Unformatted text preview: Exam One (questions 111) 1. Which compound is correctly named? A) HCl (aq) hydrogen chloride B) H2S sulfuric acid C) CoCl2 cobalt chloride D) VPO4 vanadium(III) phosphate E) NaClO sodium chlorite 2. A radio wave has a frequency of 3.8 x 1010 s‐1. How many photons of this radiation are needed to produce 60.7 J of energy? A) 2.52 x 10‐23 photons B) 2.41 x 1024 photons C) 1.74 x 10‐44 photons D) 1.88 x 1017 photons E) Not enough information 3. Rank the emissions in terms of increasing energy: I. n = 5 n = 4 II. n = 3 n = 2 III. n = 2 n = 1 A) I < II < III B) III < II < I C) II < I < III D) III < I < II E) The energies of emissions I, II, and III are all the same 4. Which statement is false? A) The principle quantum number indicates the energy level and size of an orbital. B) The only allowed values for the spin quantum number are +½ and – ½. C) The values for the magnetic quantum number indicate the orientation of the orbitals in space. D) The value l = 2 indicates a peanut shaped orbital. E) With an increase in energy level, a new type of orbital becomes available. Form A Page 1 5. How many orbitals in an atom can have the designation 5f? A) 5 B) 7 C) 14 D) 25 E) 50 6. Which statement is true? A) A 1.0 L sample of 0.200 M Ca(OH)2 contains 1.20 x 1023 hydroxide ions. B) In a dilution, the volume of solution remains constant while the moles of solute decreases. C) There are 124 moles of solute in 145.6 mL of 0.850 M sodium cyanide. D) To prepare 0.80 L of 0.15 M NaCl, 0.020L of 5.0 M NaCl must be diluted to a total volume of 800. mL. E) It takes 21.1 g of KI to make 500.0 mL of 0.254 M KI solution. 7. Boron has two isotopes; one of these is boron‐10 with a mass of 10.0129 amu and a percent abundance of 19.91%. If the universal mass of boron is 10.811, what is the mass of the other isotope of boron. A) 11.01 amu B) 44.29 amu C) 14.02 amu D) 10.90 amu E) There is not enough information to answer this question. 8. All of the substances below are fertilizers. Which is the richest source of nitrogen on a mass percentage basis? A) Urea, (NH2)2CO B) Ammonium nitrate, NH4NO3 C) Guanidine, HNC(NH2)2 D) Ammonia, NH3 E) There is not enough information to answer this question Form A Page 2 9. Depicted below is a reaction vessel containing a mixture of H2(g) and N2(g) before the reaction begins. The filled spheres represent nitrogen and the open spheres represent hydrogen. Given the equation below, which image best represents the vessel after reaction occurs? N2(g) + 3H2(g) 2NH3(g) Form A Page 3 10. How many moles of carbon monoxide are required to react with one mole of O2(g) to produce 2 moles of carbon dioxide gas? A) ½ B) 1 C) 2 D) 3/2 E) 3 11. What are the spectator ions in the reaction of sulfuric acid with barium hydroxide? A) Ba2+ and SO42‐ B) H+ and OH‐ C) OH‐ and Ba2+ D) H+ and SO4 2‐ E) There are no spectator ions in this reaction. Exam Two (questions 1221) 12. Which statement best explains why the following ionic radii trend is true? S2‐ > Cl ‐ > K+ A) Zeff increases with the number of electrons. B) The potassium ion has the least amount of shielding, so Zeff is greatest for it. C) Zeff increases with the number of protons. D) The amount of shielding is equal, but the nucleus of sulfur is least positive resulting in smallest Zeff. E) The radii trend above is not correct. 13. Which periodic trend refers to the ability of an atom in a molecule to attract electrons to itself? A) electron affinity B) ionization energy C) polarizability D) polarizing power E) electronegativity Form A Page 4 14. Which transition metal ion has the electron configuration [Ar]3d3? A) V3+ B) Mn4+ C) Cr3+ D) Fe3+ E) Ti2+ 15. Which is the best resonance structure for the sulfate ion? 16. Which molecule is trigonal pyramidal? A) SO2 B) AsBr3 C) BrF3 D) BH3 E) CH2O 17. Which molecule or ion is polar? A) XeF4 B) PCl3 C) CCl4 D) I3 – E) BH3 Form A Page 5 18. Arrange the following in order of increasing net dipole (dipole moment). A) I < II < III B) III < I < II C) II < III < I D) II < I < III E) I < III < II 19. Which best explains the polarity of a bond? A) Lewis theory B) VSEPR C) Valence bond theory D) Electronegativity E) Electron affinity 20. Which statement regarding the following Lewis structure is true? A) The structure has too many electrons B) The structure has no resonance structures. C) The formal charge distribution prevents it from contributing significantly to the resonance hybrid. D) The structure is wrong because boron cannot have a complete octet. E) The structure is missing an overall charge. Form A Page 6 21. What atomic orbitals are involved in the pi bond found in O2? A) two s orbitals B) an s orbital and a p orbitals oriented along the internuclear axis C) two p orbitals oriented along the internuclear axis D) an s orbital and a p orbital that is perpendicular to the internuclear axis. E) two p orbitals that are perpendicular to the internuclear axis Exam Three (questions 22—31) 22. How many and what type of atomic orbitals must be combined to account for the tetrahedral shape of CH4? A) 2 s orbitals B) 4 p orbitals C) 8 p orbitals D) 1 s and 3 p orbitals E) 2 s and 6 p orbitals 23. Which of the following species has a longer bond length and why? N2 or N2+ A) N2 has a longer bond because its bond order is smaller B) N2 has a longer bond because its bond order is greater C) Both species have the same bond length D) N2+ has a longer bond because its bond order is smaller E) N2+ has a longer bond because its bond order is greater 24. What is the molecular orbital electron configuration for F2 ‐ ? A) (σ2s) 2( σ2s*)2(σ2p)2(π2p)4(π2p*)4(σ2p*)1 B) (σ2s) 2( σ2s*)2(σ2p)2(π2p)4(π2p*)3 C) (σ2s) 2( σ2s*)2(σ2p)2(π2p)4(π2p*)4 D) (σ2s) 2( σ2s*)2(π2p)4(σ2p)2(π2p*)4(σ2p*)1 E) (σ2s) 2( σ2s*)2(π2p)4(σ2p)2(π2p*)3 Form A Page 7 25. The volume of a sample of ideal gas is 24.8 mL at 1.12 atm. If the pressure of the sample is increased, at constant temperature, to 2.64 atm, then what is the new volume of the sample in liters? A) 10.5 L B) 0.119 L C) 0.0566 L D) 0.0105 L E) 0.00660 L 26. If it takes 1.25 min for 0.010 mol of He to effuse, how long will it take for the same amount of C2H6 to effuse under the same conditions? A) 3.43 min B) 2.19 min C) 0.456min D) 2.74 min E) 0.0228 min 27. What mass of potassium chloride forms when 5.25 L of chlorine gas at 0.950 atm and 293 K reacts with 17.0 g of potassium? A) 30.9 g KCl B) 32.4 g KCl C) 681 g KCl D) 15.4 g KCl E) 341 g KCl 28. How many atoms are in one unit cell of the structure below? A) 1 B) 2 C) 3 D) 4 E) 9 Form A Page 8 29. Which substance would you expect to have the lowest boiling point? A) CH4 B) SiH4 C) CH3Cl D) SiH2Cl2 E) CH3F 30. If a unit cell of an ionic compound has A cations at the corners and the face centers and X anions in the centers of the unit cells of the edges, what is the empirical formula of the compound? A) A4X3 B) A6X3 C) A4X2 D) A3X4 E) A3X3 31. An element crystallizes in a face‐centered cubic unit cell has a density of 1.45 g/cm3. The edge length of its unit cell is 4.52 x 10‐8 cm. What is the approximate atomic mass of the element in g/mol? A) 3.35 g/mol B) 9.87 g/mol C) 20.2 g/mol D) 80.7 g/mol E) Not enough information Section IV (questions 3241) 32. If expanding gases in a car engine do 451 J of work on the pistons, and the system loses 325 J to the surroundings as heat, calculate the change in internal energy (ΔU) in J. A)+136 J B) ‐776 J C) ‐96 J D) ‐126 J E) +802 J Form A Page 9 33. A layer of copper lining a skillet weighs 125 g. What is the specific heat capacity of the copper if 13.3 kJ heat is needed to raise the temperature of the copper from 25oC to 300.oC ? A) 9.40 J/goC B) 2.56 J/goC C) 0.387 J/goC D) 0.000387 J/goC E) 29.26 J/goC 34. For which species is the enthalpy of formation NOT zero? A) Na(s) B) Cl2(g) C) N2(g) D) H2O(g) E) None of the above 35. Consider two metals A and B. The specific heat capacity of A has a greater value than that of B. Which statement is true? A) More heat is required to raise the same mass of metal B by 1oC than metal A. B) Given the same amount of heat energy and the same mass of both metals, the temperature of A will rise more than the temperature of B. C) If the same mass of both metals, beginning at the same initial temperature, are each placed on a table, then metal B will reach room temperature faster. D) If the metals, both at different temperatures, are placed in contact with each other, metal A will exhibit a greater temperature change than metal B. E) None of these statements are true. 36. What is the change in entropy of the surroundings for the following process at 25oC? N2(g) + 3H2(g) 2NH3(g) ΔHo = ‐92.6 kJ/mol A) +311 J/K B) ‐311 J/K C) +3220 J/K D) ‐371 J/K E) ‐27.4 J/K Form A Page 10 37. A 100.0 mL sample of 0.500 M HCl was mixed with 100.0 mL of 0.500 MNaOH in a coffee‐cup calorimeter. The initial temperature of both solutions was room temperature, 22.50oC and the final temperature of the mixture was 25.86oC. If no heat is lost to the surroundings or the calorimeter, then what is the enthalpy of reaction? The specific heat capacity of water is 4.184 J/g•°C., and the density of the solution is 1.00 g/mL. A) ‐2.81 kJ/mol B) +56.2 kJ/mol C) +2. 81 kJ/mol D) ‐5.62 kJ/mol E) ‐56.2 kJ/mol 38. In question 36, you were told to assume that no heat was lost to the surroundings or calorimeter. What can you assume about the value of ΔH if Ccal were greater than 0? A) The value of ΔH is not affected by a non‐zero Ccal. B) The value of ΔH becomes zero. C) The real absolute value of ΔH would be greater than calculated in question 36. D) The real absolute value ΔH would be less than calculated in question 36. E) Without the value of Ccal, there is not enough information. 39. Determine the standard enthalpy of formation for C2H2 from its elements given the information below. 2C(graphite) + H2(g) C2H2(g) ΔHo = ? Given: C(graphite) + O2(g) CO2(g) ΔHo = ‐383.5 kJ/mol H2(g) + ½ O2(g) H2O(l) ΔHo = ‐285.8 kJ/mol 2C2H2(g) + 5 O2(g) 4CO2(g) + 2H2O(l) ΔHo = ‐2598.8 kJ/mol A) +226.6 kJ/mol B) +246.6 kJ/mol C) +1930 kJ/mol D) ‐3650 kJ/mol E) ‐1830 kJ/mol Form A Page 11 40. Which processes lead to an increase in entropy? Treat all gases as ideal. I. The pressure of 1 mole of oxygen gas is allowed to double isothermally. II. Carbon dioxide is allowed to expand isothermally to 10 times its original volume. III. The temperature of 1 mol of helium is increased by 25oC at constant pressure. IV. Nitrogen gas is compressed isothermally to half its original volume. A) I and IV B) I only C) III and IV D) II and III E) I and II 41. Which statement regarding the graph is true? %" &"
!" A) Regions A, C, and E represent phase changes. B) No heat is exchanged in regions B and D. C) ΔHvap is much larger than ΔHfus for this substance. D) The freezing point of the substance is ‐25oC. E) None of these statements are true. Form A Page 12 Section V (questions 42—53) 42. Calculate the molar heat of fusion for benzene given the following data: ΔSfus = 39.1 J/mol•K ΔSvap = 87.8 J/mol•K ΔHvap = 33.9 kJ/mol Normal melting point = 5.5oC Normal boiling point = 80.1oC A) 31.0 kJ/mol B) 7.11 kJ/mol C) 140. kJ/mol D) 10.9 kJ/mol E) 215 kJ/mol 43. Use the information from question 42 to determine the Gibbs free energy for the evaporation of benzene. A) 0 kJ/mol B) 2.90 kJ/mol C) 3.10 x 104 kJ/mol D) 64.9 kJ/mol E) Not enough information 44. For which of these processes is ΔS positive? I. Ag+(aq) + Cl – (aq) AgCl(s) II. sublimation III. 2O3(g) 3O2(g) IV. condensation A) I and IV B) II and III C) II and IV D) II only E) III and IV Form A Page 13 45. Which statement best explains why water freezes only at or below 0oC at atmospheric pressure. A) Freezing is an endothermic process with an increase in entropy. B) Freezing is an exothermic process with decrease in entropy. C) The sign of ΔG for the process is always positive. D) Freezing is an endothermic process with a decrease in entropy. E) Freezing is an exothermic process with an increase in entropy. 46. The density of a 2.45 M aqueous solution of methanol (CH3OH, molar mas = 32.04 g/mol) is 0.976 g/mL. What is the molality of the solution? A) 2.45 m B) 0.0314 m C) 3.18 m D) 2.51 m E) 2.73 m 47. By how much does the vapor pressure change when 218 g of glucose (non‐
volatile solute, molar mass = 180.2 g/mol) is dissolved in 460.0 mL of water at 300C. At this temperature, the vapor pressure of pure water is 31.82 torr, and the density of water is 1.00 g/mL. A) The vapor pressure decreases by 1.4 torr B) The vapor pressure increases by 1.4 torr C) The vapor pressure decreases by 30.4 torr D) The vapor pressure increases by 30.04 torr E) The vapor pressure does not change. 48. Which statement is true? A) CH3OH has a higher vapor pressure than CH4 at a given temperature. B) Boiling points tend to decrease with increasing strength of intermolecular forces. C) Boiling point and melting point follow opposite trends with respect to intermolecular forces. D) The easier it is for molecules to escape the liquid phase to the gas phase, the greater the vapor pressure will be. E) H2O has a lower boiling point than CH4. Form A Page 14 49. Molecule A has i = 1 while molecule B has i =2. The molality of an aqueous solution of molecule A is exactly half that of molecule B. Which statement is true? A) The solution of molecule B will result in a higher freezing point. B) The solution of molecule A will result in a lower vapor pressure. C) The osmotic pressure of solution A is greater than that of B. D) The two solutions have the same boiling point. E) The boiling point, freezing point, osmotic pressure, and vapor pressure cannot be calculated without knowing the identities of the molecules. 50. A solution is prepared by dissolving 35.0 g of hemoglobin (Hb) in enough water to make 1.00L of solution. If the osmotic pressure of the solution is 0.0132 atm at 25oC, then what is the molar mass of hemoglobin? A) 108 g/mol B) 65100 g/mol C) 2270000 g/mol D) 0.00926 g/mol E) 1.54 x 10‐5 g/mol 51. The freezing point depression of an aqueous 0.100 m solution of MgSO4 is 0.225oC. What is the van't Hoff factor? The Kf for water is 1.86oC/m. A) 1 B) 2 C) 6 D) 1.2 E) Not enough information 52. For a given solution, which of the following concentration values will change as temperature changes? A) mass percent B) molarity C) mole fraction D) molality E) none of these choices is correct Form A Page 15 53. Consider the following reaction: A + B → C + D ΔGrxn= ‐200 kJ Based on this information, which of the following statements can be made about the reaction? I. The reaction is spontaneous. II. The products are more stable than the reactants. III. The reaction is exothermic. IV. The reactants are labile. A) I only B) III only C) I and II only D) I, II, and IV only E) I, II, III, and IV 54. Which form of the exam do you have? A) B) Form A Page 16 ...
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- Fall '09
- pH, Vapor pressure, Zeff, Ccal