CHM 2046 Exam 1 Practice Test

CHM 2046 S24 Test 1 Review Questions PERIODIC TABLE OF THE ELEMENTS 1 IA 2 IIA 3 IIIB 4 IVB 5 VB 6 VIB 7 VIIB 8 ------ 9 VIIIB 10 ------ 11 IB 12 IIB 13 IIIA 14 IVA 15 VA 16 VIA 17 VIIA 18 VIIIA 1 H 1.008 2 He 4.003 3 Li 6.941 4 Be 9.012 5 B 10.81 6 C 12.01 7 N 14.01 8 O 16.00 9 F 19.00 10 Ne 20.18 11 Na 22.99 12 Mg 24.31 13 Al 26.98 14 Si 28.09 15 P 30.97 16 S 32.07 17 Cl 35.45 18 Ar 39.95 19 K 39.10 20 Ca 40.08 21 Sc 44.96 22 Ti 47.88 23 V 50.94 24 Cr 52.00 25 Mn 54.94 26 Fe 55.85 27 Co 58.93 28 Ni 58.69 29 Cu 63.55 30 Zn 65.39 31 Ga 69.72 32 Ge 72.61 33 As 74.92 34 Se 78.96 35 Br 79.90 36 Kr 83.80 37 Rb 85.47 38 Sr 87.62 39 Y 88.91 40 Zr 91.22 41 Nb 92.91 42 Mo 95.94 43 Tc (98) 44 Ru 101.1 45 Rh 102.9 46 Pd 106.4 47 Ag 107.9 48 Cd 112.4 49 In 114.8 50 Sn 118.7 51 Sb 121.8 52 Te 127.6 53 I 126.9 54 Xe 131.3 55 Cs 132.9 56 Ba 137.3 57 La 138.9 72 Hf 178.5 73 Ta 181.0 74 W 183.8 75 Re 186.2 76 Os 190.2 77 Ir 192.2 78 Pt 195.1 79 Au 197.0 80 Hg 200.6 81 Tl 204.4 82 Pb 207.2 83 Bi 209.0 84 Po (209) 85 At (210) 86 Rn (222) 87 Fr (223) 88 Ra 226.0 89 Ac 227.0 104 Rf (267) 105 Db (268) 106 Sg (271) 107 Bh (272) 108 Hs (277) 109 Mt (276) 110 Ds (281) 111 Rg (280) 112 Cn (285) 58 Ce 140.1 59 Pr 140.9 60 Nd 144.2 61 Pm (145) 62 Sm 150.4 63 Eu 152.0 64 Gd 157.3 65 Tb 158.9 66 Dy 162.5 67 Ho 164.9 68 Er 167.3 69 Tm 168.9 70 Yb 173.0 71 Lu 175.0 90 Th 232.0 91 Pa 231.0 92 U 238.0 93 Np (237) 94 Pu (244) 95 Am (243) 96 Cm (247) 97 Bk (247) 98 Cf (251) 99 Es (252) 100 Fm (257) 101 Md (258) 102 No (259) 103 Lr (260) Scoring :   Questions 1 through 20 are multiple choice and are worth 8 points each. 0 ] [ ] [ A kt A t    ln P 2 P 1 = − ΔΗ R ( 1 T 2 − 1 T 1 ) k t 2 ln 2 / 1  ∆T b = k b * i * m 0 ] ln[ ] ln[ A kt A t               1 2 1 2 1 1 * ln T T R E k k a   k A t 2 0 2 / 1  ∆ T f = k f * i * m 0 ] [ 1 ] [ 1 A kt A t   P solution  mol solvent mol solvent  i * mol solute P solvent 0   0 2 / 1 1 A k t  Constants: R = 0.08206 L-atm/mol-K R = 8.314 J/mol-K Conversions: 1 atm = 760 torr = 760 mm Hg Kelvin = Celsius + 273.15

CHM 2046 S24 Test 1 Review Questions Directions : Please use the following review questions as one resource in helping you prepare for the upcoming exam. It is recommended to take this as an actual exam, with a timer set to 65 minutes and no resources other than a calculator. Please keep in mind that your actual test will necessarily have different questions and will come from the learning objectives. Thus, your studying should focus on practicing all of the learning objectives and to not overly focus on the objectives seen here. 1. Which of the following aqueous solutions would have the highest value for boiling point? A. 0.20 m NaCl B. 0.10 m CaCl 2 C. 0.50 m CH 3 OH D. 0.30 m CaCl 2 E. 0.10 m CH 3 COCH 3 2. Which statements below are always true regarding the addition of a catalyst to a reaction: I. the catalyst is in the same state as the reactants II. the catalyst lowers the activation energy in a reaction III. the catalyst raises the value for the rate constant, k A. only I B. only II C. only III D. II and III E. All three statements 3. A reaction has a rate constant of 0.0185 s -1 and the only reactant has an initial concentration of 0.135 M. What is the concentration in molarity of this reactant after 125 seconds? A. 4.84 * 10 -5 B. 0.0134 C. 0.103 D. 0.310 E. 4.84 4. A chemical reaction in the form 2 A  3 B, is observed to have the rate of chemical A decrease at –0.15 mol/L-s. How would the rate of this reaction be reported in mol/L-s? A. 0.075 B. 0.10 C. 0.15 D. 0.23 E. 0.45 5. Provided the following experimental data, determine the correct rate law: Rate (mol / L-s) A (mol/L) B (mol/L) 2.87 * 10 -4 0.012 0.0207 7.16 * 10 -3 0.060 0.0621 2.87 * 10 -4 0.012 0.0621 A. Rate = 0.0238 [A] B. Rate = 1.15 [A] 2 C. Rate = 55.6 [A] D. Rate = 1.99 [A] 2 E. Rate = 0.667 [B] 2

CHM 2046 S24 Test 1 Review Questions 9. The salt MgCO 3 would dissociate into which ions and have what van’t Hoff factor? A. Mg 2+ and CO 3 2– with a van’t Hoff factor = 2 B. Mg + and CO 3 2– with a van’t Hoff factor = 3 C. Mg 2+ , C 4+ and O 2– with a van’t Hoff factor = 5 D. Mg + and CO 3 – with a van’t Hoff factor = 2 E. MgC 2+ and O 2– with a van’t Hoff factor = 4 10. Choose the substance with the highest viscosity. A. (CH 3 CH 2 ) 2 CO B. C 2 H 4 Cl 2 C. HOCH 2 CH 2 CH 2 CH 2 OH D. CF 4 E. C 6 H 14 11. List the following compounds in order of increasing vapor pressure. Cl 2 F 2 NH 2 CH 2 CH 3 A. NH 2 CH 2 CH 3 < Cl 2 < F 2 B. F 2 < NH 2 CH 2 CH 3 < Cl 2 C. NH 2 CH 2 CH 3 < F 2 < Cl 2 D. F 2 < Cl 2 < NH 2 CH 2 CH 3 E. Cl 2 < F 2 < NH 2 CH 2 CH 3 12. How many of the following would be associated with an increase in the rate of vaporization? i. An increase in temperature ii. An increase in the strength of intermolecular forces iii. An increase in the amount of surface area iv. An increase in vapor pressure A. none of the statements B. i and ii C. only iii D. i, iii and iv E. all four statements 13. The normal boiling point of the substance represented by the phase diagram on the right is approximately: A) 25 °C B) 50 °C C) 140 °C D) 270 °C E) 350 °C

CHM 2046 S24 Test 1 Review Questions 14. Place the following substances in order of increasing boiling point: CH 3 CH 2 OH Ar CH 3 OCH 3 A. Ar < CH 3 OCH 3 < CH 3 CH 2 OH B. CH 3 CH 2 OH < Ar < CH 3 OCH 3 C. CH 3 CH 2 OH < CH 3 OCH 3 < Ar D. CH 3 OCH 3 < Ar < CH 3 CH 2 OH E. Ar < CH 3 CH 2 OH < CH 3 OCH 3 15. Which term describes the energy change associated with overcoming the intermolecular forces among molecules so that molecules do not interact with each other? A. ΔH vap B. ΔH fus C. ΔH cond D. C p (gas) E. C p (liquid) 16. The vapor pressure of water is 92.5 torr at 50.0 Celsius. What is the vapor pressure (in torr) of a solution that has 35 grams of NaCl dissolved in 115 grams of water at this temperature? A. 7.94 B. 77.9 C. 84.6 D. 101 E. 110. 17. Given that the chemical reaction: S 8 ( g ) + 2 O 2 ( g )  4 S 2 O ( g ) is found to have a rate law of: Rate = k [S 8 ]. Which of the following actions would increase the rate of this reaction: I. Lowering temperature II. Increasing conc. of O 2 III. Increasing conc. of S 8 IV. Adding a catalyst A. None of them B. I and II C. III and IV D. II and III E. All of them 18. A solution is made by dissolving 40.0 grams of magnesium phosphate (MM = 262.87 g/mol) in 500 grams of water. The observed boiling point of the solution is 100.50°C, what is the observed Van’t Hoff factor for magnesium phosphate in this solution? The K b for water is 0.512°C/ m . A. 0.025 B. 1.6 C. 3.2 D. 4.8 E. 5.0 19. A reaction is found to have a rate constant of 12.5 s -1 at 25.0 Celsius. When you heat the reaction up by ten degrees Celsius, the rate of the reaction exactly doubles. What is the activation energy for this reaction in kJ/mol?

CHM 2046 S24 Test 1 Review Questions NH 3 + NH  N 2 + 2 H 2 ( slow ) PtH 2  H 2 + Pt 4. The normal boiling point for a substance is 63.0 °C and has a heat of vaporization value of 23.1 kJ/mol. Determine the boiling point in °C of the substance at 2.90 atm. A) 24.6 °C B) 64.6 °C C) 113 °C D) 273 °C E) 337 °C 5. Consider the phase diagram below for a specific compound, which of the following statement is TRUE describing the process from A to B ? A) The process is vaporization B) The process is freezing C) The process is fusion D) The process is deposition E) The process is sublimation 6. How many moles of CO 2 are needed to lower the vapor pressure of 20 moles of water from 80 torr to 78 torr? A) 0.51 mol B) 0.78 mol C) 0.98 mol D) 1.9 mol E) 20 mol 7. As the temperature of a reaction increases, which of the following is expected: Rate constant (k) Half-life (t 1/2 ) A) Increases Increases B) Decreases Increases C) Increases Decreases D) Decreases Decreases E) Increases Not predictable 8. Consider the compounds: CH 3 CH 2 OCH 2 CH 3 and CH 3 CH 2 CH 3 , determine the molecular polarity , and the strongest intermolecular

CHM 2046 S24 Test 1 Review Questions force present in each compound. CH 3 CH 2 OCH 2 CH 3 CH 3 CH 2 CH 3 A) Polar, H-bonding Nonpolar, H-bonding B) Polar, dipole-dipole Polar, dipole-dipole C) Nonpolar, London dispersion Nonpolar, dipole-dipole D) Polar, dipole-dipole Nonpolar, London dispersion E) Polar, H-bonding Nonpolar, London dispersion 9. What is the van’t Hoff factor for K 3 PO 4 ? A) 1 B) 2 C) 4 D) 5 E) 8 10. CHCl 3 has a boiling point of 61.2  C and a K b = 3.63  C/ m . What is the boiling point of a solution that has 0.5 moles of KBr added to 250 grams of CHCl 3 ? Assume complete dissociation of the KBr. A) 7.3  C B) 14.5  C C) 61.2  C D) 68.5  C E) 75.7  C 11. What are the effects on heat of vaporization (ΔH vap ) and rate of vaporization as the intermolecular force decreases? Heat of vaporization (ΔH vap ) Rate of vaporization A) Increase Decrease B) Increase Increase C) Decrease Decrease D) Decrease Increase E) Unchanged Decrease 12. Place the following substances in order of increasing vapor pressure at a given temperature. CH 3 OH CHF 3 CF 4 A) CH 3 OH < CHF 3 < CF 4 B) CH 3 OH < CF 4 < CHF 3 C) CF 4 < CH 3 OH < CHF 3 D) CF 4 < CHF 3 < CH 3 OH E) CHF 3 < CF 4 < CH 3 OH 13. As pressure decreases, what happens to the solubility of solids and gases in water?

CHM 2046 S24 Test 1 Review Questions molality ( m ) of the solution? The molar mass of Co(NO 3 ) 2 is 182.95 g/mol. A) 0.0018 m B) 0.0027 m C) 0.489 m D) 2.67 m E) 89.3 m 19. In an integrated rate law, the variable [A] t represents: A) the rate constant B) the concentration of product formed at time t C) the initial concentration of a reactant D) the concentration of a reactant at time t E) the amount of time that has passed 20. When a catalyst is added to a chemical reaction… A) intermediates will be removed, increasing the amount of products formed. B) the energy of the transition state will increase, increasing the rate of the reaction. C) intermediates will be removed, increasing the rate of the reaction. D) the activation energy will decrease, increasing the rate of the reaction. E) the activation energy will decrease, increasing the amount of products formed.