Chemistry 1 June 00 Provincial Examination ANSWER KEY / SCORING GUIDE CURRICULUM: Organizers 1. Reaction Kinetics. Dynamic Equilibrium 3. Solubility Equilibria 4. Acids, Bases, and Salts 5. Oxidation Reduction Sub-Organizers A, B, C D, E, F G, H, I J, K, L, M, N, O, P, Q, R S, T, U, V, W Part A: Multiple Choice Q K C S CO PLO Q K C S CO PLO 1. A U 1 1 A1 5. B K 1 4 K1. C K 1 1 A6 6. A U 4 K8 3. C U 1 1 B5 7. A K 1 4 L 4. B U 1 1 B6 8. D U 4 L1 5. B U 1 1 C5 9. D K 1 4 M 6. C H 1 C4, D 30. A K 1 4 N1 7. A U 1 D3 31. B U 1 4 N3 8. D U 1 E 3. B H 4 O3 9. B H 1 E3 33. B U 1 4 O4 10. D U D7 34. C H 1 4 P1 11. D U 1 F1 35. D U 4 P3 1. B K 1 F 36. D K 1 4 Q 13. C U 1 F4 37. C K 1 4 R1 14. A U F5 38. D K 1 5 S5 15. B K 1 3 G 39. D U 5 S 16. B U 1 3 G8 40. C U 1 5 S6 17. B U 3 H1 41. C U 1 5 S6, U9 18. C U 1 3 H3 4. B K 1 5 U3 19. C U 1 3 H7 43. C H 5 U5 0. B K 1 3 I 44. D U 1 5 T1, U 1. B U 3 I3 45. D U 1 5 U. C U 1 3 I6 46. A H 1 5 U9 3. B K 1 4 J4 47. A U 5 U10 4. C U 1 4 J11 48. A U 1 5 W4 Multiple Choice = 60 marks (48 questions) 06chk - 1 - July 9, 00
Part B: Written Response Q B C S CO PLO 1. 1 U 3 1 A3. K 1 B9 3. 3 K D7 4. 4 U 4 F7 5. 5 U 3 3 E, H5 6. 6 U 3 3 I4 7. 7 U 4 4 J8, K8 8. 8 U 4 L1 9. 9 U 5 4 M3 10. 10 U 3 4 Q5 11. 11 U 4 5 T 1. 1 U 3 5 W1, W7 13. 13 H 5 S6, U9 Written Response = 40 marks Multiple Choice = 60 (48 questions) Written Response = 40 (13 questions) EXAMINATION TOTAL = 100 marks LEGEND: Q = Question Number K = Keyed Response C = Cognitive Level B = Score Box Number S = Score CO = Curriculum Organizer PLO = Prescribed Learning Outcome 06chk - - July 9, 00
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 reaction: (3 marks) Al( s) + 6HCl( aq) AlCl3 ( aq) + 3H( g) A 10. 0 g sample of Al reacts completely in excess HCl in 300. 0 s. What is the rate of production of H in mol s? 1mol mol Al = 10. 0g = 0. 370 mol Al 7. 0g mol H rate = = 0. 370 mol Al = 0. 556 mol H = change in moles time 0. 556 mol H 300. 0 s = 185. 10 mol H s 3 3 mol H mol Al ( Deduct 1 mark for incorrect significant figures. ) 3 marks 06chk - 3 - July 9, 00
. Using collision theory, give two reasons why reactions occur more rapidly at a higher temperature. ( marks) There is a greater fraction of collisions with sufficient energy. There are more frequent collisions. marks 06chk - 4 - July 9, 00
3. Chemical reactions tend toward a position of minimum enthalpy and maximum entropy. a) What is meant by the term enthalpy? (1 mark) Enthalpy is a measure of heat content. b) What is meant by the term entropy? (1 mark) Entropy is a measure of randomness. 06chk - 5 - July 9, 00
4. Consider the following: (4 marks) H( g) + Br ( g) HBr( g) Keq = 1. 0 Initially, 0. 080 mol H and 0. 080 mol Br are placed into a 4. 00 L container. What is the HBr [ ] at equilibrium? H + Br HBr [ I ] 0. 00 0. 00 0 [ C] x x + x [ E] 0. 00 x 0. 00 x x K eq HBr x [ H ][ Br ] = ( ) 0. 00 x = [ ] ( x) 0. 00 x ( ) = x = 0. 017 [ HBr]= x = 0. 05 M ( ) 1. 0 = 1. 0 4 marks 06chk - 6 - July 9, 00
5. Consider the following equilibrium and accompanying graph: ( ) + s aq + 3 aq Zn IO3 ( ) Zn ( ) IO ( ) [ IO 3 ] [ Ions] [ Zn + ] marks t 1 t t 3 a) Identify the stress applied at t 1. (1 mark) + More Zn ( aq) has been added. b) Complete the above graph from t 1 to t 3 for the [ IO 3 ]. ( marks) See graph above. 06chk - 7 - July 9, 00
6. Calculate the solubility of SrSO 4 in grams per litre. (3 marks) SrSO + 4() Sr ( ) + SO K Sr SO s aq 4 aq s s s + 4 34 10 7 sp = [ ][ ]=. 7 = 34. 10 Solubility = s = 58. 10 ( ) 4 4 183. 7 g Solubility in g L = 58. 10 mol L mol = 011. gl M 3 marks 06chk - 8 - July 9, 00
7. The cyanide ion, CN, is a Brønsted-Lowry base. a) Define Brønsted-Lowry base. (1 mark) A Brønsted-Lowry base is a proton acceptor. b) Write the equation representing the reaction of CN with water. ( marks) CN + H O HCN + OH marks c) Identify a conjugate pair in b) above. (1 mark) CN and HCN OR HO and OH 06chk - 9 - July 9, 00
8. Write an equation to show the ionization of water. ( marks) HO + ( ) HO ( aq) + OH ( aq) marks l 3 06chk - 10 - July 9, 00
9. Calculate the ph of 1. 50 M NH 3. (5 marks) + 3 4 NH + H O NH + OH [] I 150. 0 0 [ C] x + x + x [ E] 150. x x x marks K K b b 10. 10 = 56. 10 [ + NH ][ OH ] 4 = NH [ 3] = x 150. x 14 10 = 179. 10 x = [ OH ]= 518. 10 poh = 9. ph = 11. 71 ( Deduct 1 mark for incorrect significant figures. ) 3 5 marks 06chk - 11 - July 9, 00
10. Consider the following buffer equilibrium: (3 marks) + HF( aq) + H O ( l) H3O ( aq) + F ( aq) high concentration low concentration high concentration Using Le Châtelier s Principle, explain what happens to the ph of the buffer solution when a small amount of NaOH is added. + NaOH causes [ H 3 O ] to decrease. The equilibrium shifts right. The ph almost returns to the former value. 06chk - 1 - July 9, 00
11. Balance the following redox equation: (4 marks) + Ag + NO3 Ag + NO (acidic) + + ( ) 3 Ag Ag + 3e 3e + 4H + NO3 NO + HO 3Ag + NO + 4H NO + H O + 3Ag + + 3 marks (1 mark for each half-reaction) for balancing electrons for addition 06chk - 13 - July 9, 00
1. Draw a diagram of an operating electrolytic cell used to extract pure lead from an impure lead sample. Identify the electrolyte and the material used for the anode. (3 marks) 1 mark DC Power Source + Anode (impure lead) 1.0 M Pb(NO 3 ) 06chk - 14 - July 9, 00
13. A sample of copper is placed in HNO 3( aq) and another sample of copper is placed in HCl ( aq). 1 a) In which acid does the copper react? ( mark) Copper reacts in HNO 3( aq). 1 mark b) Calculate E for the reaction that occurs. ( 1 1 marks ) E is +06. volts 1 1 marks END OF KEY 06chk - 15 - July 9, 00