CHE 105 EXAMINATION II October 13, 2011 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 answer sheet 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: SIGNATURE: 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. Woodrum 105-001, 105-005 Dr. Guzman 105-002 Dr. Soult 105-003, 105-004 Dr. Ladipo 105-006 Dr. Kuhler 105-007 Dr. Holler 105-401 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 30 questions in this examination. Your score is the sum of the appropriate credit for each response. On the day following the examination, 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 occurred in scoring your answers, inform your instructor within 48 hours of the posting of your score. BE SURE THAT YOUR TEST HAS 30 QUESTIONS, A PERIODIC TABLE, AND ONE SHEET OF SCRATCH PAPER. You may NOT use your own scratch paper during this examination. Cell phones, computer, and pagers are to be turned off and out of sight during the exam.
1. Calculate the molecular mass of fructose, C 6 H 12 O 6. A. 246.17 amu C. 164.16 amu B. 196.16 amu D. 180.16 amu 2. How many fluorine atoms are in 25.0 grams of SF 4? A. 1.18 10 24 atoms C. 5.57 10 23 atoms B. 1.39 10 23 atoms D. 3.48 10 22 atoms 3. Calculate the mass percent of Cl in RuCl 3. A. 51.27% C. 35.45% B. 55.46% D. 48.20% 4. For the equation: 2H 2 O 2 2H 2 O + O 2 Calculate the number of moles of oxygen gas that is produced from the complete decomposition of 30.0 g of H 2 O 2. A. 0.500 mole C. 2.00 mole B. 1.00 mole D. 0.441 mole 5. A hydrocarbon contains 82.66% carbon and the rest is hydrogen. Determine the empirical formula of the compound. A. C 2 H 5 C. C 3 H 8 B. C 2 H 6 D. C 4 H 10
6. A certain compound has an empirical formula NO 2. If the ratio of the molar mass to the empirical formula molar mass is 2:1, what is the molecular formula of the compound? A. NO 2 C. N 2 O 2 B. N 2 O 4 D. N 4 O 2 7. When the equation for the reaction of gaseous carbon dioxide with liquid water to produce aqueous glucose (C 6 H 12 O 6 ) and oxygen gas is balanced with the lowest whole numbers, what is the coefficient of oxygen? A. 1 C. 3 B. 6 D. 9 8. Nitrogen monoxide reacts with hydrogen to produce ammonia and water. Find the number of moles of hydrogen gas consumed when 9.4 moles of NH 3 is produced. 2NO(g) + 5H 2 (g) 2NH 3 (g) + 2H 2 O(g) A. 3.8 mol H 2 C. 24 mol H 2 B. 9.4 mol H 2 D. 47 mol H 2 9. Zinc metal reacts with silver nitrate according to the reaction: Zn(s) + 2 AgNO 3 (aq) Zn(NO 3 ) 2 (aq) + 2 Ag(s) Calculate the mass of Ag that forms when 3.00 g of zinc metal is placed in an aqueous solution containing 3.75 g of silver nitrate. A. 1.59 g C. 3.69 g B. 2.38 g D. 4.90 g
10. Adipic acid, H 2 C 6 H 8 O 4, is made commercially by reacting cyclohexane (C 6 H 12 ) with O 2 as shown below. 2C 6 H 12 (l) + 5O 2 (g) 2H 2 C 6 H 8 O 4 (l) + 2H 2 O (g) If 25.0 g of cyclohexane is the limiting reactant, and the mass of adipic acid obtained is 33.5 g, what is the percent yield of the adipic acid? A. 44.1% C. 77.2% B. 43.5 % D. 25.0% 11. What volume of 0.200 M NaCl contains 0.0100 moles of the solute? A. 0.0200 L C. 50.0 L B. 50.0 ml D. 20.0 ml 12. What volume of 2.00 M NaCl is required to prepare 250.0 ml of 0.150 M NaCl? A. 42.9 ml C. 24.6 ml B. 3.30 L D. 18.8 ml 13. Which of the following best describes what happens when a chromium(ii) bromide solution is mixed with a sodium carbonate solution? A. CrBr 2 (aq) + 2 NaHCO 3 (aq) Cr(HCO 3 ) 2 (s) + 2 NaBr(aq) B. Cr 3 Br 2 (aq) + Na 2 CO 3 (aq) Cr 3 CO 3 (s) + 2 NaBr(aq) C. CrBr 2 (aq) + Na 2 CO 3 (aq) CrCO 3 (s) + 2 NaBr(aq) D. No reaction occurs. 14. Predict the products of the reaction between aqueous solutions of Na 2 SO 4 and AgNO 3. A. NaNO 3 (s) and Ag 2 SO 4 (aq) C. Na 2 NO 3 (aq) and Ag 2 SO 4 (s) B. NaNO 3 (s) and Ag 2 SO 4 (s) D. NaNO 3 (aq) and Ag 2 SO 4 (s)
15. What is the balanced net ionic equation for the following reaction? CuBr 2 (aq) + 2 NaOH(aq) 2 NaBr(aq) + Cu(OH) 2 (s) A. Cu 2+ (aq) + 2 OH (aq) Cu(OH) 2 (s) B. Cu 2+ (aq) + 2 Br (aq) + 2 Na + (aq) + 2 OH (aq) 2 Na + (aq) + 2 Br (aq) + Cu(OH) 2 (s) C. 2 Br (aq) + 2 Na + (aq) 2 NaBr (aq) D. Cu 2+ (aq) + 2 Br (aq) + 2 Na + (aq) + 2 OH (aq) 2 NaBr (aq) + Cu(OH) 2 (s) 16. If 45.7 ml of 0.500 M H 2 SO 4 is required to neutralize a 20.0 ml sample of NaOH solution used in an analysis, what is the concentration of the NaOH solution? A. 4.56 M C. 2.29M B. 0.00456 M D. 0.00248 M 17. What is the oxidation number of manganese in KMnO 4? A. 2 C. +3 B. 0 D. +7 18. Which of the following is an oxidation-reduction reaction? A. H 2 SO 4 (aq) + 2NaOH(aq) Na 2 SO 4 (aq) + 2H 2 O(aq) B. Zn(s) + Cu(NO 3 ) 2 (aq) Cu(s) + Zn(NO 3 ) 2 (aq) C. NH 3 (aq) + CH 3 COOH(aq) NH 4 + (aq) + CH 3 COO (aq) D. KCl(aq) + AgNO 3 (aq) AgCl(s) + KNO 3 (aq) 19. Your local weather person announces that the barometric pressure is 30.14 inches of Hg today in Lexington. Convert this pressure to atm. A. 1.007 atm C. 3.966 10 2 atm B. 2.050 atm D. 2.974 10 4 atm
20. A balloon has a volume of 2.5 L at 20.0 C. At what temperature will it have a volume of 2.9 L if the pressure is held constant throughout the experiment? A. 23 C C. 67 C B. 17 C D. 24 C 21. Calcium carbonate decomposes upon heating according to the reaction: CaCO 3 (s) CaO (s) + CO 2 (g) When a sample of CaCO 3 (s) was completely decomposed, the CO 2 gas released was collected in a 250 ml flask and had a pressure of 1.3 atm at 31 C. Calculate the number of moles of CO 2 gas that was generated. A. 7.8 mol C. 0.12 mol B. 1.4 mol D. 0.013 mol 22. What is the density of carbon tetrachloride vapor at 714 torr and 125ºC? A. 4.42 g/l C. 3.50 g/l B. 15.4 g/l D. 7.0 g/l 23. A mixture of He, Ne and Ar has a total pressure of 1.6 atm and is found to contain 0.55 mol He, 0.94 mol Ne, and 0.35 mol Ar. What is the partial pressure (in atm) of each gas? He Ne Ar A. 0.88 1.50 0.56 B. 0.48 0.82 0.30 C. 5.4 3.1 8.4 D. 2.9 1.7 2.9
24. Consider the following combustion reaction CH 4 (g) + 2O 2 (g) CO 2 (g) + 2H 2 O(l) If 2.0 L of methane (CH 4 ) reacts with an excess of oxygen at STP, what is the theoretical yield of water, in grams? A. 4.0 g C. 18 g B. 3.2 g D. 32 g 25. Using the ideas of the Kinetic Molecular Theory, select the order of increasing pressure for the ideal gases below. Assume that all the gas samples are at the same temperature and that each of the containers has exactly the same volume. A. P b < P a < P c C. P a < P c < P b B. P a < P b < P c D. P c < P a < P b 26. Which of the following is false? A. Kinetic energy is the energy associated with the motion of an object. B. Chemical energy is a form of kinetic energy. C. Heat is the flow of energy caused by a temperature difference. D. Work is a force acting through a distance.
27. Heat released by a system and work done by a system on its surroundings are assigned a sign and a sign, respectively. A. negative; negative C. negative; positive B. positive; negative D. positive; positive 28. Calculate the change in the internal energy of the system for a process in which the system absorbs 140 J of heat from the surroundings and does 85 J of work on the surroundings. A. +55 J C. +225 J B. 55 J D. 225 J 29. Increasing amounts of greenhouse gases in the atmosphere contribute to global warming mainly by A. reacting with other gases in the atmosphere in exothermic reactions. B. altering the ph of the oceans so that they do no absorb as much heat. C. decreasing the efficiency of internal combustion engines so that more heat is released into the atmosphere. D. preventing heat from being radiated back into outer space. 30. Acetylene gas, C 2 H 2, undergoes combustion to form carbon dioxide and water. Which of the following statements is false? A. The reaction is a redox reaction in which oxygen is reduced. B. When the reaction occurs at STP, the total volume of all gases present decreases. C. As the reaction occurs, the system (reaction) gains energy and the surroundings lose the same amount of energy. D. If equal volumes of acetylene and oxygen are combined, acetylene is the limiting reactant.
CHE 105 FALL 2011 Exam 2 key 1. D 2. C 3. A 4. D 5. A 6. B 7. B 8. C 9. B 10. C 11. B 12. D 13. C 14. D 15. A 16. C 17. D 18. B 19. A 20. C 21. D 22. A 23. B 24. B 25. C 26. B 27. A 28. A 29. D 30. C