Chemical Engineering Chapter 13 1 Which of the following sets of conditions could exist when two liquids which are completely miscible in one another are mixed

Chapter 13: The Properties of Mixtures: Solutions and

Colloids

1. Select the type of interaction which best describes the attraction between Mg2+ ions and

water molecules.

A) dipole-dipole D) ion-induced dipole

B) dipole-induced dipole E) ion-hydrogen bond

C) ion-dipole

2. Under physiological conditions, amino acids in solution carry

A) no electrical charges.

B) a net positive charge, due to an –NH3+ group or groups.

C) a net negative charge, due to a –COO– group or groups.

D) both –NH2 and –COOH groups.

E) both –NH3+ and –COO– groups.

3. The shape of a protein molecule is determined completely by

A) hydrogen bonding.

B) ion-dipole attractions.

C) dispersion forces.

D) disulfide bridges.

E) the sequence of amino acids in the chain.

4. The most abundant molecules in the cell membranes of most species are

A) proteins. B) sugars. C) phospholipids. D) fatty acids. E) steroids.

5. Which, if any, of the following features is common to soaps, detergents, phospholipids,

and channel-forming antibiotics?

A) They all contain fatty acids.

B) They all contain phosphate groups.

C) They all contain polypeptide chains.

D) Their function depends on the dual polarity of their molecules.

E) They have none of the above features in common.

Chapter 13: The Properties of Mixtures: Solutions and Colloids

6. Consider the expression below, showing the terms which contribute to the heat of

solution, Hsoln:

Hsoln = Hsolute + Hsolvent + Hmix

Which of the following sets correctly shows the signs (positive or negative) of the three terms

on the right hand side of the equation?

A) Hsolute > 0; Hsolvent > 0; Hmix > 0 D) Hsolute < 0; Hsolvent < 0; Hmix > 0

B) Hsolute < 0; Hsolvent < 0; Hmix < 0 E) Hsolute < 0; Hsolvent > 0; Hmix < 0

C) Hsolute > 0; Hsolvent > 0; Hmix < 0

7. Which of the following ions will be expected to have the most negative heat of

hydration, Hhydr?

A) Na+ B) Cs+ C) Ca2+ D) F– E) I–

8. Which of the following sets of conditions could exist when two liquids which are

completely miscible in one another are mixed?

A) Hsoln > 0, entropy of system decreases

B) Hsoln  0, entropy of system decreases

C) Hsoln  0, entropy change of system  0

D) Hsoln  0, entropy of system increases

E) none of the above

9. If a solute dissolves in an endothermic process

A) H bonds must exist between solvent and solute.

B) strong ion-dipole forces must exist in the solution.

C) the solute must be a gas.

D) the entropy of the solution is immaterial.

E) the entropy of the solution must be greater than that of its pure components.

10. When two pure substances are mixed to form a solution

A) heat is released. D) there is a decrease in entropy.

B) heat is absorbed. E) entropy is conserved.

C) there is an increase in entropy.

11. Based only on the relative lattice energies of the compounds below, which one would be

expected to have the lowest solubility in water?

A) NaBr B) CaS C) NaOH D) KI E) CsCl

Chapter 13: The Properties of Mixtures: Solutions and Colloids

12. A solution of sucrose (sugar) in water is in equilibrium with solid sucrose. If more solid

sucrose is now added, with stirring,

A) the concentration of the solution will increase.

B) the concentration of the solution will decrease.

C) the concentration of the solution will remain the same.

D) the volume of solution will increase.

E) a supersaturated solution will be produced.

13. Which of the following pairs of ions is arranged so that the ion with the smaller charge

density is listed first?

A) K+, Rb+

B) Cl–, K+

C) Cl–, Br–

D) Ca2+, Ba2+

E) None of the above pairs are arranged in this way.

14. Which of the following pairs of ions is arranged so that the ion with the larger (i.e., more

negative) heat of hydration is listed first?

A) Br–, K+

B) Mg2+, Sr 2+

C) Ca2+, Sc3+

D) Na+, Li+

E) None of the above are arranged in this way.

15. The Henry’s Law constant (k) for carbon monoxide in water at 25°C is 9.71 × 10–4

mol/(L·atm). How many grams of CO will dissolve in 1.00 L of water if the partial pressure of

CO is 2.75 atm?

A) 3.53 × 10–4 g D) 7.48 × 10–2 g

B) 2.67 × 10–3 g E) none of the above

C) 9.89 × 10–3 g

16. Methane has a Henry’s Law constant (k) of 9.88 × 10–2 mol/(L·atm) when dissolved in

benzene at 25°C. How many grams of CH4 will dissolve in 3.00 L of benzene if the partial

pressure of CH4 is 1.48 atm?

A) 0.0667 g B) 0.146 g C) 2.34 g D) 4.83 g E) 7.02 g

Chapter 13: The Properties of Mixtures: Solutions and Colloids

17. Soda drinks bubble when the bottle is opened because

A) the temperature of the soda increases.

B) exposure to atmospheric pressure squeezes the carbon dioxide from solution.

C) the partial pressure of carbon dioxide above the solution is reduced.

D) atmospheric nitrogen molecules displace carbon dioxide molecules.

E) the Henry’s law constant changes due to the change in pressure.

18. A saturated solution of carbon dioxide in water contains 3.00 g of CO2 when the CO2

partial pressure is 8.0 atm. What mass of CO2 will escape if the partial pressure is lowered to 3.2

atm?

A) 0.90 g B) 1.20 g C) 1.40 g D) 1.80 g E) 2.20 g

19. For a given solution, which of the following concentration values will change as

temperature changes?

A) mass percent D) molarity

B) molality E) none of the above

C) mole fraction

20. Potassium fluoride is used for frosting glass. Calculate the molarity of a solution

prepared by dissolving 78.6 g of KF in enough water to produce 225 mL of solution.

A) 0.304 M B) 0.349 M C) 1.35 M D) 3.29 M E) 6.01 M

21. Potassium hydrogen phosphate is used in the preparation of non-dairy powdered

creamers. Calculate the molarity of a solution prepared by dissolving 238 g of K2HPO4 in

enough water to produce 275 mL of solution.

A) 0.732 M B) 0.865 M C) 2.66 M D) 4.97 M E) none of the above

22. Calculate the molarity of a solution prepared by diluting 1.85 L of 6.5 M KOH to 11.0 L.

A) 0.28 M B) 0.91 M C) 1.1 M D) 3.1 M E) 3.9 M

23. What volume of concentrated (14.7 M) phosphoric acid is needed to prepare 25.0 L of

3.0 M H3PO4?

A) 0.20 L B) 0.57 L C) 1.8 L D) 3.6 L E) 5.1 L

Chapter 13: The Properties of Mixtures: Solutions and Colloids

24. Saccharin, one of the first non-nutritive sweeteners used in soft-drinks, is 500 times

sweeter than sugar in dilute aqueous solutions. The solubility of saccharin is 1.00 gram per 290

mL of solution. What is the molarity of a saturated saccharin solution?

(saccharin = 183.2 g/mol)

A) 0.0188 M B) 0.632 M C) 1.58 M D) 3.45 M E) none of the above

25. Which of the following statements describes the correct method of preparation of 1.00 L

of a 2.0 M urea solution? urea = 60.06 g/mol

A) Dissolve 120 g of urea in 1.00 kg of distilled water.

B) Dissolve 120 g of urea in 880 g of distilled water.

C) Dissolve 120 g of urea in enough distilled water to produce 1.00 L of solution.

D) Dissolve 120 g of urea in 1.00 liter of distilled water.

E) The density of urea is needed in order to do this calculation.

26. Copper(II) bromide is used as a wood preservative. What mass of CuBr2 is needed to

prepare 750.0 mL of a 1.25 M solution?

A) 134 g B) 209 g C) 372 g D) 938 g E) > 1 kg

27. What is the molality of a solution prepared by dissolving 86.9 g of diethyl ether, C4H10O,

in 425 g of benzene, C6H6?

A) 0.362 m B) 0.498 m C) 2.01 m D) 2.76 m E) none of the above

28. Calcium nitrite is used as a corrosion inhibitor in lubricants. What is the molality of a

solution prepared by dissolving 18.5 g of calcium nitrite in 83.5 g of distilled water?

A) 0.0342 m B) 0.0855 m C) 0.222 m D) 0.444 m E) 1.68 m

29. Cadmium bromide is used in photography and lithography. Calculate the molality of a

solution prepared by dissolving 45.38 g of CdBr2 in 375.0 g of water.

A) 0.03035 m D) 0.4446 m

B) 0.01600 m E) none of the above

C) 0.1210 m

Chapter 13: The Properties of Mixtures: Solutions and Colloids

30. Isoamyl salicylate ( = 208.25 g/mol) has a pleasant aroma and is used in perfumes

and soaps. Which of the following combinations gives a 0.75 m solution of isoamyl salicylate in

ethyl alcohol (d = 0.7893 g/mL)?

A) 117.2 g isoamyl salicylate in 950.0 mL of ethyl alcohol

B) 117.2 g isoamyl salicylate in 750.0 mL of ethyl alcohol

C) 117.2 g isoamyl salicylate in 750.0 mL of solution

D) 117.2 g isoamyl salicylate in 592.0 g of ethyl alcohol

E) none of the above

31. The chemist, Anna Lytic, must prepare 1.00 kg of 15.0% (w/w) acetic acid using a stock

solution which is 36.0% (w/w) acetic acid (d = 1.045 g/mL). Which of the following

combinations will give her the solution she wants?

A) 417 mL of 36% acetic acid in 583 mL of distilled water

B) 417 g of 36% acetic acid in 583 g of distilled water

C) 360 mL of 36% acetic acid in 640 mL of distilled water

D) 360 g of 36% acetic acid in 640 g of distilled water

E) 150 g of 36% acetic acid in 850 g of distilled water

32. The solubility of the oxidizing agent potassium permanganate is 7.1 g per 100.0 g of

water at 25°C. What is the mole fraction of potassium permanganate in this solution?

A) 0.0080 B) 0.0086 C) 0.066 D) 0.45 E) 0.48

33. What is the mole fraction of Ar in a mixture containing 10.1 g of Ne, 79.9 g of Ar, and

83.8 g of Kr?

A) 0.40 B) 0.25 C) 0.20 D) 0.14 E) 0.058

34. A solution of ethanol (C2H6O) in water is sometimes used as a disinfectant. 1.00 L of

this solution contains 553 g of ethanol and 335 g of water. What is the mole fraction of ethanol

in this solution?

A) 0.377 B) 0.392 C) 0.553 D) 0.608 E) 0.623

35. A solution of ethanol (C2H6O) in water is sometimes used as a disinfectant. 1.00 L of

this solution contains 553 g of ethanol and 335 g of water. What is the molality of the ethanol in

this solution?

A) 0.392 m B) 0.608 m C) 13.5 m D) 33.6 m E) 35.8 m

Chapter 13: The Properties of Mixtures: Solutions and Colloids

36. Aqueous ammonia is commercially available in a solution that is 28% (w/w) ammonia.

What is the mole fraction of ammonia in such a solution?

A) 0.017 B) 0.023 C) 0.012 D) 0.24 E) 0.29

37. Sodium hydroxide is a common ingredient in drain cleaners such as Drano. The mole

fraction of sodium hydroxide in a saturated aqueous solution is 0.310. What is the molality of

the solution?

A) 0.310 m B) 0.690 m C) 1.24 m D) 12.4 m E) 25.0 m

38. The mole fraction of potassium nitrate in an aqueous solution is 0.0194. The solution’s

density is 1.0627 g/mL. Calculate the molarity of the solution.

A) 0.0194 M B) 0.981 M C) 1.05 M D) 1.96 M E) 19.4 M

39. A 0.89% (w/v) sodium chloride solution is referred to as physiological saline solution

because it has the same concentration of salts as human blood. What is the molarity of a

physiological saline solution?

A) 0.0028 M B) 0.015 M C) 0.15 M D) 0.30 M E) 0.35 M

40. A 2.0% (w/v) solution of sodium hydrogen citrate, Na2C6H6O7, which also contains

2.5% (w/v) of dextrose, C6H12O6, is used as an anticoagulant for blood which is to be used for

transfusions. What is the molarity of the sodium hydrogen citrate in the solution?

A) 0.085 M B) 0.19 M C) 0.53 M D) 1.2 M E) 1.3 M

41. Procaine hydrochloride ( = 272.77 g/mol) is used as a local anesthetic. Calculate the

molarity of a 4.666 m solution which has a density of 1.1066 g/mL.

A) 2.272 M

B) 4.056 M

C) 4.216 M

D) 4.666 M

E) none of the above

42. The concentration of iodine in sea water is 60. parts per billion by mass. If one assumes

that the iodine exists in the form of iodide anions, what is the molarity of iodide in sea water?

(The density of sea water is 1.025 g/mL.)

A) 4.8 × 10–13 M D) 4.7 × 10–4 M

B) 4.8 × 10–10 M E) 4.7 × 10–1 M

C) 4.8 × 10–7 M

Chapter 13: The Properties of Mixtures: Solutions and Colloids

43. Children under the age of six with more than 0.10 ppm of lead in their blood can suffer a

reduction in I.Q. or have behavior problems. What is the molality of a solution which contains

0.10 ppm of lead?

A) 4.8 × 10–10 m D) 4.8 × 10–1 m

B) 4.8 × 10–7 m E) none of the above

C) 4.8 × 10–4 m

44. Colligative properties depend on

A) the chemical properties of the solute. D) the molar mass of the solute.

B) the chemical properties of the solvent. E) the number of particles dissolved.

C) the masses of the individual ions.

45. Raoult’s Law relates the vapor pressure of the solvent above the solution to its mole

fraction in the solution. Which of the following is an accurate statement?

A) Raoult’s Law applies exactly to all solutions.

B) Raoult’s Law works best when applied to concentrated solutions.

C) Raoult’s Law works best when applied to dilute solutions.

D) Raoult’s Law applies only to non-ideal solutions.

E) None of the above statements is accurate.

46. The vapor pressure of pure acetone (propanone) is 266 torr. When a non-volatile solute

is added, the vapor pressure of acetone above the solution falls to 232 torr. What is the mole

fraction of the non-volatile solute in the solution?

A) 0.87 B) 0.69 C) 0.32 D) 0.13 E) 0.045

47. The vapor pressure of pure acetone (propanone) is 266 torr. When a non-volatile solute

is added, the vapor pressure of acetone above the solution falls to 232 torr. What is the mole

fraction of acetone in the solution?

A) 0.87 B) 0.69 C) 0.32 D) 0.13 E) 0.045

48. From the following list of aqueous solutions and water, select the one with the highest

boiling point.

A) 1.0 m KNO3 D) 2.0 m C12H22O11 (sucrose)

B) 0.75 m NaCl E) pure water

C) 0.75 m CuCl2

Chapter 13: The Properties of Mixtures: Solutions and Colloids

49. What concentration of aqueous FeCl3 would have the same osmotic pressure as a 0.20

M solution of CaCl2 at the same temperature, assuming ideal behavior?

A) 0.60 M B) 0.40 M C) 0.30 M D) 0.15 M E) 0.10 M

50. From the following list of aqueous solutions and water, select the one with the lowest

freezing point.

A) 0.75 m (NH4)3PO4 D) 1.5 m CH3OH, methyl alcohol

B) 1.0 m CaSO4 E) pure water

C) 1.0 m LiClO4

51. Which of the following aqueous solutions should demonstrate the most ideal behavior?

A) 0.1 M K2SO4 D) 0.1 M MgSO4

B) 0.1 M CaCl2 E) 0.1 M NaCl

C) 3.0 M LiF

52. Which of the following aqueous solutions should demonstrate the most non-ideal

behavior?

A) 0.1 M NaI D) 2.0 M CuCl2

B) 0.2 M CuSO4 E) 2.0 M CsCl

C) 0.5 M KBr

53. Select the strongest electrolyte from the following set.

A) CH3CH2OH, ethanol

B) LiNO3

C) C6H12O6, glucose

D) CCl4

E) HF

54. Select the weakest electrolyte from the following set.

A) Na2SO4 D) CaCl2

B) KCl E) LiOH

C) CH3CH2COOH, propionic acid

55. How many moles of sulfate ions are present in 1.0 L of 0.5 M Li2SO4?

A) 0.5 mol B) 1.0 mol C) 1.5 mol D) 2.0 mol E) 3.0 mol

Chapter 13: The Properties of Mixtures: Solutions and Colloids

56. How many moles of bromide ions are present in 750.0 mL of 1.35 M MgBr2?

A) 0.506 mol

B) 1.01 mol

C) 2.03 mol

D) 3.04 mol

E) none of the above

57. How many moles of solute particles are present in 100.0 mL of 2.50 M (NH4)3PO4?

A) 0.100 mol B) 0.250 mol C) 0.500 mol D) 0.750 mol E) l.00 mol

58. Two aqueous are prepared: 1.00 m Na2CO3 and 1.00 m LiCl. Which of the following

statements is true?

A) The Na2CO3 solution has a higher osmotic pressure and higher vapor pressure than

the LiCl solution.

B) The Na2CO3 solution has a higher osmotic pressure and higher boiling point than

the LiCl solution.

C) The Na2CO3 solution has a lower osmotic pressure and lower vapor pressure than

the LiCI solution.

D) The Na2CO3 solution has a lower osmotic pressure and higher boiling point than

the LiCl solution.

E) None of the above statements is true.

59. Two aqueous solutions are prepared: 2.0 m Cu(NO3)2 and 2.0 m NaBr. Which of the

following statements is true?

A) The Cu(NO3)2 solution has a higher vapor pressure and lower freezing point than

the NaBr solution.

B) The Cu(NO3)2 solution has a higher vapor pressure and higher freezing point than

the NaBr solution.

C) The Cu(NO3)2 solution has a lower vapor pressure and lower freezing point than

the NaBr solution.

D) The Cu(NO3)2 solution has a lower vapor pressure and higher freezing point than

the NaBr solution.

E) None of the above statements is true.

60. Which of the following aqueous solutions will have the lowest osmotic pressure?

A) 0.10 m KOH D) 0.05 m BaCl2

B) 0.10 m RbCl E) 0.10 m K2SO4

C) 0.05 m CaSO4

Chapter 13: The Properties of Mixtures: Solutions and Colloids

61. Which of the following aqueous liquids will have the lowest freezing point?

A) 0.5 m C12H22O11 (sucrose) D) 0.5 m Li3PO4

B) 0.5 m Ca(NO3)2 E) pure water

C) 0.5 m NiSO4

62. Calculate the vapor pressure of a solution prepared by dissolving 0.500 mol of a non-

volatile solute in 275 g of hexane ( = 86.18 g/mol) at 49.6°C. P°hexane = 400.0 torr at 49.6°C.

A) 54 torr B) 154 torr C) 246 torr D) 346 torr E) 400. torr

63. Safrole is used as a topical antiseptic. Calculate the vapor pressure of a solution prepared

by dissolving 0.75 mol of safrole in 950 g of ethanol ( = 46.07 g/mol). P°ethanol = 50.0 torr at

25°C.

A) 1.8 torr B) 11 torr C) 15 torr D) 40 torr E) 48 torr

64. Diethyl ether has a vapor pressure of 400.0 torr at 18°C. When a sample of benzoic acid

is dissolved in ether, the vapor pressure of the solution is 342 torr. What is the mole fraction of

benzoic acid in the solution?

A) 0.0169 B) 0.0197 C) 0.145 D) 0.855 E) none of the above

65. Determine the freezing point of a solution which contains 0.31 mol of sucrose in 175 g

of water. Kf = 1.86°C/m

A) 3.3°C B) 1.1°C C) 0.0°C D) –1.1°C E) –3.3°C

66. Benzaldehyde ( = 106.1 g/mol), also known as oil of almonds, is used in the

manufacture of dyes and perfumes and in flavorings. What would be the freezing point of a

solution prepared by dissolving 75.00 g of benzaldehyde in 850.0 g of ethanol? Kf = 1.99°C/m,

freezing point of pure ethanol = –117.3°C.

A) –117.5°C B) –118.7°C C) –119.0°C D) –120.6°C E) < –121°C

67. Carbon tetrachloride, once widely used in fire extinguishers and as a dry cleaning fluid,

has been found to cause liver damage to those exposed to its vapors over long periods of time.

What is the boiling point of a solution prepared by dissolving 375 g of sulfur (S8, = 256.5

g/mol) in 1250 g of CCl4? Kb = 5.05°C/m, boiling point of pure CCl4 = 76.7°C?

A) 70.8°C B) 75.2°C C) 78.2°C D) 82.6°C E) >85°C

Chapter 13: The Properties of Mixtures: Solutions and Colloids

68. Barbiturates are synthetic drugs used as sedatives and hypnotics. Barbital ( = 184.2

g/mol) is one of the simplest of these drugs. What is the boiling point of a solution prepared by

dissolving 42.5 g of barbital in 825 g of acetic acid?

Kb = 3.07°C/m; boiling point of pure acetic acid = 117.9°C

A) 117.0°C B) 117.7°C C) 118.1°C D) 118.8°C E) >120°C

69. Dimethylglyoxime, DMG, is an organic compound used to test for aqueous nickel(II)

ions. A solution prepared by dissolving 65.0 g of DMG in 375 g of ethanol boils at 80.3°C. What

is the molar mass of DMG?

Kb = 1.22°C/m, boiling point of pure ethanol = 78.5°C

A) 44.1 g/mol

B) 65.8 g/mol

C) 117 g/mol

D) 131.6 g/mol

E) 553 g/mol

70. Hexachlorophene is used as a disinfectant in germicidal soaps. What mass of

hexachlorophene ( = 406.9 g/mol) must be added to 125 g of chloroform to give a solution

with a boiling point of 62.60°C? Kb = 3.63°C/m, boiling point of pure chloroform = 61.70°C

A) 12.6 g B) 17.2 g C) 31.0 g D) 34.4 g E) 101 g

71. Cinnamaldehyde ( = 132.15 g/mol) is used as a flavoring agent. What mass of

cinnamaldehyde must be added to 175 g of ethanol to give a solution whose boiling point is

82.7°C?

Kb = 1.22°C/m, boiling point of pure ethanol = 78.5°C

A) 62.4 g B) 67.8 g C) 76.2 g D) 78.5 g E) 79.6 g

72. Calculate the freezing point of a solution made by dissolving 3.50 g of potassium

chloride ( = 74.55 g/mol) in 100.0 g of water. Assume ideal behavior for the solution; Kf =

1.86°C/m.

A) –1.7°C B) –0.9°C C) 0.0°C D) 0.9°C E) 1.7°C

73. A 0.100 m K2SO4 solution has a freezing point of –0.43°C. What is the van’t Hoff factor

for this solution? Kf = 1.86°C/m

A) 0.77 B) 1.0 C) 2.3 D) 3.0 E) >3.0

Chapter 13: The Properties of Mixtures: Solutions and Colloids

74. A 0.100 m MgSO4 solution has a freezing point of –0.23°C. What is the van’t Hoff factor

for this solution? Kf = 1.86°C/m

A) 0.62 B) 1.0 C) 1.2 D) 2.0 E) 4.0

75. Human blood has a molar concentration of solutes of 0.30 M. What is the osmotic

pressure of blood at 25°C?

A) 0.012 atm B) 0.62 atm C) 6.8 atm D) 7.3 atm E) >10. atm

76. Lysine is an amino acid that is an essential part of nutrition but which is not synthesized

by the human body. What is the molar mass of lysine if 750.0 mL of a solution containing 8.60 g

of lysine has an osmotic pressure of 1.918 atm?

Temperature = 25.0°C

A) 110. g/mol

B) 146 g/mol

C) 220. g/mol

D) 1340 g/mol

E) 1780 g/mol

77. Which one of the following pairs of dispersed phases and dispersing media can never

form a colloid?

A) solid and gas D) liquid and liquid

B) liquid and gas E) gas and gas

C) solid and solid

78. An emulsion is a dispersion consisting of a

A) solid in a liquid. D) liquid in a solid.

B) liquid in a liquid. E) gas in a solid.

C) gas in a liquid.

79. The Tyndall effect

A) is observed in concentrated solutions.

B) is observed only in dilute solutions.

C) is observed in colloidal dispersions.

D) is caused by Brownian motion.

E) is used to determine the osmotic pressure of solutions.

Chapter 13: The Properties of Mixtures: Solutions and Colloids

80. List three important intermolecular forces that operate in DNA, and explain what parts of

the molecule are involved in these forces.

81. List five important intermolecular forces that operate in globular proteins, and explain

what parts of the molecule are involved in these forces.

82. The density of pure water at 25°C is 0.997 g/mL. Considering water as being both

solvent and solute, calculate its molarity.

83. A 50.0 % (w/w) solution of sulfuric acid (H2SO4) in water has a density of 1.395 g/mL.

What is its molarity?

84. A 7.112 M solution of sulfuric acid (H2SO4) in water has a density of 1.395 g/mL. What

is its molality?

Chapter 13: The Properties of Mixtures: Solutions and Colloids

85. Octane and nonane are liquids which are components of gasoline. Their vapor pressures

at 25°C are 13.9 torr and 4.7 torr, respectively. What is the vapor pressure of a mixture

consisting of 1 mole of each of these compounds?

86. If a 100-mL sample of a volatile liquid such as diethyl ether is introduced into a 250-mL

flask which is immediately sealed, the pressure inside will increase above atmospheric pressure.

Explain.

87. If the shell of a raw egg is carefully dissolved away, and the egg in its flexible membrane

is then placed in distilled water, the egg’s volume will expand. Explain.

88. 1.00 L of an aqueous solution contains 1.52 g of a compound used in antifreeze. If the

osmotic pressure of this solution at 20.0°C is 448 torr, calculate the molar mass of the antifreeze

compound.

89. Predict the ideal van’t Hoff factor (i) for each of the following solutes:

a. CaCl2

b. Fe2(SO4)3

c. NH4Cl

90. A 0.137 m solution of sodium ferrocyanide (Na4Fe(CN)6.10H2O) in water has a freezing

point depression of 0.755°C. Calculate the van’t Hoff factor (i) under these conditions. (Kf =

1.86°C/m)

Chapter 13: The Properties of Mixtures: Solutions and Colloids

91. Classify the following as either solutions or colloids. If a colloid, name the type of colloid

and identify both the dispersed and the dispersing phases.

a. glucose in water

b. smoke in air

c. carbon dioxide in air

d. milk

92. All solutions are mixtures.

93. Helical segments of protein molecules arise through hydrogen bonding between C=O

and N–H groups.

94. The backbone of a protein chain consists of carbon, nitrogen, and oxygen atoms.

95. In general, water is a good solvent for both polar and non-polar compounds.

96. Gases with high boiling points tend to be more soluble in water than ones with low

boiling points.

97. The heat of solution is the total enthalpy change when a solution is formed from the

separated solute and solvent.

98. Heats of solution may be either positive or negative.

99. Heats of hydration may be either positive or negative.

100. The larger the ion, the greater in magnitude will be its heat of hydration.

101. The solubility of gases in water increases with increase in the pressure of the gas.

Chapter 13: The Properties of Mixtures: Solutions and Colloids

102. If the density of a solution is less than 1.0 g/mL, its molarity will be greater than its

molality.

103. Raoult’s Law relates the vapor pressure of a solvent above a solution to the mole fraction

of the solvent and the vapor pressure of the pure solvent.

104. Ideal solutions do not conform to Raoult’s Law.

105. Electrolyte solutions generally behave less ideally as the solute concentration increases.

106. Colloidal particles may be either solids, liquids, or gases.