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Practice Exam 2 2009.pdf

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Department
Chemistry
Course Code
CHM 2046
Professor
Christou

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CHM2046 Exam 2 March 9, 2006 Please bubble in A, B or C as the test form code at the top right of your answer sheet. VERSION 0 For this version the correct answer to each question is a. 1. Predict the sign of ΔSº rxnfor the following reaction: 2 C (s) + O 2g) → 2 CO (g) a.positive bd. oennds ΔS univ c.negative d. cannot be predicted e.zero 2. What is the solubility of the salt M X2(c3ntaining M and X ions) if its K = 2.6 x sp ? -4 -2 a. 7.5 x 10 M b. 1.3 x 10 M1 -1 c. 1.9 x 10 -4 d. 2.6 x 10 M e. none of these 3. Addition of which of the following very soluble salts is most likely to increase the solubility of MgCO in 3ater? a.NH 4Cl bK. Cl c.Na 2O 3 dM. gI 2 e.NaNO 3 4. Which of the following substances will have the greatest molar entropy? a.C 3H 8g) bC. H 4 (g) c.C 6H 6l) dC. 2H 6g) e.C 4H 10) 5. Which of the following is always true for a spontaneous reaction? a. none of these b. ΔS surr 0 c. ΔS rxn> 0 d. ΔS < 0 rxn e. ΔS univ ΔS rxn+ ΔS surr 6. A solution is prepared that contains [Pb 2+ (aq)] = 1.4 x 10 M, and [I (aq)] = 2.0 x 10 M. -4 -9 Will a precipitate of PbI 2s) form? (K for spI is 7.92x 10 ). a.no b. none of these c. only if Na + (aq) ions are also added dy. es e. cannot be determined 7. The solubility product expression (K sp) for BaF 2s) in water is: a.K = [Ba (aq)][F (aq)] 2 sp b. none of these c.K sp = [Ba (aq)][F (aq)] dK. = [Ba (aq)][F (aq)] /[BaF (s)] sp 2+ - 2 e.K sp = [Ba (aq)][F (aq)]/[BaF (s)]2 8. Calculate the pH when 100 mL of 0.100 M Ca(OH) solution is added to 200 mL of 0.200 2 M HCl solution. a.1.18 b7. .00 c.1.00 d0. .88 e. none of these 9. The following reaction has ΔSº rxn= 197.9 J/K and ΔHº rxn= 49.7 kJ. Is the reaction spontaneous as written? A (g) + B (g) → products a. cannot be determined without the temperature by. es c.no df. nly ΔS < 0 univ ef.only ΔS univ 0 10. Addition of which of the following salts is most likely to decrease the solubility of MgCO 3 in water? a.Na 2CO 3 bK. Cl c.NaNO 3 dK. I e.NH 4l 11. What is the solubility of BaF (s) in a 0.10 M solution of NaF? (K of BaF (s) = 1.5 x -6 2 sp 2 10 ). a. 1.5 x 10 M b. 1.5 x 10 M -3 c. 7.2 x 10-4 d. 7.2 x 10 M e. none of these 12. For which of the following changes is ΔSº sysnegative? a.AlCl 3(s) dissolving in water b. a solid warming from 10 ºC to 20 ºC c. a tennis ball falling d. ice at 0 ºC melting to water at 0 ºC e. none of these 13. Calculate ΔSº for the reaction: H 2(g) + Cl 2g) → 2 HCl (g) Sº values (J/mol.K): H 2 (g) = 130.6; Cl2(g) = 223.0; HCl (g) = 186.8 a/K0.0 J/K.84 c. none of these Jd/. 54 e.1/K6.8 14. At the equivalence point of the titration of a 0.15 M NH 3solution with 0.15 M HCl solution, the pH will be: a. less than 7.00 b7. .00 c.gteaner d. cannot be determined e. none of these 15. Predict the sign of ΔSº rxnfor the following reaction: H 2g) + 2 O (g3 → 2 O (g) 2 H O (l) 2 2 a.negative bp. ositive c.zero d. cannot be predicted e.deoennds ΔHº rxn 16. Which of the following acids is best suited for preparing a buffer solution with pH = 5.00 and a high buffer capacity: C H
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