1 Your full name (PLEASE PRINT) First hour test page 1 of 5 September 25, 2008 Your scheduled Tuesday quiz section (please circle) B hr E hr

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1 1 CHEM 111 Your full name (PLEASE PRINT) First hour test page 1 of 5 September 25, 2008 Your scheduled Tuesday quiz section (please circle) B hr E hr Your scheduled Tuesday quiz instructor: Make sure your test has FIVE pages---notify us immediately if it does not. Do NOT detach pages from the staple. You may use a writing implement, hand-calculator, and your Periodic Table (unmarked, honor code) as obtained in this course. NO scratch paper is permitted! As requested of the faculty by the Student Executive Committee, students must sit in every other seat during the test. The PROPER METHOD (i.e., Problem Set 0) must be shown clearly on all problems, and final answers must be expressed in appropriate form. Pay attention to dimensions!! When blanks for answers are provided, write your answer to be graded in the blank---we may not grade answers written in other locations! For the purposes of this test, represent hydronium ion as H 3 O + and not as H + (aq). 1. (7 pts) Please fill out the table below according to the method illustrated in P.S. 10. F Xe FF F central e - pairs to be arranged around Xe, e - pair shape? (sketch & name) molec. shape? (sketch and name) formal charges? how many π-bonds likely? resonance? drawing correction? 2. (8 pts) Use the "aufbau" and other knowledge you possess to give the actual array of electrons for the following species: A. Give SHORT-FORM ELECTRON CONFIG. B. Give ELECTRON DOT PICTURE 26Fe 79Au + 3. (8 pts) Define the following terms briefly and accurately ACCORDING TO YOUR LECTURE NOTES (do NOT illustrate them). Conjugate acid: Hard Lewis acid: Polarizability: (d) Electronegativity:

2 4. (14 pts) Show by appropriate formula(s) what species are present after each of the following bulk substances are mixed (individually) with water. Clearly distinguish between ions, molecules, and solids in the final aqueous mixtures. barium perchlorate (NH 4 )HSO 3 CH 3 OH 2 H 2 SO 4 aluminum chromate Ca 3 [Fe(CN) 6 ] 2 HCl 5. (25 pts) The following pairs of substances were first, as separate substances, mixed with water. Then the two aqueous mixtures were combined with thorough stirring. For each pair: & show by appropriate formula(s) what would be present in the separate mixtures; and then deduce and write the balanced chemical equation for the reaction(s) which occur(s) when the two mixtures are combined. If no reaction occurs upon mixing, write NR (No reaction!) sodium monohydrogensulfate and strontium hydroxide NiCl 2 and sodium hydroxide 5. (Continued use same instructions as previous page)

3 3 sodium sulfate and HI calcium chlorate and lithium nitrate FeSO 4 and six equivalents of ammonia 6. (6 pts) g g = 37 s 34.4 s = 45 m + 8 km = 7. (6 points) The figure at right is a mass spectrum for (circle one): C 2 H 4 O 2 (acetic acid) or CH 2 O 2 (formic acid). Briefly and grammatically explain your answer to part. What is the source of the peak at 15? (d) For a mixture analyzed by thin layer chromatography, the compound less strongly attracted to the stationary phase will spend the time adsorbed on the stationary phase and have the R f value. (Circle one below.) A. least, smallest B. least, largest C. most, largest D. most, smallest

4 8. (20 pts) Here is some useful information about bromine: 1st ionization energy = kj/mole; 2nd ionization energy = kj/mole; atomic radius = 114 pm; ionic radius (1- ion) = 1.82 Å; ionic radius (1+ ion) = 0.74 Å; electron affinity = kj/mol; energy required to separate covalently bonded Br 2 into Br atoms infinitely far apart 193 kj/mol [ k in the Coulomb s law equation = x J. m; by definition 1 Å = 1 x m] What would ΔE be for taking two Br atoms infinitely far apart and converting them into Br + and Br - infinitely far apart? 4 What would r e be for (Br + )( Br - ) in contact? What would ΔE Coul be in kj/mol if Br + and Br - infinitely far apart became ionically bound (Br + )( Br - ) in contact? (d) What would the difference in potential energy be between the lowest energy point on the curve for neutral Br atoms coming together to form covalently bonded Br 2 and the lowest energy point on the curve for Br + and Br - infinitely far apart coming together to form ionically bonded (Br + )( Br - )? (e) Will Br 2 be covalently bonded Br atoms or ionically bonded (Br + )( Br - )? Briefly why (your answer should involve numbers)? 9. (6 pts) Carbonic anhydrase is an enzyme critical to the transport of CO 2 in the body. It functions by accelerating by over a million-fold the reaction between water and CO 2, which, at physiological ph (acid/base)

5 conditions, produces HCO 3 -, rather than carbonic acid, as a product. At the enzyme active site, a Zn 2+ ion is complexed by four ligands: 3 nitrogen atoms from 3 different histidine imidazole rings and a hydroxide ion. The enzyme active site has been successfully modeled with tris-pyrazolylborate zinc(ii) complexes. Circle the letter of any true statements that follow: Zn 2+ has 8 d-electrons Zn 2+ is acting as a Brønsted base. Zn 2+ is acting as a soft Lewis acid. (d) All by itself, HCO 3 - spontaneously breaks down into H2 O and CO 2. (e) The nitrogen atoms are acting as intermediate Lewis acids. (f) The hydroxide is acting as a hard Lewis base. (g) In an aqueous solution of HCO 3 -, the HCO3 - would function as a weak Brønsted acid if an aqueous solution of hydroxide ion was added. 5 PLEDGE: I have neither given nor received any unacknowledged aid on this test. Signed,