exam 3 08 spring

exam 3 08 spring - CHE 107 EXAMINATION III 10 April 2008...

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Unformatted text preview: CHE 107 EXAMINATION III 10 April 2008 University of Kentucky Department of Chemistry READ THESE DIRECTIONS CAREFULLY BEFORE STARTING THE EXAMINATEON! 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 l of the answer sheet. Use a #2 pencil (or softer); fill in the circies completely and thinly. Erasures must be complete Use only the following categories: Print your name starting at the first space, LAST NAME first, then a space, foliowed 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. STUDENT This is VERY IMPORTANT! Put in your 8 DIGIT NEW STUDENT ID NUMBER (do not NUMBER: 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) under IDENTIFICATION NUMBER; be sure to fill in the correct circles (a common error to be avoided is mistaking "0" for "1"). TEST FORM: Fill in the "3" blank in the 3 column under IDENTIFICATION NUMBER (to indicate Hour Examination ill). SPECEAL Use for course and section number; in positions Kvl’ write in one of the following: CODES: 107—003, 002 Dr. Woodruin 107—003, 004 Dr. Bramweil 10740] Dr. Ades 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 i, 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. Soon after the examination is finished, an examination key will be posted on Blackboard shortiy after 9:15 PM. Grading and Reporting: The examination scores wiEl be posted in Blackboard within 96 hours after the examination. If an error has been rnade in scoring your answers, tell your instructor within 48 hours of the posting of your score. BE SURE THAT YOUR TEST HAS 25 UBSTIONS A PERIODIC TABLE AND ONE SHEET OF SCRATCH i’APER. 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. W CHE 107 EXAMINATION III . 10 April 2008 University of Kentucky Department of Chemistry W Name: SID: Seat No: Room: 1. Which of the following combinations cannot be a buffer solution? A. HCN and KCN c. NaHzl’O4 and NaZHPO4 B. HF and KF D. HNO3 and KNO3 2. When Ca(NOz)2(aq) is added to 0.10 M HNO2 A. the percent ionization of HNO2 will increase. 13. the solution will be more acidic. C. the pH wili increase. D. the percent ionization will be unchanged. 3. What is the pH of a solution that is 0.50 M in aniline, C6H5NH2, and 0.75 M in anilinium chloride, C6H5NH3C1? Kb for aniline m 3.8 X 10~10 A. 4.40 B. 9.42 C. 4.58 D. 4.76 4. How many moles ofNaNO2 should be added to 100.0 1111. of 0.15 M ENG2 to produce a buffer with pH 3 4.65? Ka for HNO2 = 4.5 X 10”"L A. 0.3011110110211002 C. 2.0 moiNaNO2 B. 3.5 mol NaNO2 D. 15 molNaNO2 5. What is the pH of a solution formed by the addition of 10.0 mL of 0.100 M NaOH to 40.0 mL of 0.100 MHCN? Ka for HCN = 4.9 X 1.04” A. 9.79 B. 8.83 C. 8.71 D. 9.91 6. What is the pH at the equivalence point when 50.0 mL of 0.100 M HNO2 is titrated with 0.250 MKOH? Ka for HNO2 m 4.5 X 10““3 A. 8.10 B. 7.52 C. 2.25 D. 11.75 7. The indicator Hln has a pKa value of 5.5 X 10‘s. The acid form (Him) is blue, the ionized form In“ is yellow. The solution will be green at which pH? A. 1.50 B. 3.25 C. 4.26 D. 7.00 8. 100. mL of3.00 X 10“3 MPb(NO3)2 is added to 400. l’l’lL of 5.00 X 10"3 MNaQSOr. Which of the following statements is correct? Ksp for PhSO4 = 1.8 X 10‘g A. No precipitate is formed because Q = 1.8 X 10””). B. No precipitate is formed because Q < K513. C. Yes, PbSO4 precipitates and Q = 1.5 X 10‘5. D. Yes, Pbso4 precipitates and Q m 2.4 x 10—6. 9. The molar solubility of (3an = 2. ES X it)”4 M. What is Ksi3 for Can? A. 4.62 X 10—8 B. 1.85 X 10"” C. 3.98 X 10”“ D. 6.36 X i0“m 10. The solubility product for chromiumflll) fluoride is Ksp = 6.6 X 10"”. What is the molar solubility of chromiumflll) fluoride in a 0.300 M NaF solution? A. 2.4 >< 10‘9M C. 1.6 X EOWGM B. 2.2 ><10"“‘°M D. 1.2 810‘3M 11. Which of the following salts wiil be more solubie in an acid than in water: AgCl, Fe(OH)Z, Nith2 ? A. AgCl C. l"e(0H)2 B. AgCi and Fe(Ol-I)2 D. lie(OH)2 and NiNO2 12. Which of the following statements is true in order for a process to occur spontaneously? A. The entropy of the system and of the surroundings must both increase. B. The entropy of the system and of the surroundings must both decrease. C. The entropy of the surroundings must increase if that of the system decreases. D. The reaction must be exothermic. 13. (31301-102) will spontaneously freeze when placed in a liquid N2 bath. One may conclude that: A. AS 0. universe < B. AS is more positive than Assystem is negative. surroundings C. Both AS and AS are positive. surroundings 33' ASsurroundings < 0‘ system 14. Which of the following statements is not true? A. The third law of thermodynamics states that, “the entropy of a pure, perfect crystal is zero at G K. 8. Absolute values are not available for free energy, enthalpy, and internai energy. C. Entropy is an extensive property (varies with the size of the sample). D. The more complex the molecule, the smaller is its standard molar entropy. l5. i6. l7. l8. l9. Calcuiate the standard free energy change for the following reaction, given the values in the table provided. 2M5) + 3 2110(3) ——> A1203(s) + 3 Zn(s) Zn0(s) w318.2 kJ/rnol B. ~621.8kJ C. 714.9kJ A. ~1894.6 k3 D. More data is needed. The reaction (3(5) + 1420(3) v——‘ C065) "i" 1512(8) is endothermic. Which of the following statements is true? A. The forward reaction is spontaneous at all temperatures. B. The forward reaction is never Spontaneous. C. The forward reaction is spontaneous at high temperatures only. D. The forward reaction is spontaneous at low temperatures only. The absolute entrepy for iodornethane is 163 J/rnoleoK and the molar heat of vaporization for iodomethane at its normal boiling point of 424°C is 27.3 kJ/rnol. What is the entropy of vaporization (ASva ) for iodomethane? What is the free energy (AG) for the phase change for iodomethaiiie‘? A. AS = 24.5 J/rnole-K, AG =15 k] C. AS = 51.4 k] ,AG = 787 kJ moie- K B. A8: 86.5 J/rnoleK, AG : 0 D. AS m 5.50 M , AG : 32.8 M mole K What is AG“ for the following reaction at 25°C? BaF2(S) # Ba2+(aq) + 2 F“(aq), ng=4.0 X 10”“ A. 0.531(J/m01 B. 4.6 kJ/mol C. 49 kJ/inol D. 59kJ/mol When the following redox reaction is balanced with the smallest whole numbers, how many electrons are transferred? MnOflaq) + Sn2+(aq) W} Mn2+(aq) + Sn(s) B. 3 C. S D. 16 20. 21. 22. 23. 24. 25. For the galvanic cell at 298 K: Pt(s)|H2(l atm)|H"’(1 M)!|Cu2+(1 M)lCu(s) Which statement is false? A. The cell is in the standard state. B. The Pt is oxidized at the anode. C. The half ceil reaction at the cathode is Cu“ + 2 e“ -~+ Cu(s). D. The anode is a SHE (standard hydrogen electrode). Which of the following is the strongest reducing agent under standard state conditions given the reduction potentials below? Half—reaction E°(V) 85(9) + 2e’ “mi 2 Br”(aq) $1.07 Niz+(aq) + 2ew -—+ Ni(s) Mons A. Br2 B. Br“ C. Ni” D. Ni At 25°C, what is the emf of the cell: Pt(s)ll-12(2 atm)|H+(pH a 1.00)!§Pb2+(0.20 M) le(s) The standard emf is 0.13 V. A. 0.18V B. 0.13V C. 0.16V D. 0.08V The mercury battery, ‘ Zn(Hg)(S) + HgO(s) we moo) + Hg(0), has a constant voltage with a long life. Which of the following will explain this? A. The battery can be recharged. B. The concentrations of the reactants and products are constantly replenished. C. Since the reactants and products are solids and liquids, 13:63 m can and the ceil voltage is constant. D. The Eu.“ is dependent on the concentration of HgO and Zn(Hg). An aqueous solution of KZSO4 is electrolyzed. What are the likely products formed at the electrodes? A. anode — OZ; cathode - H2 C. anode — H2; cathode - K B. anode - S; cathode - K D. anode -— K; cathode — 02 The half~reaction at an electrode is Ag + e" m“) Ag(s). Caiculate the number of grams of silver that can be produced by supplying a current of 0.75 A for 1 hour. A. 0.50g 13. 3.0g C. 0.955g D. 291kg ...
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This note was uploaded on 10/12/2010 for the course CHE 150 taught by Professor Bonner during the Spring '10 term at Kentucky.

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exam 3 08 spring - CHE 107 EXAMINATION III 10 April 2008...

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