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• Students must immediately follow the invigilator’s order to stop writing at the end of the examination time and must not alter an Examination Booklet, Response Booklet or Answer She[r]
Chemistry 12 Examination Booklet 2007/08 Released Exam August 2008 Form A DO NOT OPEN ANY EXAMINATION MATERIALS UNTIL INSTRUCTED TO DO SO FOR FURTHER INSTRUCTIONS REFER TO THE RESPONSE BOOKLET Contents: 19 pages 50 multiple-choice questions Examination: hours Additional Time Permitted: 60 minutes © Province of British Columbia PART A: MULTIPLE CHOICE Value: 62.5% of the examination Suggested Time: 80 minutes INSTRUCTIONS: For each question, select the best answer and record your choice on the Answer Sheet provided Using an HB pencil, completely fill in the bubble that has the letter corresponding to your answer You have Examination Booklet Form A In the box above #1 on your Answer Sheet, fill in the bubble as follows Exam Booklet Form/ Cahier d’examen A B C D E F G H Consider the reaction: H2 (g) + I2 (g) 2HI(g) Which of the following would decrease the rate of reaction? A B C D an increase in [I2 ] a decrease in [HI] a decrease in [H2 ] an increase in temperature Consider the reaction: ZnS(s) + H2SO (aq) + O2 (g) ZnSO (aq) + S(s) + H2O() What would increase the fraction of successful collisions? A B C D I increasing temperature II increasing surface area of ZnS III increasing [H2SO ] IV adding a suitable catalyst I and II only I and IV only II and III only I, II, III and IV Chemistry 12 – 0808 Form A Page Consider the following two reactions occurring under the same conditions: I C2 H5Cl () C2 H4 (g) + HCl (g) Ea = 254 kJ II C2 H5 Br () C2 H4 (g) + HBr (g) Ea = 219 kJ Which of the following is correct? A Reaction I is faster because it has a higher E a B Reaction II is faster because it has a lower E a C Reaction I is slower because it is exothermic D Reaction II is slower because it is endothermic An uncatalyzed reaction has the following values for E a : E a (forward ) = 250 kJ E a (reverse ) = 100 kJ If a catalyst is added to the reaction, which of the following values could be correct? Page E a (forward ) ( kJ) E a (reverse) (kJ) H(forward ) ( kJ) A 50 200 150 B 50 200 +150 C 200 50 150 D 200 50 +150 Chemistry 12 – 0808 Form A Consider the following reaction mechanism: C 2H5HgI C2 H5Hg+ + I Step 1: C 2H5Hg+ + Cl Step 2: Particle C2 H5HgI + Cl C2 H5HgCl + I Overall Identify Particle and a reaction intermediate from the above mechanism Particle Reaction Intermediate A C 2H5Hg+ C 2H5HgI B C 2H5HgI C 2H5Hg+ C C 2H5HgCl I D C2 H5HgCl C 2H5Hg+ Consider the following PE diagram for a reversible reaction: 500 400 PE (kJ) 300 200 Progress of the reaction Which of the following correctly corresponds to the diagram above? PE of activated complex (kJ) E a (reverse) (kJ) H(forward ) ( kJ) A 150 200 + 50 B 200 150 50 C 450 150 + 50 D 450 300 + 50 Chemistry 12 – 0808 Form A Page Reacting systems naturally tend toward what changes in enthalpy and entropy? Page Change in Enthalpy Change in Entropy A decreasing increasing B decreasing decreasing C increasing increasing D increasing decreasing Chemistry 12 – 0808 Form A Use the following equilibrium to answer questions to 10 NH Cl(s) NH (g) + HCl (g) H = + 176 kJ Which of the following would cause a shift to the right? A adding NH Cl B removing NH C increasing pressure D decreasing temperature When HCl is added, how the concentrations of NH and HCl at the new equilibrium compare to the original equilibrium concentrations? [NH ] [HCl] A higher higher B higher lower C lower higher D lower lower 10 Solid NH Cl is added to the preceding equilibrium What will happen to the forward and reverse rates? Forward Rate Reverse Rate A increases increases B no change no change C increases decreases D decreases increases Chemistry 12 – 0808 Form A Page 11 Due to a change in temperature, a system at equilibrium shifts, causing the concentration of products to change Which of the following could be correct? A B C D [Products] Value of Keq I increases no change II increases increases III decreases decreases IV decreases increases I only II only I and IV only II and III only 12 Consider the following equilibrium: C(s) + H2O(g) CO(g) + H2 (g) Keq = 0.16 At equilibrium, there are 0.60 mol C, 0.30 mol H2O and 0.32 mol CO in a 1.0 L flask What is the equilibrium [H2 ] ? A 0.090 M B 0.15 M C D 3.5 M 5.9M 13 Consider the equilibrium: 2SO (g) + O2 (g) 2SO (g) Initially, 1.6 mol SO is placed in a 3.0 L container At equilibrium, [O2 ] = 0.15 M What is the value of Keq ? A B C D Page 0.26 1.2 4.0 43 Chemistry 12 – 0808 Form A 14 Consider the following equilibrium system: 2CH4 (g) C2 H2 (g) + 3H2 (g) Keq = 2.8 Initially, 0.4 mol of each substance is placed in a 1.0 L container Which of the following correctly describes this system as it approaches equilibrium? [C2 H2 ] Forward Rate A increases decreases B increases increases C decreases decreases D decreases increases 15 Which solution will have the greatest electrical conductivity? A 0.10 M HCl B 1.0 M LiOH C 2.0 M H 3PO D 2.0 M CH 3CH OH 16 What are the ion concentrations that result when 1.0 10 3 mol of K 3PO is dissolved to produce 1.00 10 L of solution? K + PO 43 A 3.0 10 5 M 1.0 10 5 M B 1.0 10 5 M 3.0 10 5 M C 7.5 10 4 M 2.5 10 4 M D 3.0 10 3 M 1.0 10 3 M Chemistry 12 – 0808 Form A Page 17 What happens when equal volumes of 0.2 M Na 2SO3 and 0.2 M CaS are mixed? A Only Na 2S precipitates B Only CaSO3 precipitates C Both CaSO3 and Na 2S precipitate D No precipitate forms 18 Consider the solubility equilibrium: 2 2+ SrCO3 ( s ) Sr ( aq ) + CO3 ( aq ) The addition of which of the following substances will cause the equilibrium to shift right? A HCl ( aq ) B SrCO3 ( s ) C Na 2CO3 ( aq ) D Sr ( NO3 )2 ( aq ) Page Chemistry 12 – 0808 Form A ... of the following 0.10 M solutions would have the lowest pH? A B HF NH C HNO3 D H CO3 Page 12 Chemistry 12 – 0808 Form A 32 Which of the following describes a solution of LiClO ( aq ) with respect... (reverse) (kJ) H(forward ) ( kJ) A 50 200 150 B 50 200 +150 C 200 50 150 D 200 50 +150 Chemistry 12 – 0808 Form A Consider the following reaction mechanism: C 2H5HgI C2 H5Hg+ + I Step... (reverse) (kJ) H(forward ) ( kJ) A 150 200 + 50 B 200 150 50 C 450 150 + 50 D 450 300 + 50 Chemistry 12 – 0808 Form A Page Reacting systems naturally tend toward what changes in enthalpy and entropy?