Oregon State University, Summer 2009 Chemistry 121 Final Exam, July 10 th, 10 am DO NOT OPEN THIS EXAM UNTIL INSTRUCTED. CALCULATORS ARE NOT TO BE SHARED. Instructions : You should have with you several number two pencils, an eraser, your notecard, your University ID Card, and a calculator. If you have other notes with you, place them in a sealed backpack and place the backpack OUT OF SIGHT. Fill in the front page of the Scantron answer sheet with your last name, first name, middle initial, and student identification number. Leave the class section number and the test form number blank. This exam consists of 25 multiple-choice questions. Each multiple-choice question has 5 points associated with it. Select the best answer by filling in the corresponding circle on the rear page of the answer sheet. If you have any questions before the exam, please ask. If you have any questions during the exam, please raise your hand to attract the attention of a proctor. The proctor will come to you. Open and start this exam when instructed. Present your ID card when submitting the exam. Place your openended portion of this exam in the appropriate stack. You may keep the this exam, so please mark the answers you selected on it. Scoring : 25 multiple-choice questions @ 5 pts each = 125 pts Information provided A periodic table, a list of polyatomic ions, solubility rules and a list of strong acids and bases, and oxidation number rules are provided on the next four sheets. Check to see that you have them. Conversion factors 1 L = 1000 cm 3 N A = 6.022 10 23 c = 3.00 10 8 m / s h = 6.626 10-34 J s Some possibly useful formulae: E = q + w H = q p E = q v w = - P V q = m C T For light waves : λ = c / ν E = h ν = h c / λ λ = h / m v
Group 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 1A 2A 3B 4B 5B 6B 7B 8B 1B 2B 3A 4A 5A 6A 7A 8A 1 2 1 H 1.00794 3 Li 6.941 4 Be 9.01218 KEY Atomic number! 1 Symbol! H Atomic mass! 1.0079 5 B 10.811 6 C 12.011 7 N 14.0067 8 O 15.9994 9 F 18.9984 2 He 4.00260 10 Ne 20.1797 3 11 Na 22.9898 12 Mg 24.3050 13 Al 26.9815 14 Si 28.0855 15 P 30.9738 16 S 32.066 17 Cl 35.4527 18 Ar 39.948 4 19 K 39.0983 20 Ca 40.078 21 Sc 44.9559 22 Ti 47.88 23 V 50.9415 24 Cr 51.9961 25 Mn 54.9381 26 Fe 55.847 27 Co 58.9332 28 Ni 58.69 29 Cu 63.546 30 Zn 65.39 31 Ga 69.723 32 Ge 72.59 33 As 74.9216 34 Se 78.96 35 Br 79.904 36 Kr 83.80 5 37 Rb 85.4678 38 Sr 87.62 39 Y 88.9059 40 Zr 91.224 41 Nb 92.9064 42 Mo 95.94 43 Tc (98) 44 Ru 101.07 45 Rh 102.906 46 Pd 106.42 47 Ag 107.868 48 Cd 112.411 49 In 114.818 50 Sn 118.710 51 Sb 121.75 52 Te 127.60 53 I 126.9045 54 Xe 131.30 6 55 Cs 132.905 56 Ba 137.327 57-71 * Rare Earths 72 Hf 178.49 73 Ta 180.948 74 W 183.85 75 Re 186.207 76 Os 190.23 77 Ir 192.22 78 Pt 195.09 79 Au 196.9665 80 Hg 200.59 81 Tl 204.37 82 Pb 207.2 82 Bi 208.9804 84 Po (209) 85 At (210) 86 Rn (222) 7 87 Fr (223) 88 Ra 226.025 89-103 ^ Actinides 104 Rf (261) 105 Ha (262) 106 Sg (263) 107 Ns (262) 108 Hs (265) 109 Mt (266) 110 (269) 111 (272) *Lanthanide Series 57 La 138.906 58 Ce 140.12 59 Pr 140.9077 60 Nd 144.24 61 Pm 145 62 Sm 150.4 63 Eu 151.96 64 Gd 157.25 65 Tb 158.9254 66 Dy 162.50 67 Ho 164.9304 68 Er 167.26 69 Tm 168.9342 70 Yb 173.04 71 Lu 174.967 ^Actinide Series 89 Ac 227.028 90 Th 232.0381 91 Pa 231.0359 92 U 238.029 93 Np 237.0482 94 Pu (244) 95 Am (243) 96 Cm (247) 97 Bk (247) 98 Cf (251) 99 Es (254) 100 Fm (257) 101 Md (258) 102 No 259 103 Lr 262
Strong Acids Strong Bases HCl, HBr, HI LiOH, NaOH, KOH HNO 3 Ca(OH) 2 (slightly soluble) HClO 4 Ba(OH) 2 H 2 SO 4 Sr(OH) 2
OXIDATION NUMBER RULES The oxidation number of a free element is always 0. The oxidation number of a monatomic ion equals the charge of the ion. The oxidation number of fluorine in compounds is -1. The oxidation number of hydrogen in compounds is +1. Exception: the oxidation number of hydrogen is -1 in metal hydrides, like CaH 2. The oxidation number of oxygen in compounds is -2. Exception: the oxidation number of oxygen is -1 in peroxides, like BaO 2. The oxidation number of Cl, Br, I in compounds is -1. Exception: when combined with O or F, the preceding rules apply. The oxidation numbers of all other elements in a compound adjust such that: The sum of the oxidation numbers of all of the atoms in a neutral compound is 0. The sum of the oxidation numbers in a polyatomic ion is equal to the charge of the ion. 3
Midterms Material 1. What is the correct value for V to the correct number of significant figures? V = (4/3)πr 3 π = 3.1412 r = 2.000 cm a. 3 10 2 cm 3 b. 3.3 10 1 cm 3 c. 33.50 cm 3 d. 33.51 cm 3 e. 33.506 cm 3 2. I drop an iron nail weighing 25 g into a beaker of oil with a density of 0.80 g/ml. The volume of the oil increases by 3.2 ml. What is the density of iron? a. 0.80 g/ml. b. 1.0 g/ml. c. 7.8 g/ml. d. 9.8 g/ml. e. 25 g/ml 3. Which of the following statements is CORRECT? a. The 13 C nucleus has 7 protons and 6 neutrons. b. The element with an isotope that has a mass number of 40 and equal numbers of protons and neutrons is Ca. c. A neutron has almost the same mass as a proton, but the opposite charge. d. An electron has the same charge as a proton. e. Hydrogen has only one isotope 1 H. 4. The charges on the monatomic ions of P, F, Rb and Al are: a. -3, -1, +1, +3 b. +3, +1, -1, -3 c. -2, -1, +2, +3 d. -1, -2, +1, +2 e. -3, -2, +2, +3 5. What is the correct name of the compound, FeSO 4? a. Iron (II) sulfite b. Iron sulfoxide c. Iron (III) sulfide d. Iron (III) sulfate e. Iron (II) sulfate 4
6. When the following equation is correctly balanced what is the ratio of moles of water produced to moles of oxygen (O 2 ) that are consumed? a. 4 / 5 b. 4 / 1 c. 2 / 4 d 3 / 5 e. 2 / 5 C 4 H 4 (g) + O 2 (g) CO 2 (g) + H 2 O(l) 7. How many grams of hydrogen are needed to reduce 10.0 g of tungsten oxide (WO 3, 231.8 g/mol) to tungsten metal? a. 0.261 g b. 0.0870 g c. 0.130 g d. 1.008 g e. 0.329 g WO 3 (s) + 3H 2 (g) W(s) + 3H 2 O(l) 8. If I dissolve 24.2 g of Fe(NO 3 ) 3 (molar mass = 241.9 g/mol) in 500 ml of water, what is the concentration of nitrate ions in the resulting solution? a. 0.200 M b. 0.100 M c. 0.600 M d. 0.300 M e. 0.500 M 9. Which of the following compounds will produce a precipitate when mixed with Ba(NO 3 ) 2 (aq) solution? a. 1 only b. 4 only c. 1 and 4 d. All of them e. None of them 1. NaOH(aq) 2. O 2 (g) 3. Pb(NO 3 ) 2 (aq) 4. HCl(aq) 5
10. Which of these statements is CORRECT? CH121 Summer 2009 Final a. Acids react with carbonates to make carbon dioxide. b. Oxidation is electron gain. c. A spectator ion is one that forms a precipitate. d. A base increases the concentration of protons in solution. e. Molarity is the number of moles of solute per liter of solvent. 11. Which species are oxidized/reduced in the following reaction? Mg(s) + 2HCl(g) MgCl 2 (aq) + H 2 (g) a. Mg and Cl in HCl are both reduced. b. Mg is oxidized and H in HCl is reduced. c. Cl in HCl is oxidized and H in HCl is reduced. d. H in HCl is oxidized and Mg is reduced. e. This is not a redox reaction. 12. Which of the following statements about a titration is INCORRECT? a. The equivalence point of an acid-base titration can be detected by the choice of the correct indicator. b. A volumetric flask contains an accurate volume of liquid. c. An acid-base titration can work if you add either base to acid, or acid to base. d. Titrations of the same volumes of 1 M HCl or 1 M H 2 SO 4 will both require the same volume of 1 M NaOH for neutralization. e. Titrations can be used for redox reactions as well as acid-base reactions. 13. I perform the following acid/base neutralization titration. HCl(aq) + NaOH(aq) -------> NaCl(aq) + H 2 O(l) 25.0 ml of hydrochloric acid solution of unknown concentration required 50.0 ml of 1.00 M sodium hydroxide solution to be neutralized. What is the concentration of the acid? a. 0.50 M b. 1.00 M c. 2.00 M d. 2.50 M e. 5.00 M 6
14. Which of the following statements is CORRECT? a. Energy is the capacity of a body to keep a constant temperature. b. Kinetic energy refers to the energy possessed by virtue of the position of a body in the gravitational field of the Earth. c. Potential energy can never be converted into kinetic energy. d. Energy can be created or destroyed in chemical reactions. e. The kinetic energy of molecules of ice is less than that of molecules of room temperature water. 15. I heat a 55.9 g piece of Fe (specific heat = 0.449 J / g K) heated to 250 C, then drop into a thermostatted water-bath maintained at 30 C. What is the value of the heat q transferred from the Fe to the water when the Fe has come to the temperature of the bath? a. +5.52 kj b. -5.52 kj c. 98.8 J d. -6.27 kj e. + 5.52 J 16. If a gas expands during a constant pressure chemical process during which heat flows out of the system, which of the following is statements is CORRECT? a. q is positive and w is negative b. q is negative and w is positive c. q is positive and w is zero d. q is negative and w is negative e. q is zero and w is positive 17. Which of the following statements is INCORRECT? a. The 1 st Law of Thermodynamics is: E = q + w. b. Enthalpy is the heat transfer at constant volume. c. When H is negative, the process is exothermic. d. During a phase change the temperature does not change. e. If the heat of vaporization is x J/g, then the heat change when 1 g of the substance condenses from the gas to liquid is x J/g. 7
18. Given the following reactions and enthalpy changes, C(s) + O 2 (g) ÿ CO 2 (g) CH 4 (g) + 2O 2 (g) ÿ CO 2 (g) + 2H 2 O(l) H 2 (g) + ½ O 2 (g) ÿ H 2 O(l) )H = -393.5 kj )H = -890.3 kj )H = -285.8 kj use Hess s Law calculate the enthalpy changes under standard conditions associated with the reaction a. - 998 kj b. + 74.8 kj c. -74.8 kj d. -211 kj e. +211 kj C(s) + 2H 2 (g) ÿ CH 4 (g) )H =? 19. Calculate the standard enthalpy of combustion of benzene (C 6 H 6 ) give the following data. C 6 H 6 (l) + 7.5O 2 (g) 6CO 2 (g) + 3H 2 O (l) given the following enthalpies of formation : H o f (kj/mol) C 6 H 6 (l) = +49.0 CO 2 (g) = -393.5 H 2 O (l) = -285.8 (HINT : why is the value for O 2 (g) missing?) a. -2696 kj b. -3512 kj c. -3267 kj d. -3169 kj e. -2897 kj 20. Arrange the following segments of the electromagnetic spectrum in order of increasing frequency. 1. AM radio 2. X-rays 3. Ultra-violet 4. Infra-red a. 1, 2, 3, 4 b. 4, 3, 2, 1 c. 1, 3, 4, 2 d. 1, 4, 3, 2 e. 3, 2, 1, 4 8
21. What is the energy contained in one photon from a UV laser that has a wavelength of 250 nm a. 7.95 10-28 J b. 6.63 10-34 J c. 7.95 10-19 J d. 250 J e. 7.95 10-19 kj 22. The diagram shows some transitions between energy levels in the H atom. Order the transitions by increasing wavelength. a. C, A, B b. B, C, A c. A, C, B d. C, B, A e. B, A, C A B C n = 4 n = 3 n = 2 n = 1 23. Which of the following represents an allowable set of quantum numbers? a. n = 2, l = -2, m l = 2 b. n = 3, l = 3, m l = -3 c. n = 1, l = 0, m l = -1 d. n = 2, l = 1, m l = -1 e. n = 0, l = 0, m l = 0 24. The principal quantum number (n) and the magnetic quantum number (m l ) determine respectively a. The size and orientation of an orbital. b. The orientation and shape of an orbital. c. The shape and size of an orbital. d. The size and shape of an orbital. e. The shape and orientation. 9
25. Select the correct list of orbital names for the following orbitals: a. s, d z2, p y b. d xy, s, p z. c. p y, s, d z2 d. p y, s, d x2-y2 e. s, d xz, p z 10