University of Waterloo DEPARTMENT OF CHEMISTRY CHEM 123 Test #1 Wednesday, February 13, Name (Print in ink!):

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1 University of Waterloo DEPARTMENT OF CHEMISTRY CHEM 123 Test #1 Wednesday, February 13, 2008 This is test version 002. Fill in ovals 002 for the Card Number (or Test Master) on your computer answer card. Name (Print in ink!): First name Surname Student Number: Signature: Aids Allowed: Time Allowed: Electronic Calculator 50 minutes Instructions: 1. The instructors names and section numbers are given below. Circle your instructor s name and section number now. T. Leung Section 006 8:30 am D. Gilbert Section 001 9:30 am M. Gauthier Section :30 am C. Bissonnette Section :30 am D. Gilbert Section :30 pm 2. Print your name and other information in the top right corner on the front of the computer card. 3. Fill in your ID number, Section Number and your test version in the designated fields. 4. Use a pencil to fill in the ovals on the computer card. Make sure any erasures are complete and clean. If you need a pencil, raise your hand and ask for one. 5. This test booklet has 13 questions and 7 pages (including this Cover Page and the Data Sheet). Check now to ensure that no pages are missing. If pages are missing, raise your hand and ask for a new test booklet. 6. There is only one correct answer for each question. Circle A, B, C, D or E on this booklet. When you have finished, transfer your answers to the computer card by filling in the appropriate oval (A,B,C,D or E) in the column for that question on the card. 7. Attempt all questions. No marks are deducted for wrong answers. Do all rough work on this test booklet. Scrap paper is not permitted. 8. At the end of the test, turn in this test booklet and your computer card, and leave immediately. Note: The last page is a DATA SHEET. You may tear it off. 1

2 [1] The triple point of iodine is at 90 torr and 115 C. This means that liquid I 2 A. Is more dense than I 2 (s) B. Can exist at pressure of 10 torr C. Cannot exist above 115 C D. Cannot exist at 1 atmosphere pressure E. Cannot have a vapour pressure less than 90 torr [2] Which of the following molecules can form hydrogen bonds? A. PH 3 B. HOCl C. GeH 4 D. H 2 S E. HBr [3] When a liquid is in dynamic equilibrium with its vapour at a given temperature, which of the following condition(s) will exist? I. There is no transfer of molecules between liquid and vapour. II. The vapour pressure has a unique value. III. The opposing processes, liquid vapour and vapour liquid, proceed at equal rates. IV. The concentration of vapour is dependent on time. A. I B. II and IV C. II and III D. I, II, and III E. None of the above [4] Given that ΔH vap for water is 40.7 kj/mol, what is the vapour pressure of water at 37 C? (The normal boiling point of water is 100 C.) A torr B torr C torr D torr E torr 2

3 [5] Which of the following statements is (are) FALSE? I. For a face-centered cubic unit cell, the radius of the atom in the unit cell is ( 2/4)L, where L is the length of an edge of the unit cell. II. A simple cubic unit cell has two atoms per unit cell. III. The packing efficiency in a face-centered cubic structure is the same as a hexagonal closest packed structure. A. I and II B. I, II, and III C. I D. II E. III [6] Elemental magnesium crystallizes in a face-centered cubic lattice. The density of magnesium is g/cm 3. What is the edge length of the Mg unit cell? A. 643 pm B. 573 pm C. 453 pm D. 335 pm E. 904 pm [7] Consider the reaction: 2NH 3 (g) N 2 (g) + 3H 2 (g). If the rate Δ[H 2 ]/Δt is mol L -1 s -1, then Δ[NH 3 ]/Δt is A mol L -1 s -1 B mol L -1 s -1 C mol L -1 s -1 D mol L -1 s -1 E mol L -1 s -1 3

4 [8] The oxidation of the iodide ion by ferricyanide occurs by the following reaction: Initial rate experiments yield the following data: What is the empirical rate law? A. Rate = k[fe(cn) 3 6 ][I ] 2 B. Rate = k[fe(cn) 3 6 ][I ] C. Rate = k[fe(cn) 3 6 ] 2 [I ] D. Rate = k[fe(cn) 3 6 ] 1 [I ] E. Rate = k [I ] 2Fe(CN) I 2Fe(CN) I 2. [Fe(CN) 3 6 ] 0 [I ] 0 Initial Δ[ I 2 ]/Δt M M mol L -1 s M M mol L -1 s M M mol L -1 s -1 [9] The reaction 2A + B C has the following proposed mechanism: Step 1: A + B º D Step 2: D + B º E Step 3: E + A C + B (fast equilibrium) (fast equilibrium) (slow) If step 3 is the rate-determining step, then the rate of formation of C should be: A. k[b][d] B. k[a][b] 2 C. k[a] 2 [B] D. k[a] 2 [B] 2 E. k[a][b][d] 2 4

5 [10] The rate constant for the second order reaction: 3A 4B is L mol -1 min -1. How long will it take the concentration of A to drop from 0.75 mol L -1 to 0.25 mol L -1? A min B. 444 min C. 180 min D min E min [11] Based on the reaction coordinate diagram shown below, which of the following statements is (are) TRUE? I. Compound III represents the reaction intermediate. II. Compounds II and IV are transition states. III. The step I III is the rate-determining step in the mechanism. II IV I III V A. I B. II C. III D. I and II E. I,II, and III Reaction Progress 5

6 [12] The rate law for the reaction: C 2 H 4 Br 2 + 3KI C 2 H 4 + 2KBr + KI 3 is given by: Rate = k[ki][c 2 H 4 Br 2 ] 2. What are the correct units for the rate constant k? A. s 1 B. L 3 mol 3 s 1 C. L 2 mol 2 s 1 D. L mol 1 s 1 E. mol L 1 s 1 [13] Which of the following statements is (are) FALSE? A. I and II B. II and II C. I D. II E. III I. The greater the energy of activation, E a, the faster will be the reaction. II. An elementary reaction is a simple, one-step process. III. All bimolecular elementary steps are second-order reactions. 6