Name Bubble on your scan sheet the Test Number and Test Form shown on the next page!! Instructions Principles of Chemistry II (3150:153-004) EXAM I Tuesday, 3:15PM EXAM FOR PRACTICE USE SPRING 2018 Answers at end February 28, 2017 205 1. Each student is responsible for following instructions. Read this page carefully. 2. Enter your name on this page and on your computer answer sheet. 3. CODE your name (LAST NAME FIRST) on the computer answer sheet using an ordinary (No. 2) pencil. It is very important to code the information correctly!! Use your full name as it is in UA s records, not any nickname. 4. Put all calculations on the examination pages or scratch paper. Do not make any extra marks on the computer answer sheet!! 5. This exam consists of 39 multiple-choice questions worth 5.5 points each. For each multiple-choice question, choose the ONE best or correct answer and write it both on your exam paper and on the answer sheet. The computer answer sheet is the only one that will be graded! 6. Unless otherwise stated in a question: atoms and molecules are in the ground state; solutions are aqueous; and substances are at 25 C and 1 atm (~100 kpa). 7. This exam booklet consists of 6 pages (including this one), a Periodic Table/Formula Sheet, and a sheet of blank paper. Please check to be sure that you have them all! KEEP YOUR EXAM BOOKLET AND ANSWER SHEET COVERED TO PROTECT THE INTEGRITY OF YOUR WORK! PROHIBITED DURING EXAM: food and drink, cell phones, pagers, laptops, PDAs, headphones, hats worn low over the eyes Please put these items away until you have left the room. important information about bubbling your scan sheet: Enter your first and last names as far to the LEFT as possible in the respective fields. In the STUDENT ID field, enter two zeros, then your 7-digit UA ID number. You MUST bubble 3150:153-004 in the Dept/Course/Section fields. You MUST bubble the TEST FORM shown above in the Test Form field. FAILING TO BUBBLE EVERYTHING CORRECTLY WILL PREVENT OR SIGNIFICANTLY DELAY PROCESSING OF YOUR EXAM!! If you erase and change an answer, please try using the white plastic eraser at the front of the room to remove the old mark. The scanner is VERY sensitive to erased marks! Thanks. The Management
On your answer sheet, right now, enter TEST FORM A and TEST NUMBER 1 on your scan sheet. Your exam can not be graded without this information. 1. A commercial vinegar was found to contain 4.1% by mass of acetic acid (CH3COOH) in water. What is the molarity of the solution? The density of the solution is 1.01 gml 1. (A) 0.38 M (B) 0.69 M (C) 1.1 M (D) 4.1 M (E) 41 M Molar Mass/gmol 1 CH3COOH 60.05 2. A beaker containing 200 ml of a saturated solution of KI (with some solid KI at the bottom of the beaker) at 25 C is left standing to evaporate water at constant temperature at until there is 100 ml of solution in the beaker. Compared to the original concentration, the final concentration of KI is (A) higher. (B) lower. (C) the same. (D) impossible to predict. 3. A beaker contains a saturated solution of sodium carbonate (Na2CO3) in equilibrium with solid sodium carbonate at the bottom of the beaker. A small amount of sodium carbonate containing only radioactive 14 C is added to the solid at the bottom of the beaker. A week later, where would radioactive 14 C be found? (A) in the solid only (B) in the solution only (C) in both the solid and solution Questions 4 10 involve this reaction and related information provided: SCl2(g) + 2C2H4(g) º S(C2H4Cl)2(g) KC = 1.44 10 1 @ 20 C ΔH RXN = 228 kj For Questions 4 8, determine the effect on [S(C2H4Cl)2] at equilibrium for each disturbance: disturbance effect on [S(C2H4Cl)2] 4. addition of Ar(g) (A) increase (B) decrease (C) no effect 5. increase in container volume (A) increase (B) decrease (C) no effect 6. decrease in temperature (A) increase (B) decrease (C) no effect 7. addition of SCl2(g) (A) increase (B) decrease (C) no effect 8. removal of C2H4(g) (A) increase (B) decrease (C) no effect 9. Which direction must the reaction shift to reach equilibrium if a reaction container were prepared with (C2H4) = 0.23 M, (SCl2) = 1.26 M, and (S(C2H4Cl)2) = 1.8 M? (A) right (B) left (C) neither; the reaction is already at equilibrium. 10. Which change would cause a change in the value of KC? (A) removal of C2H4(g) (B) addition of Ar(g) (C) increase in container volume (D) decrease in temperature 3150:153-004 Exam I 2
11. Solid AgCl (KSP = 1.8 10 10 ) would be most soluble in (A) 0.10 M KCl. (B) 0.10 M AgNO3. (C) pure water. 12. Consider these reactions and equilibrium constants: A + 2D º E 2D º R K2 E + X º Z + R K3 What is the value of the equilibrium constant for this reaction? A + X º Z (A) K1 K2 K3 (B) K1 H K3 K2 (C) K1 K2 K3 (D) K1 + K3 K2 (E) K1 + K2 + K3 13. Which acid is the strongest in aqueous solution? (A) HClO3 (B) HClO2 (C) HClO K1 14. What is the K expression for this reaction? 2KHCO3(s) º K2O(s) + H2O(g) + 2CO2(g) [K2O][H2O][CO 2] (A) K = [KHCO 3] 2 [K2O][H2O][CO 2] (B) K = 2 [KHCO ] 3 (C) K = [H2O][CO 2] 2 (D) K = [H2O][CO 2] 15. To the nearest whole ph unit, what is the ph of a 1.0 10 11 M HBr solution? (A) 1 (B) 3 (C) 7 (D) 11 16. If the ph of a solution increases by 3, the concentration of OH (A) increases by a factor of 3. (B) increases by a factor of 1000. (C) decreases by a factor of 1000. (D) decreases by a factor of 3. 17. What is the conjugate acid of HSO3? (A) H2SO3 (B) H2SO3 (C) SO3 (D) SO3 2 (E) H3O + 3150:153-004 Exam I 3
18. What does it mean when a substance is amphoteric? (A) It can act as a reducing agent or an oxidizing agent. (B) It can react with acids or bases. (C) It can form extended covalently-bonded chains of like atoms. (D) It forms only water-soluble compounds. 19. What is the ph of a solution with [OH ] = 1.0 10 4 M? (A) 10.00 (B) 4.00 (C) 4.00 (D) 10.00 (E) none of these 20. Which solution would have the highest ph? (A) 0.10 M HCl (B) 0.10 M HF (Ka = 7.2 10 4 for HF) (C) 0.10 M NH3 (Kb = 1.8 10 5 for NH3) (D) 0.10 M NaOH 21. Which solution would have the lowest ph? (A) 0.10 M NaNO3 (B) 0.10 M Ca(NO3)2 (C) 0.10 M Al(NO3)3 (D) all have the same ph. 22. Which solution would have the lowest ph? (A) 0.10 M NH4Cl (B) 0.10 M NH3 (Kb = 1.8 10 5 for NH3) (C) 0.10 M NaOH (D) all would have the same ph. 23. Which solution would have the larger percent dissociation? (A) 0.10 M HCOOH (Ka = 1.8 10 4 for HCOOH) (B) 0.10 M CH3COOH (Ka = 1.8 10 5 for CH3COOH) (C) both would have the same percent dissociation. (D) it is impossible to tell without additional information. 24. Would 0.10 M pyridinium formate solution be acidic, basic, or neutral? Kb = 1.8 10 9 for pyridine Ka = 1.8 10 4 for formic acid (A) acidic (B) basic (C) neutral 25. The ph at the equivalence point of a titration of a weak acid with a strong base is (A) less than 7. (B) equal to 7. (C) greater than 7. 26. If 2 drops of 1 M strong acid were added to 50 ml of a ph 5.60 buffer solution, the ph would (A) decrease significantly. (B) decrease slightly. (C) not change. (D) increase slightly. (E) increase significantly. 3150:153-004 Exam I 4
27. At 50 C, KW = 5.5 10 14. We can conclude that the ph of pure water at 50 C is (A) greater than 7. (B) equal to 7. (C) less than 7. 28. In a titration of a 20.00 ml of 0.10 M weak acid with 0.10 M strong base, when is the ph of the contents of the flask equal to the pka of the weak acid? (A) when 30.00 ml of base is added (B) when 20.00 ml of base is added (C) when 10.00 ml of base is added (D) just before any base is added (E) never 29. Calculate the ph of a solution prepared with 0.23 mol triethylammonium chloride ((C2H5)3NHCl) in 1.0 L of solution. The Kb of triethylamine ((C2H5)3N) is 5.2 H 10 4. (A) 0.64 (B) 1.96 (C) 3.28 (D) 5.68 (E) 12.04 30. What is [H3O + ] in a solution of butyric acid (Ka = 1.5 10 5 ) prepared by dissolving 0.10 mol of butyric acid in enough water to make 1.0 L of solution? (A) 1.5 10 6 M (B) 1.0 10 5 M (C) 1.2 10 3 M (D) 3.9 10 3 M 31. Identify the Lewis acid and the Lewis base in this reaction. Ag + + 2[:C N:] [:N C Ag C N:] Lewis acid Lewis base (A) [:C N:] Ag + (B) [:N C Ag C N:] [:C N:] (C) [:C N:] [:N C Ag C N:] (D) Ag + [:C N:] (E) none of these 32. What is the ph of a buffer prepared with 0.30 mol NaNO2 and 0.10 mol HNO2 in enough water to make 1.0 L of combined solution? Ka(HNO2) = 4.0 10 4 (A) 2.92 (B) 3.40 (C) 3.88 (D) none of these 33. What is the molality of a 10.0% by mass solution of CH3CH2OH? The density of the solution is 0.982 gml 1. (A) 2.13 m (B) 2.17 m (C) 2.41 m (D) 4.52 m (E) 4.69 m Molar Mass/gmol 1 CH3CH2OH 46.07 3150:153-004 Exam I 5
34. Which hydroxide is LEAST soluble in water? (A) Ba(OH)2: KSP = 5.0 10 3 (B) Ca(OH)2: KSP = 5.5 10 6 (C) Cd(OH)2: KSP = 2.5 10 14 (D) Zn(OH)2: KSP = 1.2 10 17 3150:153-004 Exam I 6
Answers (No Peeking) 1. B 2. C 3. C 4. C 5. B 6. A 7. A 8. B 9. B 10. D 11. C 12. B 13. A 14. D 15. C 16. B 17. B 18. B 19. D 20. D 21. C 22. A 23. A 24. A 25. C 26. B 27. C 28. C 29. D 30. C 31. D 32. C 33. C 34. D 3150:153-004 Exam I 7