are given three substances CuSO4, K2SO4 and NaI to prepare an electrolytic solution that will only produce hydrogen and oxygen. ( ) to choose from a) Which substance should be selected? Explain why. (3 marks) Substance: Explanation: b) Write the equation for the half-reaction that occurs at the anode in the electrolytic cell. (1 mark) c) Explain why it would not be acceptable to use a copper anode in this cell. (1 mark) END OF EXAMINATION

Chemistry 12 APRIL Course Code = CH. Student Instructions

Chemistry 12 APRIL Course Code = CH. Student Instructions MINISTRY USE ONLY MINISTRY USE ONLY Place Personal Education Number (PEN) here. Place Personal Education Number (PEN) here. MINISTRY USE ONLY Chemistry 12 2002 Ministry of Education APRIL 2002 Course Code