CHE 107 Fall 2017 Exam 1 Your Name: Your ID: Question #: 1 Fill in the blanks with the letter corresponding to the correct term. Use each term only once. Your response for each one should be a single letter. A = Dispersion B = Dipole-dipole C = Hydrogen bonding D = Ion-dipole 1 forces are present in mixtures of ionic compounds and polar compounds. 2 forces are only present between polar molecules. 3 forces are present between molecules containing hydrogen bonded directly to F, O, or N. 4 forces are present between all atoms and molecules due to temporary fluctuations in electron distribution. 1. 2. 3. 4. Question #: 2 Hydrides of Group 17 (in red) increase in boiling point from HCl to HI due to increasing 1 [dispersion, dipole-dipole, hydrogen bonding] forces. HF has a much higher boiling point than the other group 17 hydrides due to the presence of 2 [dispersion, dipoledipole, hydrogen bonding] forces.
1. 2. Question #: 3 Rank the following in order of strongest to weakest intermolecular forces by entering the letter corresponding to each structure: strongest 1 > 2 > 3 weakest 1. 2. 3.
Question #: 4 Which choice arranges the compounds in order of increasing (smallest to largest) boiling point? A. HCl <CH4 <He <HF B. He < HF < HCl < CH4 C. HCl < HF < CH4 < He D. He < CH4 < HCl < HF Question #: 5 Select the two true statements below: A. The rate of vaporization decreases as surface area increases. B. The rate of vaporization decreases as intermolecular forces increase. C. Hexane, C6H14, vaporizes faster than water, H2O. D. The rate of vaporization increases as temperature decreases. Question #: 6 A 25.0 ml sample of diethyl ether (C4H10O, 74.12 g/mol, density = 0.713 g/ml) is heated to the boiling point of 34.6 ºC. How much heat energy is required to completely vaporize the sample given that ΔHvap = 26.5 kj/mol at 34.6 ºC? A. 65.9 kj B. 9.27 kj C. 0.235 kj D. 6.37 kj
Question #: 7 Glacier National Park in Montana is approximately 4,100 ft above sea level with an atmospheric pressure of 681 torr. At what temperature does water (ΔHvap = 40.7 kj/mol) boil at Glacier National Park? A. 273 K B. 373 K C. 370. K D. 353 K Question #: 8 Which statement is false? A. Melting (fusion) is an exothermic process. B. Sublimation is an endothermic process. C. When a liquid is cooled to its freezing point, the temperature of the liquid remains constant while the substance freezes. D. The heat of fusion of a substance is generally smaller than its heat of vaporization. Question #: 9 How much energy is required to convert 12.9 g of solid acetone, C3H6O(s), at 94.7 o C to liquid acetone, C3H6O(l) at 56.3 o C? Molar Mass C3H6O Melting Point of C3H6O Boiling Point of C3H6O ΔHfus ΔHvap Cs of C3H6O(s) Cs of C3H6O(l) Cs of C3H6O(g) 58.1 g/mol 94.7 C 56.3 C 5.69 kj/mol 32.0 kj/mol 1.65 J/g C 2.17 J/g C 1.29 J/g C
A. 2.03 10 3 kj B. 5.49 kj C. 4.02 kj D. 21.9 kj Question #: 10 For the substance described by this phase diagram, what phase changes occur as the pressure is decreased from 100 atm to 0.010 atm at a temperature of 184 ºC? A. condensation followed by freezing B. sublimation followed by vaporization C. fusion (melting) followed by vaporization D. sublimation followed by condensation
Question #: 11 Europium (152 g/mol) crystallizes in a body-centered cubic unit cell with an edge length of 458 pm. What is the density of europium? A. 5.25 g/cm 3 B. 10.5 g/cm 3 C. 1.97 g/cm 3 D. 22.8 g/cm 3 Question #: 12 Lanthanum ions (large, white spheres) are located on all corners and in a body-centered position while oxide ions (small, gray spheres) are located on all of the edges of a cubic unit cell. The number of lanthanum ions in the unit cell is 1 and the number of oxide ions is 2. Use whole numbers as 1, 2, etc. for your answers and do not include units. 1. 2.
Question #: 13 Potassium iodide, KI, is a(n) 1 [molecular, ionic, network covalent] solid, which has a 2 [higher, lower] melting point than glucose, C6H12O6, which is a(n) 3 [molecular, ionic, network covalent] solid. 1. 2. 3. Question #: 14 Fill in the blanks with the following choices: insulator, semiconductor, conductor. Each choice will be used only once. Diagram A. represents a(n) 1 Diagram B. represents a(n) 2 Diagram C. represents a(n) 3 Only the material in diagram 4 [A, B, or C] can be doped to fine-tune its electrical properties. 1. 2. 3. 4.
Question #: 15 Which two of the following act as n-type semiconductors? A. silicon doped with gallium B. silicon doped with arsenic C. germanium doped with phosphorus D. germanium doped with indium Question #: 16 1 [Covalent, Ionic, Metallic] bonding gives rise to the properties of malleability, ductility, and conductivity of heat and electricity because electrons are 2 [localized, delocalized] between individual metal nuclei. 1. 2. Question #: 17 Which property of metals means they can be pounded into flat sheets? A. opaque B. ductile C. conductive D. malleable
Question #: 18 During solution formation, is most strongly affected by solute-solvent intermolecular forces. If is not too large and positive, entropy will overcome the energy gap, causing a solution to form. A. ΔHsolute; ΔHsolution B. ΔHsolvent; ΔHmix C. ΔHmix; ΔHsolution D. ΔH mix; ΔHsolvent Question #: 19 Under which two conditions will a solution always form? A. solvent-solute interactions >solvent-solvent and solute-solute interactions B. solvent-solute interactions <solvent-solvent and solute-solute interactions C. ΔHmix >ΔHsolute + ΔHsolvent and ΔHsolution is large and negative D. ΔHmix <ΔHsolute + ΔHsolvent and ΔHsolution is large and positive Question #: 20 Water (50.0 g) and solid KClO3 (20.0 g) are warmed from 30 C to 70 C with stirring. Describe the solution process.
A. A saturated solution of KClO 3 results at 70 C. B. A small amount of the KClO 3 dissolves, but most of it remains as a solid at 70 C. C. No KClO 3 dissolves at 70 C because ionic solutes are less water-soluble at higher temperatures. D. An unsaturated solution of KClO 3 results at 70 C. Question #: 21 1 [Increasing, Decreasing] temperature and 2 [increasing, decreasing] pressure increases the solubility of a gas. 1. 2.
Question #: 22 At 25 ºC and a partial pressure of 2.0 atm N 2, the concentration of nitrogen in water is 1.22 10 3 M. What is the solubility of nitrogen in water if the partial pressure is increased to 5.0 atm NH3 at 25 ºC? A. 1.60 10 3 M B. 2.44 10 3 M C. 4.82 10 3 M D. 3.05 10 3 M Question #: 23 What is the molarity of a 1.22 m sucrose (342 g/mol) solution with a density of 1.018 g/ml? A. 1.22 M B. 0.876 M C. 1.018 M D. 1.51 M Question #: 24 A solution at 25 ºC contains 2.0 mol of nonvolatile ethylene glycol and 18.0 mol of water. P (H2O) is 24 torr at 25 C. The vapor pressure of the solution is 1 torr. Report your answer with two significant figures. Do NOT include units in your answer. 1.
Question #: 25 What is the freezing point of an aqueous solution that boils at 109.50 o C? Kf(H2O) = 1.86 o C/m Kb(H2O) = 0.512 o C/m A. 0.00 o C B. 34.5 o C C. 9.50 o C D. 5.55 o C Question #: 26 An osmotic cell with a semipermeable membrane is set up with pure water on one side and a concentrated salt solution in the other. Which two statements can be made once the cell has achieved equilibrium, as shown below? A. The A side contains pure water. B. Water flowed from the pure water side to the concentrated salt side. C. Water flowed from the concentrated salt side to the pure water side. D. The A side contains the concentrated salt solution.
Question #: 27 Which two compounds have the indicated ideal van't Hoff factor? A. K2Cr2O7, i = 3 B. Li2SO4, i = 7 C. KMnO4, i = 2 D. NH4Cl, i = 6 Question #: 28 Which aqueous solution has the lowest boiling point? Assume ideal van t Hoff factors. A. 0.50 m KI B. 0.50 m (NH 4 ) 3 PO 4 C. 0.50 m sucrose (non-electrolyte) D. 0.50 m MgCl 2 Question #: 29 What is the freezing point of a solution containing 25.0 g of nickel(iii) chloride (NiCl3, 165 g/mol), dissolved in 0.125 kg of water? Kf(H2O) = 1.86 C/m 1 o C Report your answer with three significant figures. Do NOT include units in your answer. 1.
Question #: 30 A 2.07 g sample of a nonelectrolyte compound was dissolved in enough water to make 10.0 ml of solution at 20.0 C. The osmotic pressure of the resulting solution was 54.1 atm. What is the molar mass of the compound? A. 94.1 g/mol B. 92.0 g/mol C. 9.53 g/mol D. 8.27 g/mol
DRAFT Do Not Use Until Posted. CHE 107 Fall 2017 Exam 1 - Confidential Your Name: Your ID: attachment_for_pubexamuid_lnxp115059239850365083xx_217.jpg Question #: 1 Fill in the blanks with the letter corresponding to the correct term. Use each term only once. Your response for each one should be a single letter. A = Dispersion B = Dipole-dipole C = Hydrogen bonding D = Ion-dipole 1 forces are present in mixtures of ionic compounds and polar compounds. 2 forces are only present between polar molecules. 3 forces are present between molecules containing hydrogen bonded directly to F, O, or N. 4 forces are present between all atoms and molecules due to temporary fluctuations in electron distribution.
1. D 2. B 3. C 4. A Question #: 2 Hydrides of Group 17 (in red) increase in boiling point from HCl to HI due to increasing 1 [dispersion, dipole-dipole, hydrogen bonding] forces. HF has a much higher boiling point than the other group 17 hydrides due to the presence of 2 [dispersion, dipole-dipole, hydrogen bonding] forces. 1. dispersion 2. hydrogen bonding Question #: 3
Rank the following in order of strongest to weakest intermolecular forces by entering the letter corresponding to each structure: strongest 1 > 2 > 3 weakest 1. C; C. 2. A; A. 3. B; B. Question #: 4 Which choice arranges the compounds in order of increasing (smallest to largest) boiling point? A. HCl <CH 4 <He <HF B. He < HF < HCl < CH 4 C. HCl < HF < CH 4 < He D. He < CH 4 < HCl < HF Question #: 5 Select the two true statements below: A. The rate of vaporization decreases as surface area increases. B. The rate of vaporization decreases as intermolecular forces increase. C. Hexane, C 6 H 14, vaporizes faster than water, H 2 O. D. The rate of vaporization increases as temperature decreases.
Question #: 6 A 25.0 ml sample of diethyl ether (C 4 H 10 O, 74.12 g/mol, density = 0.713 g/ml) is heated to the boiling point of 34.6 ºC. How much heat energy is required to completely vaporize the sample given that ΔH vap = 26.5 kj/mol at 34.6 ºC? A. 65.9 kj B. 9.27 kj C. 0.235 kj D. 6.37 kj Question #: 7 Glacier National Park in Montana is approximately 4,100 ft above sea level with an atmospheric pressure of 681 torr. At what temperature does water (ΔH vap = 40.7 kj/mol) boil at Glacier National Park? A. 273 K B. 373 K C. 370. K D. 353 K Question #: 8 Which statement is false? A. Melting (fusion) is an exothermic process. B. Sublimation is an endothermic process. C. When a liquid is cooled to its freezing point, the temperature of the liquid remains constant while the substance freezes. D. The heat of fusion of a substance is generally smaller than its heat of vaporization. Question #: 9
How much energy is required to convert 12.9 g of solid acetone, C 3 H 6 O(s), at 94.7 o C to liquid acetone, C 3 H 6 O(l) at 56.3 o C? Molar Mass C 3 H 6 O Melting Point of C 3 H 6 O Boiling Point of C 3 H 6 O H fus H vap C s of C 3 H 6 O(s) C s of C 3 H 6 O(l) C s of C 3 H 6 O(g) 58.1 g/mol 94.7 C 56.3 C 5.69 kj/mol 32.0 kj/mol 1.65 J/g C 2.17 J/g C 1.29 J/g C A. 2.03 10 3 kj B. 5.49 kj C. 4.02 kj D. 21.9 kj Question #: 10 For the substance described by this phase diagram, what phase changes occur as the pressure is decreased from 100 atm to 0.010 atm at a temperature of 184 ºC?
A. condensation followed by freezing B. sublimation followed by vaporization C. fusion (melting) followed by vaporization D. sublimation followed by condensation Question #: 11 Europium (152 g/mol) crystallizes in a body-centered cubic unit cell with an edge length of 458 pm. What is the density of europium? A. 5.25 g/cm 3 B. 10.5 g/cm 3 C. 1.97 g/cm 3 D. 22.8 g/cm 3 Question #: 12 Lanthanum ions (large, white spheres) are located on all corners and in a body-centered position while oxide ions (small, gray spheres) are located on all of the edges of a cubic unit cell. The number of lanthanum ions in the unit cell is 1 and the number of oxide ions is 2. Use whole numbers as 1, 2, etc. for your answers and do not include units.
1. 2 2. 3 Question #: 13 Potassium iodide, KI, is a(n) 1 [molecular, ionic, network covalent] solid, which has a 2 [higher, lower] melting point than glucose, C 6 H 12 O 6, which is a(n) 3 [molecular, ionic, network covalent] solid. 1. ionic 2. higher 3. molecular Question #: 14
Fill in the blanks with the following choices: insulator, semiconductor, conductor. Each choice will be used only once. Diagram A. represents a(n) 1 Diagram B. represents a(n) 2 Diagram C. represents a(n) 3 Only the material in diagram 4 [A, B, or C] can be doped to fine-tune its electrical properties. 1. conductor 2. semiconductor 3. insulator 4. B Question #: 15 Which two of the following act as n-type semiconductors? A. silicon doped with gallium B. silicon doped with arsenic C. germanium doped with phosphorus D. germanium doped with indium Question #: 16 1 [Covalent, Ionic, Metallic] bonding gives rise to the properties of malleability, ductility, and conductivity of heat and electricity because electrons are 2 [localized, delocalized] between individual metal nuclei. 1. metallic metalic 2. delocalized Question #: 17 Which property of metals means they can be pounded into flat sheets? A. opaque
B. ductile C. conductive D. malleable Question #: 18 During solution formation, is most strongly affected by solute-solvent intermolecular forces. If is not too large and positive, entropy will overcome the energy gap, causing a solution to form. A. ΔH solute ; ΔH solution B. ΔH solvent ; ΔH mix C. ΔH mix ; ΔH solution D. ΔH mix ; ΔH solvent Question #: 19 Under which two conditions will a solution always form? A. solvent-solute interactions >solvent-solvent and solute-solute interactions B. solvent-solute interactions <solvent-solvent and solute-solute interactions C. ΔH mix >ΔH solute + ΔH solvent and ΔH solution is large and negative D. ΔH mix <ΔH solute + ΔH solvent and ΔH solution is large and positive Question #: 20 Water (50.0 g) and solid KClO 3 (20.0 g) are warmed from 30 C to 70 C with stirring. Describe the solution process.
A. A saturated solution of KClO 3 results at 70 C. B. A small amount of the KClO 3 dissolves, but most of it remains as a solid at 70 C. C. No KClO 3 dissolves at 70 C because ionic solutes are less water-soluble at higher temperatures. D. An unsaturated solution of KClO 3 results at 70 C. Question #: 21 1 [Increasing, Decreasing] temperature and 2 [increasing, decreasing] pressure increases the solubility of a gas. 1. decreasing 2. increasing Question #: 22 At 25 ºC and a partial pressure of 2.0 atm N 2, the concentration of nitrogen in water is 1.22 10 3 M. What is the solubility of nitrogen in water if the partial pressure is increased to 5.0 atm NH 3 at 25 ºC?
A. 1.60 10 3 M B. 2.44 10 3 M C. 4.82 10 3 M D. 3.05 10 3 M Question #: 23 What is the molarity of a 1.22 m sucrose (342 g/mol) solution with a density of 1.018 g/ml? A. 1.22 M B. 0.876 M C. 1.018 M D. 1.51 M Question #: 24 A solution at 25 ºC contains 2.0 mol of nonvolatile ethylene glycol and 18.0 mol of water. P (H 2 O) is 24 torr at 25 C. The vapor pressure of the solution is 1 torr. Report your answer with two significant figures. Do NOT include units in your answer. 1. 22 Question #: 25 What is the freezing point of an aqueous solution that boils at 109.50 o C? K f (H 2 O) = 1.86 o C/m K b (H 2 O) = 0.512 o C/m A. 0.00 o C B. 34.5 o C C. 9.50 o C D. 5.55 o C
Question #: 26 An osmotic cell with a semipermeable membrane is set up with pure water on one side and a concentrated salt solution in the other. Which two statements can be made once the cell has achieved equilibrium, as shown below? A. The A side contains pure water. B. Water flowed from the pure water side to the concentrated salt side. C. Water flowed from the concentrated salt side to the pure water side. D. The A side contains the concentrated salt solution. Question #: 27 Which two compounds have the indicated ideal van't Hoff factor? A. K 2 Cr 2 O 7, i = 3 B. Li 2 SO 4, i = 7 C. KMnO 4, i = 2 D. NH 4 Cl, i = 6
Question #: 28 Which aqueous solution has the lowest boiling point? Assume ideal van t Hoff factors. A. 0.50 m KI B. 0.50 m (NH 4 ) 3 PO 4 C. 0.50 m sucrose (non-electrolyte) D. 0.50 m MgCl 2 Question #: 29 What is the freezing point of a solution containing 25.0 g of nickel(iii) chloride (NiCl 3, 165 g/mol), dissolved in 0.125 kg of water? K f (H 2 O) = 1.86 C/m 1 o C Report your answer with three significant figures. Do NOT include units in your answer. 1. -9.02 Question #: 30 A 2.07 g sample of a nonelectrolyte compound was dissolved in enough water to make 10.0 ml of solution at 20.0 C. The osmotic pressure of the resulting solution was 54.1 atm. What is the molar mass of the compound? A. 94.1 g/mol B. 92.0 g/mol C. 9.53 g/mol D. 8.27 g/mol