CHE 105 EXAMINATION II March 11, 2010 University of Kentucky Department of Chemistry

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1 CHE 105 EXAMINATION II March 11, 2010 University of Kentucky Department of Chemistry READ THESE DIRECTIONS CAREFULLY BEFORE STARTING THE EXAMINATION! It is extremely important that you fill in the answer sheet EXACTLY as indicated, otherwise your test may not be processed; ALL entries are to be made on SIDE 1 of the answer sheet. Use a #2 pencil (or softer); fill in the circles completely and firmly. Erasures must be complete. Use only the following categories: NAME: STUDENT NUMBER: TEST FORM: SPECIAL CODES: Print your name starting at the first space, LAST NAME first, then a space, followed by your FIRST NAME, then another space, followed by your MIDDLE INITIAL. Fill in the correct circles below your printed name corresponding to the letters of your name; for the spaces, fill in the top blank circle. This is VERY IMPORTANT! Under IDENTIFICATION NUMBER, put in your 8 DIGIT STUDENT ID NUMBER (do not use the 9 at the beginning of your number) beginning in column A and continuing through column H, column I will be blank, (do NOT use column J at this time); be sure to fill in the correct circles (a common error to be avoided is mistaking "0" for "1"). Fill in the "2" blank in the J column under IDENTIFICATION NUMBER (to indicate Hour Examination II). Use for course and section number; in positions K-P write in one of the following: Dr. H. Ades , Ms. E. Ferguson SIGNATURE: You MUST sign the examination answer sheet (bubble sheet) on the line directly above your printed name. Use your legal signature. Answering Questions: Starting with answer "1" on SIDE 1, fill in the circle indicating the one best answer for each of the 25 questions in this examination. Your score is the sum of the appropriate credit for each response. The day after the examination is finished, an examination key will be posted on Blackboard. Grading and Reporting: The examination scores will be posted in Blackboard as soon as possible after the examination. If an error has been made in scoring your answers, tell your instructor within 48 hours of the posting of your score. BE SURE THAT YOUR TEST HAS 25 QUESTIONS, A PERIODIC TABLE, AND ONE SHEET OF SCRATCH PAPER. You may NOT use your own scratch paper during this examination. Cell phones and pagers are to be turned off and out of sight during the exams.

2 1. Which of the following is a strong electrolyte in aqueous solution? A. NH 3 C. CO B. Sr(NO 2 ) 2 D. C 3 H 7 OH 2. In which one of the following does a precipitate form when the two aqueous solutions listed are mixed? A. potassium hydroxide and barium chloride B. calcium acetate and ammonium carbonate C. sodium phosphate and lithium sulfide D. silver nitrate and sodium fluoride 3. In which of the following reactions is the species that is boxed act as the Brønsted base? A. N H 4 (aq) + H 2 O(l) qe NH 3 (aq) + H 3 O + (aq) B. H 2 CO 3 (aq) + H 2 O(l) qe HCO - 2 (aq) + H 3 O + (aq) C. HSO - 4 (aq) + HClO 4 (aq) qe H 2 SO 4 (aq) + Cl - 4 O (aq) D. H 2 P - 2- O 4(aq) + NH 3 (aq) qe HPO 4 (aq) + NH + 4 (aq) What is the oxidation number of phosphorus (P) in the P 2 O ion? 7 A. +3 C. +7 B. +5 D Which of the following statements about the reaction below is correct? Zn + 2HCl ZnCl 2 + H 2 A. Zn is the reducing agent. C. H 2 is the oxidizing agent. B. HCl is oxidized. D. Zn is reduced.

3 6. Which of the following is an example of a disproportionation reaction? A. Cl 2 (g) + 2Br (aq) 2Cl (aq) + Br 2 (l) B. Mg(s) + 2H 2 O (l) Mg(OH) 2 (s) + H 2 (g) C. Cl 2 (g) + H 2 O(l) HCl(aq) + HClO(aq) D. S(s) + O 2 (g) SO 2 (g) 7. What is the molarity of 25.0 g of KOH in 594 ml of solution? A M C M B M D M 8. Which of the following sets of directions correctly describes the preparation of 0.50 L of 2.0 M H 2 SO 4 from an 18 M stock solution? A. Dilute 56 ml of 18.0 M H 2 SO 4 to a volume of 0.50 L B. Combine 56 ml of 18.0 M H 2 SO 4 with 0.50 L of water C. Dilute 56 ml of 2.0 M H 2 SO 4 to a volume of 0.50 L D. Dilute 18 ml of 18 M H 2 SO 4 to a volume of 0.50 L 9. A 25.0 ml, M NaF solution is mixed with 50.0 ml of 1.25 NaF solution. What is the concentration of the final NaF solution? A M C M B M D M 10. What is the volume of a M CuSO 4 solution that would react completely with 2.34 g of zinc? A ml C ml B ml D ml 11. What volume of a M H 2 SO 4 solution is needed to neutralize 40.0 ml of a M NaOH solution? A ml C ml B ml D ml

4 12. How many moles of chloride (Cl - ) are present in 90.4 ml of M BaCl 2 solution? A mol C. 155 mol B. 132 mol D mol 13. Which of the following statements about gases is false? A. All gases are colorless and odorless at room temperature. B. Gases are highly compressible. C. Gases expand spontaneously to fill the container they are placed in. D. Gases exert a pressure on everything they collide with. 14. If the pressure of a confined gas is doubled while the temperature changes from 150 o C to 5 o C, what change will be observed? A. The volume of the gas will double. B. The volume of the gas will decrease to about 1/3 of its original value. C. The volume of gas will increase to about 3 times its original value. D. The volume of the gas will decrease to half of its original value. 15. What pressure will 12.5 g of CO(g) exert in a 4.58 L tank at 53 o C? A atm C atm B atm D atm 16. A hypothetical compound has an empirical formula SCl 4. At 39 o C, g of the gaseous compound occupies a volume of 22.1 ml and exerts a pressure of 1.00 atm. What is the molar mass and the molecular formula of the gas? A. 174 g/mol, SCl 4 C. 348 g/mol, S 2 Cl 8 B g/mole, SCl 4 D g/mol, S 2 Cl A sample of SO 3 (g) completely decomposes to SO 2 (g) and O 2 (g) when heated. What is the partial pressure of SO 2 produced if the total gas pressure after the reaction is complete is 795 mmhg? 2SO 3 (g) 2SO 2 (g) + O 2 (g) A. 199 mhg C. 265 mmhg B. 398 mmhg D. 530 mmhg

5 18. Initially CO(g) [2.45 L, atm] and O 2 (g) [2.04 L atm] are separated in two different chambers connected by a valve. The valve is then opened, and the reaction is allowed to go to completion. What is the partial pressure of the CO 2 (g) that is formed in the reaction? Assume that the temperature remains constant at 25 o C. 2CO(g) + O 2 (g) 2CO 2 (g) initially 2.45 L 2.04L atm atm A atm C atm B atm D atm 19. Molecular nitrogen and molecular oxygen combine to form a gaseous product. Under the same conditions of temperature and pressure, it is found that two (2) volumes of N 2 react with five (5) volumes of O 2 to yield two (2) volumes of the product. What is the formula of the product? A. N 2 O 3 C. NO 5 B. N 5 O 2 D. N 2 O Which one of the following statements is incorrect regarding gases? A. Gases are most ideal at pressures that cause the density of the gas to be small. B. Gases are most ideal at high temperatures and when the volume of the gas is negligibly small compared to the volume of the container. C. Gases are most ideal at high temperatures and high pressures. D. Ideal gases do not exert attractive or repulsive forces with one another. 21. Which of the following gases diffuses the fastest? All are under the same conditions of temperature and pressure? A. N 2 O C. O 3 B. CF 4 D. SO 2

6 22. Which one of the following statements is correct regarding the figure below: Energy 2 Al (s) + Fe 2 O 3 (s) Al 2 O 3 (s) + 2 Fe (l) A. The enthalpy change is zero. B. The reaction would have a positive H o. C. The reaction is an exothermic reaction. D. The reaction will absorb heat from the surroundings. 23. The work done to compress a gas is 225 J. As a result, 148 J of heat is released to the surroundings. What is the change in energy of the gas? A. 373 J C. 77 J B. 77 J D. 373 J 24. In which of the reactions below is E = H? All are at 25 o C and 1 atm. A. 3H 2 (g) + N 2 (g) 2NH 3 (g) C. 3O 2 (g) 2O 3 (g) B. C(s) + CO 2 (g) 2CO(g) D. N 2 (g) + O 2 (g) 2NO(g) 25. What is the heat evolved when 42.7 g of NH 3 (g) reacts according to the reaction below? 4NH 3 (g) + 5O 2 (g) 4NO(g) + 6H 2 O(g) H = 904 kj/mol A kj C. 904 kj B. 568 kj D kj

7 CHE 105 Exam 2 March 11, 2010 Question Corrrect Answer B B A B A C D A D B C A A B D C D B D C A C C D B Partial Credit