A) sublimation. B) liquefaction. C) evaporation. D) condensation. E) freezing. 11. Below is a phase diagram for a substance.

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1 PX Which of the following statements concerning liquids is incorrect? A) The volume of a liquid changes very little with pressure. B) Liquids are relatively incompressible. C) Liquid molecules move slowly compared to solids. D) Non-volatile liquids have low vapor pressures at room temperature. E) The molecules of a liquid are in constant random motion. 2. What is the name for the following phase change? I 2 (s) I 2 (g) A) sublimation B) freezing C) vaporization D) condensation E) melting 3. Enough of a volatile liquid is placed in a closed container to achieve a liquid-vapor equilibrium. Which of the following statements regarding this system is/are correct once equilibrium is established? 1. The rate of condensation is equal to the rate of evaporation. 2. The fraction of molecules with enough energy to escape the liquid surface depends on the liquid surface area. 3. The vapor pressure is independent of the temperature. A) 1 only B) 2 only C) 3 only D) 1 and 2 E) 1, 2, and 3 4. The boiling point of a liquid is A) always the temperature at which the vapor pressure equals 760 mmhg (1 atm). B) always the temperature at which the liquid phase of a substance is in equilibrium with the vapor phase. C) always the temperature at which the vapor pressure equals the pressure exerted on the liquid. D) always equal to the vapor pressure of the liquid at a given temperature. E) independent of the pressure exerted on the liquid. 5. The enthalpy of fusion of sodium is 2.60 kj/mol. How many grams of sodium can be melted by adding 81.7 kj of energy to the metal at its melting point? A) g B) 9.24 g C) 3.55 g D) 31.4 g

E) 1.50 10 3 g 6. How much heat is released at constant pressure if a 14.0-L tank containing 56.0 atm of hydrogen sulfide gas condenses at its boiling point of -60.0 o C?

2 E) g 6. How much heat is released at constant pressure if a 14.0-L tank containing 56.0 atm of hydrogen sulfide gas condenses at its boiling point of o C? The enthalpy of vaporization of hydrogen sulfide is 18.7 kj/mol at o C. (R = L atm/(k mol)) A) J B) J C) J D) J E) J 7. The vapor pressure of a given liquid will increase if A) the liquid is moved to a container in which its surface is very much larger. B) the volume of the liquid is increased. C) the temperature is increased. D) the volume of the vapor phase is increased. E) a more volatile liquid is added to the given liquid. 8. A particular compound has an enthalpy of vaporization of J/mol. At 281 K it has a vapor pressure of 101 mmhg. What is its vapor pressure at 301 K? (R = 8.31 J/(K mol)) A) 98.8 mmhg B) 123 mmhg C) 45.2 mmhg D) 226 mmhg E) 103 mmhg 9. In the accompanying phase diagram, a liquid can be present at combinations of temperature and pressure corresponding to points A) A, C, G, and D. B) A, C, D, and F. C) A, B, C, and G. D) A and C only. E) G, C, D, and E. 10. From a consideration of the phase diagram below, a change from point M to point N corresponds to

3 A) sublimation. B) liquefaction. C) evaporation. D) condensation. E) freezing. 11. Below is a phase diagram for a substance. Which line represents the melting-point curve of the substance? A) R-X B) S-X C) X-Z D) S-Z E) M-N 12. Which of the following forces is/are responsible for capillary action, a property of liquids? A) 1 B) 2 C) 3 1. attractive forces between the liquid and the capillary material 2. surface tension of the liquid 3. viscosity of the liquid

4 D) 1 and 2 E) 1, 2, and The measure of the resistance to flow of a liquid is A) London forces. B) van der Waals forces. C) viscosity. D) vapor pressure. E) surface tension. 14. Which of the following compounds has the highest vapor pressure at 25 C? A) CH 3 CH 2 OH B) CH 3 CH 2 CH 2 CH 3 C) CH 3 OCH 3 D) CH 3 CH 2 CH 3 E) CH 3 CH 2 CH 2 Cl 15. Which of the following pure substances has the lowest normal boiling point? A) H 2 S B) NH 3 C) H 2 O D) H 2 Te E) H 2 Se 16. Which of the following indicates the existence of strong intermolecular forces of attraction in a liquid? A) a very low critical temperature B) a very low boiling point C) a very low vapor pressure D) a very low viscosity E) a very low enthalpy of vaporization 17. Which of the following compounds is expected to have the lowest vapor pressure? A) CH 3 OCH 3 B) CH 3 CH 2 F C) CH 3 CH 2 OH D) CH 3 CH 2 CH 2 CH 3 E) CH 3 CH 2 CH Which of the following pure substances has the lowest vapor pressure at 25 C? A) SbH 3 B) NH 3 C) PH 3 D) AsH 3 E) H 2 O 19. Rank the following molecules in order of increasing normal boiling point: CH 3 CH 2 OH, CH 3 CH 2 CH 2 OH, CH 3 CH 2 OCH 3. A) lowest CH 3 CH 2 CH 2 OH, CH 3 CH 2 OCH 3, CH 3 CH 2 OH highest.

5 B) lowest CH 3 CH 2 OH, CH 3 CH 2 OCH 3, CH 3 CH 2 CH 2 OH highest. C) lowest CH 3 CH 2 CH 2 OH, CH 3 CH 2 OH, CH 3 CH 2 OCH 3 highest. D) lowest CH 3 CH 2 OCH 3, CH 3 CH 2 OH, CH 3 CH 2 CH 2 OH highest. E) lowest CH 3 CH 2 OCH 3, CH 3 CH 2 CH 2 OH, CH 3 CH 2 OH highest. 20. When two water molecule form a hydrogen bond, which atoms are involved in the interaction? A) Two hydrogens from one molecule and one hydrogen from the other molecule B) An oxygen from one molecule and an oxygen from the other molecule C) Two hydrogens from one molecule and one oxygen from the other molecule D) A hydrogen from one molecule and a hydrogen from the other molecule E) A hydrogen from one molecule and an oxygen from the other molecule 21. Which of the following pure substances may exhibit hydrogen bonding? A) CH 3 Cl B) CH 3 OCH 3 C) H 2 CO D) N(CH 3 ) 3 E) H 2 NNH The strongest intermolecular forces between molecules of PH 3 are A) hydrogen bonds. B) covalent bonds. C) ionic bonds. D) London forces. E) dipole dipole attractions. 23. Which of the following concerning solutions is/are correct? 1. The solvent in a mixture of gases is generally considered to be the substance in greater amount. 2. The solid dissolved in a solution is known as the solute. 3. Solid solutions are called alloys. A) 1 only B) 2 only C) 3 only D) 1 and 2 E) 1, 2, and Which of the following concerning solubility and the solution process is/are correct? 1. Both hydration energies and lattice energies depend on the magnitude of the ion charges and the size of the ions. 2. An initially nonhomogeneous mixture of two miscible liquids, given enough time, will eventually form a solution as a result of random molecular motions. 3. The dissolution of ionic compounds in water depends only on the hydration energy of the ions. A) 1 only

6 B) 2 only C) 3 only D) 1 and 2 E) 1, 2, and Which of the following pure liquids is the best solvent for sodium fluoride? A) CCl 4 (l) B) C 2 Cl 6 (l) C) HCl(l) D) BCl 3 (l) E) PCl 5 (l) 26. Which of the following correctly states the relationship between the solubility of a substance in water and temperature? A) The solubility of a substance in water increases as the temperature rises, especially for gases. B) The solubility of a substance in water decreases as the temperature lowers, especially for gases. C) The relationship between the solubility of a substance in water and temperature cannot be accurately predicted, especially for ionic solids. D) The solubility of a substance in water decreases as the temperature rises, especially for ionic solids. E) Two of these are correct. 27. Consider the following gas-aqueous liquid equilibrium for a closed system at a constant temperature. O 2 (g) O 2 (aq) What is the effect on the equilibrium composition of the liquid when the partial pressure of O 2 gas above the liquid is increased? A) The amount of O 2 dissolved in the liquid increases. B) The amount of O 2 dissolved in the liquid decreases. C) The amount of O 2 dissolved in the liquid does not change. D) Not enough information is provided to answer the question. E) Either A or B. 28. How does the solubility of a gas in a solvent depend on pressure and temperature? A) Increasing the partial pressure of the gas while increasing the temperature increases the solubility of the gas. B) Decreasing the partial pressure of the gas while decreasing the temperature increases the solubility of the gas. C) Increasing the partial pressure of the gas while decreasing the temperature increases the solubility of the gas. D) Decreasing the partial pressure of the gas while increasing the temperature increases the solubility of the gas. E) Gas solubility is unaffected by pressure or temperature.

7 29. At a particular temperature the solubility of O 2 in water is g/l at an oxygen pressure of around 14.7 atm. What is the Henry's law constant for O 2 (in units of L atm/mol)? A) B) C) D) E) None of the above are within 5% of the correct answer. 30. If the solubility of O 2 at bar and 25 C is 15.0 g/100 g H 2 O, what is the solubility of O 2 at a pressure of 1.72 bar and 25 C? A) 71.7 g/100 g H 2 O B) 24.2 g/100 g H 2 O C) g/100 g H 2 O D) g/100 g H 2 O E) 3.14 g/100 g H 2 O 31. Which of the following is not a colligative property? A) boiling-point elevation B) osmotic pressure C) gas solubility D) freezing-point lowering E) vapor-pressure lowering 32. As the number of solute particles in a given volume of solution increases, A) the boiling point will increase and the vapor pressure will increase. B) the freezing point will decrease and the vapor pressure will decrease. C) the freezing point will increase and the vapor pressure will increase. D) the boiling point will decrease and the vapor pressure will decrease. E) the osmotic pressure will decrease and the lattice energy will increase. 33. The molarity of a solution is defined as the A) moles of solute per liter of solvent. B) grams of solute per kilogram of solvent. C) grams of solute per liter of solution. D) moles of solute per liter of solution. E) moles of solute per kilogram of solvent. 34. The molarity of a solution is defined as the A) moles of solute per liter of solvent. B) moles of solute per kilogram of solution. C) moles of solute per mole of solution. D) moles of solute per kilogram of solvent. E) moles of solute per liter of solution. 35. What mass of an aqueous 22.9% sodium chloride solution contains 99.5 g of water? A) 129 g B) 29.6 g C) g

8 D) 22.8 g E) 99.5 g 36. The volume of a 14.4% (by mass) solution is 67.0 ml. The density of the solution is g/ml. What is the mass of the solution? A) 71.8 g B) 62.5 g C) 1030 g D) 103 g E) 10.3 g 37. What is the molarity of a 20.0% by mass hydrochloric acid solution? The density of the solution is g/ml. A) 6.86 M B) M C) 5.68 M D) 6.02 M E) M 38. How many moles of urea (60. g/mol) must be dissolved in 77.6 g of water to give a 3.5 m solution? A) mol B) 3.5 mol C) mol D) 0.27 mol E) mol 39. What is the molality of a solution that contains 77.7 g of 1,4-dichlorobenzene (C 6 H 4 Cl 2 ) in 445 ml of carbon tetrachloride (CCl 4 )? The density of CCl 4 is 1.60 g/ml. A) m B) m C) m D) m E) 1.90 m 40. What is the mole fraction of urea, CH 4 N 2 O, in an aqueous solution that is 36% urea by mass? A) 0.14 B) 0.86 C) 0.36 D) 0.55 E) What is the mole fraction of water in a water ethanol solution that is 46.0% water by mass? (Ethanol is C 2 H 5 OH.) A) 0.28 B) 0.31 C) 0.25 D) 0.69 E) 0.54

9 42. What is the vapor pressure at 20 C of an ideal solution prepared by the addition of 8.87 g of the nonvolatile solute urea, CO(NH 2 ) 2, to 57.6 g of methanol, CH 3 OH? The vapor pressure of pure methanol at 20 C is 89.0 mmhg. A) 6.75 mmhg B) 69.1 mmhg C) 77.1 mmhg D) 82.2 mmhg E) 19.9 mmhg 43. The fact that the boiling point of a pure solvent is lower than the boiling point of a solution of the same solvent is a direct consequence of the A) freezing-point depression of the solution. B) vapor pressure of the solution being higher than the vapor pressure of the pure solvent. C) osmotic pressure of the solvent being lower than the osmotic pressure of the solution. D) vapor pressure of the solution being lower than the vapor pressure of the pure solvent. E) osmotic pressure of the solvent being higher than the osmotic pressure of the solution. 44. What is the freezing point of a 0.24 m solution of glucose, C 6 H 12 O 6, in water? (K f for water is C/m.) A) 0.22 C B) 0.45 C C) 0.45 C D) 0.22 C E) 0.89 C 45. When a 28.4-g sample of an unknown compound is dissolved in 500. g of benzene, the freezing point of the resulting solution is 3.77 C. The freezing point of pure benzene is 5.48 C, and K f for benzene is 5.12 C/m. Calculate the molar mass of the unknown compound. A) 145 g/mol B) 170. g/mol C) 85.0 g/mol D) 340 g/mol E) 16.6 g/mol 46. What is the molar mass of an aromatic hydrocarbon if 0.85 g of the compound depresses the freezing point of 128 g of benzene by 0.37 C? (K f for benzene is 5.12 C/m.) A) 35 g/mol B) 150 g/mol C) 93 g/mol 92 D) 2100 g/mol E) 140 g/mol 47. Determine the osmotic pressure of a solution that contains g of a hydrocarbon solute (molar mass = 340 g/mol) dissolved in benzene to make a 350-mL solution. The temperature is 20.0 C.

10 A) 0.9 torr B) 2.0 torr C) 0.14 torr D) 0.7 torr E) 2.1 torr 48. Osmotic pressure is A) inversely proportional to mass fraction. B) directly proportional to lattice energy. C) inversely proportional to molality. D) inversely proportional to mole fraction. E) directly proportional to molarity. 49. Calculate the molecular weight of a small protein if a 0.24-g sample dissolved in 108 ml of water has an osmotic pressure of 9.5 mmhg at 22 C. (R = L atm/(k mol)) A) g/mol B) g/mol C) 5.7 g/mol D) g/mol E) g/mol 50. What is the freezing point of an aqueous 1.66 m CaCl 2 solution? (K f for water is C/m.) A) 9.3 C B) 3.1 C C) 9.3 C D) 0.0 C E) 3.1 C

11 PX Answer Section 1. ANS: C PTS: 1 DIF: easy REF: 11.1 OBJ: Compare a gas, a liquid, and a solid using a kinetic-molecular theory description. KEY: properties of liquids 2. ANS: A PTS: 1 DIF: easy REF: 11.2 OBJ: Define melting, freezing, vaporization, sublimation, and condensation. TOP: phases phase transitions 3. ANS: A PTS: 1 DIF: moderate REF: 11.2 OBJ: Define vapor pressure. TOP: phases phase transitions 4. ANS: C PTS: 1 DIF: easy REF: 11.2 OBJ: Define boiling point. TOP: phases phase transitions 5. ANS: A PTS: 1 DIF: easy REF: 11.2 OBJ: Calculate the heat required for a phase change of a given mass of substance. (Example 11.1) TOP: phases phase transitions 6. ANS: E PTS: 1 DIF: moderate REF: 11.2 OBJ: Calculate the heat required for a phase change of a given mass of substance. (Example 11.1) TOP: phases phase transitions KEY: phase transition enthalpy change 7. ANS: C PTS: 1 DIF: easy REF: 11.2 OBJ: Describe the general dependence of the vapor pressure (in P) on the temperature (T). TOP: phases phase transitions KEY: vapor pressure 8. ANS: D PTS: 1 DIF: moderate REF: 11.2 OBJ: Calculate the vapor pressure at a given temperature. (Example 11.2) TOP: phases phase transitions KEY: Clausius-Clapeyron equation 9. ANS: B PTS: 1 DIF: moderate REF: 11.3 OBJ: Define phase diagram. TOP: phases phase transitions KEY: phase diagram 10. ANS: E PTS: 1 DIF: easy REF: 11.3 OBJ: Define phase diagram. TOP: phases phase transitions KEY: phase diagram 11. ANS: A PTS: 1 DIF: easy REF: 11.3 OBJ: Describe the melting-point curve and the vapor-pressure curves (for the liquid and the solid) in a phase diagram. TOP: phases phase transitions KEY: phase diagram melting-point curve 12. ANS: D PTS: 1 DIF: easy REF: 11.4 OBJ: Describe the phenomenon of capillary rise. KEY: properties of liquids 13. ANS: C PTS: 1 DIF: easy REF: 11.4 OBJ: Define viscosity. KEY: properties of liquids viscosity

12 14. ANS: D PTS: 1 DIF: easy REF: 11.5 OBJ: Relate the properties of liquids to the intermolecular forces involved. KEY: intermolecular forces 15. ANS: A PTS: 1 DIF: easy REF: 11.5 OBJ: Relate the properties of liquids to the intermolecular forces involved. KEY: intermolecular forces hydrogen bonding 16. ANS: C PTS: 1 DIF: easy REF: 11.5 OBJ: Relate the properties of liquids to the intermolecular forces involved. KEY: intermolecular forces 17. ANS: C PTS: 1 DIF: easy REF: 11.5 OBJ: Relate the properties of liquids to the intermolecular forces involved. KEY: intermolecular forces 18. ANS: E PTS: 1 DIF: easy REF: 11.5 OBJ: Relate the properties of liquids to the intermolecular forces involved. KEY: intermolecular forces hydrogen bonding 19. ANS: D PTS: 1 DIF: moderate REF: 11.5 OBJ: Relate the properties of liquids to the intermolecular forces involved. KEY: intermolecular forces 20. ANS: E PTS: 1 DIF: easy REF: 11.5 OBJ: Define hydrogen bonding. KEY: intermolecular forces hydrogen bonding 21. ANS: E PTS: 1 DIF: easy REF: 11.5 OBJ: Identify the intermolecular forces in a substance. (Example 11.5) KEY: intermolecular forces hydrogen bonding 22. ANS: E PTS: 1 DIF: easy REF: 11.5 OBJ: Identify the intermolecular forces in a substance. (Example 11.5) KEY: intermolecular forces 23. ANS: E PTS: 1 DIF: easy REF: 12.1 OBJ: Types of Solutions TOP: solutions solution formation 24. ANS: D PTS: 1 DIF: easy REF: 12.2 OBJ: List the conditions that must be present to have a saturated solution, to have an unsaturated solution, and to have a supersaturated solution. TOP: solutions solution formation 25. ANS: C PTS: 1 DIF: easy REF: 12.2 OBJ: Determine when a molecular solution will form when substances are mixed. TOP: solutions solution formation KEY: solubility ionic solution

13 26. ANS: C PTS: 1 DIF: easy REF: 12.3 OBJ: State the general trends of the solubility of gases and solids with temperature. TOP: solutions solution formation KEY: effect of temperature and pressure on solubility temperature change 27. ANS: A PTS: 1 DIF: easy REF: 12.3 OBJ: State the general trends of the solubility of gases and solids with temperature. TOP: solutions solution formation 28. ANS: C PTS: 1 DIF: easy REF: 12.3 OBJ: Explain how the solubility of a gas changes with temperature. TOP: solutions solution formation KEY: effect of temperature and pressure on solubility 29. ANS: B PTS: 1 DIF: moderate REF: 12.3 OBJ: Apply Henry s law. (Example 12.1) TOP: solutions solution formation KEY: effect of temperature and pressure on solubility Henry's law 30. ANS: A PTS: 1 DIF: moderate REF: 12.3 OBJ: Apply Henry s law. (Example 12.1) TOP: solutions solution formation 31. ANS: C PTS: 1 DIF: easy REF: 12.4 OBJ: Define colligative property. TOP: solutions colligative properties 32. ANS: B PTS: 1 DIF: moderate REF: 12.4 OBJ: Define colligative property. TOP: solutions colligative properties 33. ANS: D PTS: 1 DIF: easy REF: 12.4 OBJ: Define molarity. TOP: solutions colligative properties KEY: expressing concentration 34. ANS: E PTS: 1 DIF: easy REF: 12.4 OBJ: Define molarity. TOP: solutions colligative properties KEY: expressing concentration 35. ANS: A PTS: 1 DIF: easy REF: 12.4 OBJ: Calculate mass percentage of solute. (Example 12.2) TOP: solutions colligative properties 36. ANS: A PTS: 1 DIF: easy REF: 12.4 OBJ: Calculate mass percentage of solute. (Example 12.2) TOP: solutions colligative properties KEY: expressing concentration mass percentage of solute 37. ANS: D PTS: 1 DIF: moderate REF: 12.4 OBJ: Calculate mass percentage of solute. (Example 12.2) TOP: solutions colligative properties KEY: expressing concentration conversion of concentration units 38. ANS: D PTS: 1 DIF: easy REF: 12.4

14 OBJ: Calculate the molality of solute. (Example 12.3) TOP: solutions colligative properties KEY: expressing concentration molality 39. ANS: B PTS: 1 DIF: moderate REF: 12.4 OBJ: Calculate the molality of solute. (Example 12.3) TOP: solutions colligative properties KEY: expressing concentration molality 40. ANS: A PTS: 1 DIF: easy REF: 12.4 OBJ: Calculate the mole fraction of components. (Example 12.4) TOP: solutions colligative properties KEY: expressing concentration mole fraction 41. ANS: D PTS: 1 DIF: moderate REF: 12.4 OBJ: Calculate the mole fraction of components. (Example 12.4) TOP: solutions colligative properties KEY: expressing concentration conversion of concentration units 42. ANS: D PTS: 1 DIF: easy REF: 12.5 OBJ: Calculate vapor-pressure lowering. (Example 12.9) TOP: solutions colligative properties KEY: vapor pressure of a solution vapor pressure lowering 43. ANS: D PTS: 1 DIF: difficult REF: 12.6 OBJ: Define boiling point elevation and freezing-point depression. TOP: solutions colligative properties KEY: boiling point elevation 44. ANS: C PTS: 1 DIF: easy REF: 12.6 OBJ: Calculate boiling-point elevation and freezing-point depression. (Example 12.10) TOP: solutions colligative properties KEY: freezing point depression 45. ANS: B PTS: 1 DIF: easy REF: 12.6 OBJ: Calculate the molecular mass from freezing-point depression. (Example 12.12) TOP: solutions colligative properties KEY: freezing point depression 46. ANS: C PTS: 1 DIF: moderate REF: 12.6 OBJ: Calculate the molecular mass from freezing-point depression. (Example 12.12) TOP: solutions colligative properties KEY: freezing point depression 47. ANS: E PTS: 1 DIF: easy REF: 12.7 OBJ: Calculate osmotic pressure. (Example 12.13) TOP: solutions colligative properties KEY: osmotic pressure 48. ANS: E PTS: 1 DIF: easy REF: 12.7 OBJ: Calculate osmotic pressure. (Example 12.13) TOP: solutions colligative properties KEY: osmotic pressure colligative properties 49. ANS: B PTS: 1 DIF: moderate REF: 12.7 OBJ: Calculate osmotic pressure. (Example 12.13)

15 TOP: solutions colligative properties KEY: osmotic pressure colligative properties 50. ANS: C PTS: 1 DIF: moderate REF: 12.8 OBJ: Determine the colligative properties of ionic solutions. (Example 12.14) TOP: solutions colligative properties KEY: freezing point depression

PX-III Chem 1411 Chaps 11 & 12 Ebbing

PX-III Chem 1411 Chaps 11 & 12 Ebbing 1. What is the name for the following phase change? I 2 (s) I 2 (g) A) melting B) condensation C) sublimation D) freezing E) vaporization 2. Which of the following