Chem 1120 - Chapter 11: States of Matter: Liquids & SolidsPractice Quiz 1

1. Calculate the amount of heat absorbed by 10.0 grams of ice at -15.0°C in converting it to liquid water at 50.0°C. (Sp. heat of H2O(s) = 2.09 J/g °C, Sp. heat of H2O(l) = 4.18 J/g °C, heat of fusion of H2O(s) = 333 J/g)

a) 5.73 x 103 Jb) 6.76 x 102 Jc) 1.70 x 102 Jd) 2.83 x 103 Je) 3.29 x 103 J

2. Some solids can be converted directly to the vapor phase by heating. The process is called:

a) fusionb) sublimationc) vaporizationd) condensatione) distillation

3. A sketch of the phase diagram (not to scale) of water is given below. Which statement is FALSE?

a) Line AD is the sublimation curve - solid and vapor are in equilibrium.b) Point A is the triple point - solid, liquid, and vapor are at equilibrium.c) Line AC is the vapor pressure curve - liquid and gas (vapor) are in equilibrium.d) Line AB is the melting curve - solid and liquid are in equilibrium.

e) The slope of line AB is negative showing that as the liquid is cooled, the molecules get closer and closer together as they solidify.

4. In a body-centered cubic lattice, how many atoms are present per in a unit cell?

a) oneb) twoc) threed) foure) five

5. In any cubic lattice, an atom lying at the corner of a unit cell is shared equally by how many unit cells?

a) oneb) twoc) eightd) foure) sixteen

6. Which one of the following statements is NOT applicable to COVALENT solids?

a) The units that occupy the lattice points are atoms.b) The binding forces in covalent solids are shared electrons.c) Covalent solids have low melting points.d) Covalent solids are typically very hard.e) Covalent solids typically do not conduct electric current well.

7. Which one of the following substances is INCORRECTLY matched with the kind of solid it forms?

Substance Kind of Solid

a) sulfur dioxide molecular

b) Graphite covalent

c) calcium bromide ionic

d) Lithium ionic

e) Methane molecular

8. Substances have properties that are related to their structures. Which of the following statements regarding properties of solids is NOT expected to be CORRECT?

a) Solid potassium should be a good conductor of electricity.b) Solid CaSO4 should sublime readily.c) Molten LiCl should be a good conductor of electricity.d) Graphite should have a high melting point.e) Solid CO2 should have a low melting point.

9. Arrange the following in order of increasing melting points: CsCl, BaCl2, diamond (c), H2, HF

----> Increasing Melting Points ---->

a) H2 less than HF less than BaCl2 less than CsCl less than diamondb) HF less than H2 less than CsCl less than BaCl2 less than diamondc) H2 less than HF less than CsCl less than BaCl2 less than diamondd) H2 less than HF less than diamond less than CsCl less than BaCl2

e) HF less than H2 less than diamond less than CsCl less than BaCl2

10. In ideal close-packed structures of metallic solids, how many nearest neighbors does a metal ion have?

a) 4b) 3c) 6d) 8e) 12

11. Metallic calcium crystallize in a face-centered cubic lattice, and the atomic radius of calcium is 1.97Å. Calculate the density of calcium. (1Å = 10-8 cm)

a) 1.28 g/cm3

b) 1.42 g/cm3

c) 1.54 g/cm3

d) 1.84 g/cm3

e) 2.11 g/cm3

12. Which one of the following statements is NOT applicable to ionic solids?

a) The binding forces in ionic solids are electrostatic attractions.b) Ionic solids have fairly high melting points. c) Most ionic solids are hard and brittle.d) The units that occupy the lattice points are ions.e) Ionic solids are usually excellent conductors of electric current.

13. How much heat is absorbed if 45 grams of sweat is evaporated from someone's skin? ΔHvap for water at body temperature is 2.41 kJ/g.

a) 115,100 Jb) 43,400 Jc) 53.6 kJd) 108,500 Je) 108.5 J

14. How much heat is released when 40.0 g of steam at 250.0°C cools and condenses to water at 30.0 °C? (Sp. heat of H2O(l) = 4.18 J/g °C, Sp. heat of H2O(g) = 2.03 J/g °C, heat of vap. of H2O(l) = 2.260 kJ/g)

a) 32.9 kJb) 122 kJc) 114 kJd) 24.0 kJe) 23.0 J

15. A sketch of a phase diagram is given below. Which statement about this diagram is NOT TRUE?

a) Increasing temperature at constant pressure can cause the solid to sublime.b) Increasing pressure at constant temperature can cause liquid to freeze.c) Increasing pressure at constant temperature can melt the solid.d) Increasing pressure at constant temperature can cause deposition of solid from gas.e) Increasing temperature at constant pressure can cause the liquid to vaporize.

16. Which substance would be expected to have the HIGHEST heat of vaporization?

a) CH3OCH3

b) CCl4

c) CH2OHCH2OHd) C2H6

e) F2

17. Which response has the following substances arranged in order of INCREASING boiling point? Ar, NaClO3, H2O, H2Se

a) NaClO3 less than H2O less than H2Se less than Arb) Ar less than H2O less than H2Se less than NaClO3

c) Ar less than NaClO3 less than H2Se less than H2Od) NaClO3 less than H2Se less than H2O less than Are) Ar less than H2Se less than H2O less than NaClO3

18. In a body-centered cubic lattice, how many atoms are contained in a unit cell?

a) oneb) fivec) threed) twoe) four

19. Metallic calcium crystallized in a face-centered cubic lattice and the atomic radius of calcium is 1.97Å. Calculate the edge length, a, of a unit cell of calcium.

a) 5.57Åb) 6.05Åc) 6.24Åd) 4.19Åe) 6.83Å

20. Which type of solid is expected for SO2?

a) hypersaturatedb) molecularc) covalentd) ionice) metallic

21. Arrange the following ionic compounds in order of increasing melting points. NaF, MgF2, AlF3, NaBr, NaI

a) MgF2 less than AlF3 less than NaF less than NaI less than NaBrb) NaF less than NaBr less than NaI less than MgF2 less than AlF3

c) AlF3 less than MgF2 less than NaF less than NaBr less than NaId) NaBr less than NaI less than NaF less than AlF3 less than MgF2

e) NaI less than NaBr less than NaF less than MgF2 less than AlF3

22. Arrange the following in order of increasing melting points: KCl, He, H2O, HF.

a) He less than HF less than H2O less than KClb) KCl less than H2O less than HF less than Hec) H2O less than He less than KCl less than HFd) He less than H2O less than HF less than KCle) H2O less than HF less than He less than KCl

KEY

1)a 2)b 3)e 4)b 5)c 6)c 7)d 8)b 9)c 10)e 11)c 12)e 13)d 14)c 15)b 16)c 17)e 18)d 19)a 20)b 21)e 22)a

1. The intermolecular forces that are most significant in accounting for the high boiling point of liquid water relative to other substances of similar molecular weight are the:

a) ion-ion attractionsb) London dispersion forcesc) hydrogen bonding forcesd) dipole-dipole attractions

2. Which of the following substances will have the highest boiling point?

a) methane (MW=16) b) butane (MW=58) c) ethyl alcohol (MW=46) d) methyl alcohol (MW=32)

3. Which of the following substances will have the lowest boiling point?

a) neonb) waterc) ammonia d) helium

4. Identify the INCORRECT statement below:

a) When the vapor pressure of a liquid equals the surrounding pressure, the liquid boils. b) The boiling point is the temperature at which the vapor pressure of the liquid equals the surrounding pressure. c) The normal boiling point is the temperature at which the vapor pressure of the liquid equals 1 atm.

d) The vapor pressure of a liquid increases as the temperature of the liquid increases. e) Easily vaporized liquids are called volatile liquids, having low vapor pressures.

5. Calculate the heat required in Joules to convert 18.0 grams of water ice at a temperature of -20° C to liquid water at the normal boiling point of water.

Given: -specific heat of ice = 2.09 J/g°C-specific heat of liquid water = 4.184 J/g°C-specific heat of water vapor = 2.03 J/g°C-molar heat of fusion of water = 6.02 kJ/mol-molar heat of vaporization of water = 40.7 kJ/mol

a) 757 Jb) 13626 Jc) 943 Jd) 108360 J

6. Based on Coulomb's law of interaction strength between ions, which of the following compounds has the highest melting point?

a) CaCl2

b) NaClc) NaFd) MgO

7. Rank the following liquids in order of increasing boiling points, from lowest to highest: He / NH3 / Ar / N2

a) He < N2 < Ar < NH3

b) He < Ar < N2 < NH3

c) NH3 < Ar < N2 < Hed) NH3 < N2 < Ar < He

8. The interaction responsible for the cohesive intermolecular forces of liquid nitrogen is:

a) hydrogen bondingb) the London dispersion forcec) dipole-dipole interactiond) covalent bonding

9. Identify the INCORRECT statement below:

a) The vapor pressure of liquid water at 100°C is 760 Torr (1 atm). b) The normal boiling point of a liquid is the temperature at which the vapor pressure of the liquid

equals 1 atm. c) The boiling point of a liquid increases as the surrounding pressure decreases. d) Vapor pressure of a liquid increases as the temperature increases. e) A liquid boils when its vapor pressure equals the surrounding pressure.

10. Calculate the energy in joules required to convert a mole of ice at -10°C to steam at 120°C. Given:

ΔHvap of H2O = 40.7 kJ/molΔHfus of H2O = 6.02 kJ/molCm (ice) = 37.6 J/mol°CCm (liquid H2O) = 75.3 J/mol°CCm (steam) = 36.5 J/mol°C

a) 8680 Jb) 356 Jc) 55,356 Jd) 196 J

11. The smallest repeat unit of a crystalline solid is called:

a) a point groupb) a lattice pointc) a unit celld) a crystalline element

12. The type of solid which is characterized as positive ions embedded in a sea of delocalized electrons is called:

a) a metallic solidb) a ionic solidc) a molecular solidd) a covalent (network) solid

13. Diamond (pure carbon) would be classified as which type of solid:

a) a metallic solidb) a ionic solidc) a molecular solidd) a covalent (network) solid

14. Which of the following intermolecular forces is INCORRECTLY assigned as the principal force in the compound given?

a) CCl4, Londonb) NH3, London

c) HF, H-bondingd) CH3OH, H-bondinge) H-Br, dipole

15. According to the following phase diagram for a substance X, which of the following statements is FALSE?

a) The normal boiling point of X is 184°C. b) At 25°C, X will boil if the pressure is lowered enough. c) X is liquid at 120°C and 1 atm. d) The melting point of X varies little with pressure.

16. Which of the following is NOT true of covalent (network) solids?

a) The units which occupy the lattice points are atoms. b) The inter-unit forces are covalent bonds. c) They typically exhibit low melting points. d) They are usually very hard. e) They are usually poor electrical conductors.

17. Chlorine has a critical temperature of 144°C and a critical pressure of 77 atm. Under which of the following conditions would Cl2 most likely be a liquid?

a) 125°C, 70 atmb) 125°C, 30 atmc) 150°C, 70 atmd) 150°C, 30 atm

18. The normal boiling point of ether is 35°C. Comparing ether and water, at the same temperature, which statement below is TRUE?

a) The vapor pressure of both liquids are the same. b) The vapor pressure of ether is greater than that of water.

c) The vapor pressure of water is greater than that of ether. d) The vapor pressure of both liquids are equal to the temperature.

19. The term used to describe resistance to flow of a liquid is:

a) surface tensionb) capillary actionc) viscosityd) vapor pressuree) vaporization

20. How many atoms are considered to belong to the face-centered cubic unit cell?

a) 1b) 2c) 4d) 6e) 8

21. Which of the following descriptions of solid type is INCORRECT?

a) Cu ; metallicb) SiO2(quartz) ; molecularc) CaCl2 ; ionicd) H2O ; moleculare) C(diamond); covalent

22. Which response lists interparticle forces (between molecules of comparable size) in order of increasing strength?

a) London < ionic < H-bonds < dipoleb) dipole < London < H-bond < ionicc) H-bond < ionic < dipole < Londond) ionic < H-bond < London < dipolee) London < dipole < H-bond < ionic

23. The molar heat of fusion for nitrogen is 710 J/mole. How many grams of N2, at its melting point, can be melted by 1080 joules of heat?

a) 43 gb) 1.5 gc) 21 gd) .065 ge) 18 g

24. On the following typical phase diagram, which statement is INCORRECT?

a) Point A corresponds to sublimation/deposition.b) Point B corresponds to the critical point, where all three phases coexist.c) Point C corresponds to the liquid phase of the substance.d) At a higher temperature and pressure than point D, the substance exists as a supercritical fluid.e) Raising the pressure from point E to point C causes the substance to condense.

25. Arrange these substances in order of INCREASING boiling point: Xe, H2, H2O, LiCl, H2S.

a) Xe < H2 < H2O < LiCl < H2Sb) Xe < H2 < H2S < H2O < LiClc) H2 < Xe < H2S < H2O < LiCld) H2 < Xe < H2O < H2S < LiCl

26. Which of the following is NOT a molecular solid?

a) solid CO2

b) solid waterc) white phosphorus (solid P4)d) S8

e) diamond

27. Which is the weakest intermolecular force among a group of molecules of comparable molecular weight (molar mass)?

a) dipole-dipoleb) Londonc) ionic bondingd) hydrogen bonding

28. Which of the following best describes the properties of a metallic solid?

a) soft, very low melting point, poor electrical conductorb) an amorphous solid with no unit cell, conducts electricity, doesn't conduct heat wellc) very hard, very high melting point, poor electrical conductord) variable hardness, variable melting point, excellent thermal conductor

29. Which of the following pure substances exhibits hydrogen bonding?

a) NH3

b) H2Sc) HCld) CH4

e) all of these do

KEY

1)c 2)c 3)d 4)e 5)b 6)d 7)a 8)b 9)c 10)c 11)c 12)a 13)d 14)b 15)b 16)c 17)a 18)b 19)c 20)c 21)b 22)e 23)a 24)b 25)c 26)e 27)b 28)d 29)a

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Chem 1120 - Chapter 12: SolutionsPractice Quiz 1

1. Which of the following statements about soaps and detergents is FALSE?

a) The polar end is attracted to grease and oil.b) They are emulsifiers for grease and oil.c) Phosphate detergents can produce pollution problems.d) They can be described as surfactants.e) They have a polar and a nonpolar end.

2. The Tyndall effect describes __________.

a) precipitation of colloidal particles using electrically charged plates.b) the scattering of light by colloidal particles.

c) reverse osmosis involving saline solutions.d) the adsorption of positive ions onto the surface of a hydrophilic solid.e) hydrophobic interactions between nonpolar molecules.

3. Which one of the following statements about soaps and soap molecules is FALSE?

a) They have a polar end.b) They have a hydrophobic end.c) They are often sodium salts of long chain fatty acids.d) The hydrophilic end of a soap molecule is attracted by grease.e) They precipitate in water that contains Fe3+ ions.

4. The dissolution process is exothermic if the amount of energy released in bringing about (a) interactions exceeds the sum of the amounts of energy absorbed in overcoming (b) and (c) interactions.

(a) (b) (c)

a) solute-solute solvent-solvent solvent-solute

b) solvent-solvent solute-solute solvent-solute

c) solvent-solute solute-solute crystal lattice

d) solute-solute crystal lattice solvent-solvent

e) solvent-solute solute-solute solvent-solvent

5. Consider the following pairs of liquids. Which numbered response contains all the pairs that are miscible and none that are immiscible?

I. benzene, C6H6, and hexane, C6H14

II. water, H2O, and methanol, CH3OHIII. water, H2O, and hexane, C6H14

a) Ib) I and IIc) II and III

d) IIe) I, II, and III

6. Which numbered response lists all of the following statements that are TRUE, and NO FALSE statements?

I. Many solids that dissolve in endothermic processes have solubilities that increase as temperature increases.II. The solubility in water of a gas that does not react with water increases as the partial pressure of that gas above the surface of the solution increases.III. Most gases that are reasonably soluble in water are polar or else they react with water or ionize in water.

a) Ib) IIc) I and IId) II and IIIe) I, II, and III

7. If the concentration of CO2 is 2.90 g of CO2 per 1.00 L of soft drink when bottled under 2.0 atm of CO2 pressure, what will be the concentration of the CO2 in the drink after it has been opened and left to come to equilibrium with the atmosphere which has a CO2 partial pressure of 3.0 x 10-4 atm?

a) 2.2 x 10-3 g CO2/Lb) 2.0 x 10-4 g CO2/Lc) 1.0 x 10-4 g CO2/Ld) 4.4 x 10-4 g CO2/Le) 4.6 x 10-2 g CO2/L

8. What is the molality of an aqueous solution that is 10.0% ethanol, C2H5OH, by mass?

a) 1.38 mb) 1.77 mc) 2.17 md) 2.42 me) 2.66 m

9. What mass of water must be used to dissolve 20.0 grams of ethanol, C2H5OH, to prepare a 0.0500 molal solution of ethanol?

a) 3.76 kgb) 4.00 kgc) 8.70 kgd) 6.35 kge) 7.18 kg

10. A solution contains 10.0 g pentane, C5H12, 10.0 g hexane, C6H14 and 10.0 g benzene, C6H6. What is the mole fraction of hexane?

a) 0.303b) 0.116c) 0.333d) 0.362e) 0.335

11. Which of these aqueous solutions would be expected to have the highest boiling point?

a) 0.100 m CaCl2

b) 0.200 m NaOHc) 0.050 m K2SO4

d) 0.050 m Al2(SO4)3

e) 0.200 m CH3OH

12. Calculate the freezing point of a solution that contains 8.0 g of sucrose (C12H22O11) in 100. g of H2O. Kf for H2O = 1.86°C/m.

a) - 0.044°Cb) - 0.22°Cc) - 0.39°Cd) - 0.44°Ce) 0.04°C

13. When 1.150 grams of an unknown nonelectrolyte dissolves in 10.0 grams of water, the solution freezes at -2.16°C. What is the molecular weight of the unknown compound? Kf for water = 1.86°C/m.

a) 88.6 g/molb) 116 g/molc) 74.2 g/mold) 99.1 g/mole) 132 g/mol

14. Calculate the mole fraction of ethyl alcohol, C2H5OH, in a solution that contains 230. grams of C2H5OH and 312 grams of benzene, C6H6.

a) 2.3b) 0.57c) 0.44d) 1.8e) 0.56

15. Which one of the following statements is FALSE?

a) All cations are hydrated in aqueous solution.b) Hydration is generally highly endothermic for ionic compoundsc) All anions are hydrated in aqueous solution.d) The heats of hydration of cations increases as their charge-to-radius ratios increase.e) All ions are hydrated in aqueous solution.

16. Calculate the osmotic pressure associated with 50.0 g of an enzyme of molecular weight 98,000 g/mol dissolved in 2600. mL of benzene at 30.0 °C.

a) 3.71 torrb) 1.96 torrc) 0.484 torrd) 2.48 torre) 1.68 torr

17. What is the vapor pressure of a aqueous solution containing 10 % (by weight) ethylene glycol (62 g/mol) at 25 °C. PH2O = 24.3 torr at 25°C?

a) 25.1 torrb) 0.761 torrc) 23.5 torrd) 21.9 torre) 18.9 torr

18. Which of the following terms is NOT generally used in describing the dissolution of solids and gases in liquids?

a) % solute by massb) molarityc) molalityd) miscibilitye) saturation

19. Calculate the molarity of a solution that contains 9.0 g of (COOH)2 in 1500. mL of solution.

a) 0.20 Mb) 0.26 Mc) 0.13 Md) 0.10 Me) 0.067 M

20. Consider the three statements below. Which numbered response contains all the statements that are TRUE and no false statements?

I. Hydration is a special case of solvation in which the solvent is water.II. The oxygen end of water molecules is attracted toward Ca2+ ions.III. The hydrogen end of water molecules is attracted toward Cl- ions.

a) I, II, and IIIb) I and IIc) IIId) Ie) II

21. If 4.27 grams of sucrose, C12H22O11, are dissolved in 15.2 grams of water, what will be the boiling point of the resulting solution? Kb for water = 0.512 °C/m.

a) 101.42 °Cb) 100.73 °Cc) 100.42 °Cd) 99.626 °Ce) 101.64 °C

22. Which one of the following statements is FALSE?

a) The solubility of a gas that does not react with the solvent decreases as temperature increases.b) The effects of lattice energies and hydration energies oppose each other in the dissolution of solids in liquids.c) The separation of solute particles from a crystal requires energy.d) The solvation process usually absorbs heat.e) Nonpolar solids do not dissolve appreciably in polar solvents.

KEY

1)a 2)b 3)d 4)e 5)b 6)e 7)d 8)d 9)c 10)a 11)b 12)d 13)d 14)e 15)b 16)a 17)c 18)d 19)e 20)a 21)c 22)d

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1. Identify the CORRECT statement concerning the solubility of various solutes:

a) NaCl would be soluble in the hydrocarbon solvent hexane.b) CaCl2 would be soluble in water.c) KCl would be soluble in the hydrocarbon solvent benzene.d) Hexane and benzene would be immiscible.e) Alcohols and water are generally immiscible.

2. Under what conditions are the molality and molarity of a solution nearly the same?

a) For all solutions where water is the solvent. b) For all solutions which are very dilute. c) For all dilute solutions in which the solvent has a density near 1.0 g/mL. d) For all solutions in which the solvent has a density near 1.0 g/mL.

3. What is the molarity of a solution in which 50.0 mL of chloroform, CHCl3, are placed in a 100.0 mL volumetric flask and the flask is filled to the mark with acetone? The density of pure CHCl3 is 1.483 g/mL.

a) 6.21 Mb) 0.500 Mc) 5.00 Md) 4.188 Me) 0.006 M

4. What is the molality of a urea solution in which 10.0 grams of urea, (NH2)2CO are added to 300.0 mL of water at STP?

a) 0.166 mb) 5.55 x 10-4 mc) 33.3 md) 3.33 x 10-2 me) 0.555 m

5. What is the mole fraction of sulfuric acid in an aqueous solution which is 4.00 M sulfuric acid? The density of the solution is 1.250 g/mL.

a) 0.941b) 0.0672c) 0.0625d) 0.0774

6. A solution has a mole fraction of the nonvolatile solute sucrose of 0.125. The vapor pressure of the pure solvent is 26.0 torr at 25°C. What is the vapor pressure of the solution?

a) 3.25 torrb) 22.75 torrc) 26.0 torrd) 760 torr

7. What would be the freezing point of a 3.00 m aqueous solution of a nonvolatile, nonelectrolyte material? The cryoscopic constant of water is Kf = 1.86 °C/molal.

a) 5.6° Cb) -5.6 °Cc) -3 ° Cd) -1.86 °C

8. A solution was made by dissolving 4.50 grams of a nonvolatile solute in 100.0 grams of acetone. The solution boiled at 56.12 °C. The boiling point of pure acetone is 55.95°C and its Kb = 1.71°C/molal. What is the molecular weight of the unknown solute?

a) 453 g/molb) 492 g/molc) 2.23 x 105 g/mold) 223.5 g/mol

9. Colloids can be distinguished from true solutions by:

a) the dispersing medium. b) the hydrophobic nature of the solute. c) the sizes of the dispersed particles. d) the fact that no settling out occurs in the colloidal dispersion.

10. A colloidal suspension in which a liquid mist is suspended in a gaseous dispersing medium would be called:

a) a gelb) a foamc) an emulsiond) an aerosol

11. Identify the INCORRECT statement below concerning the formation of solutions.

a) The large crystal lattice energy of ionic solids is generally favorable to their solution formation. b) The entropy change upon mixing generally is a favorable factor for the formation of a solution. c) An exothermic heat of solution would favor the formation of a solution relative to an endothermic one. d) The exothermic hydration of ions in water is generally a favorable factor to solution formation. e) One may generally say that "like dissolves like."

12. Identify the INCORRECT statement below:

a) An endothermic heat of solution for NaCl(aq) implies that its solubility would increase as T increases. b) Henry's Law relates the pressure of a gas above a liquid to the concentration of dissolved gas. c) The solubility of a substance always increases when the temperature of solution is increased. d) Raoult's Law relates the vapor pressure of a liquid to its mole fraction in the solution phase.

e) A colligative property is a physical property of a solution that depends on the number of solute particles, and not their identity.

13. Another name for a true solution is:

a) heterogeneous mixtureb) homogeneous mixturec) suspensiond) colloid

14. Which factor below would generally favor solution formation?

a) nonpolar solventsb) endothermic heat of solutionc) large crystal lattice energy of soluted) entropy of mixing

15. Which substance would have the highest solubility in hexane, C6H14?

a) NaClb) H2Oc) S8

d) NH3

16. A 10.0% aqueous solution of glucose C6H12O6 by mass used in intravenous feeding would have what molality?

a) 0.617 mol/kgb) 0.555 mol/kgc) 0.100 mol/kgd) 0.111 mol/kg

17. What additional piece of information would be required to calculate the molarity of the solution in Problem #16?

a) mole fraction of the soluteb) molecular weight of solventc) mass density of the solutiond) heat capacity of the solution

18. A colloidal suspension in which tiny droplets of oil are suspended in soapy water (when doing dishes, etc.) is called:

a) a gelb) an aerosol

c) a foamd) an emulsion

19. Oil is solubilized in soapy water by the:

a) formation of micellesb) Tyndall effectc) reverse osmosis processd) eutrophication process

20. Suppose 3.6 grams of an unknown solute is dissolved in 100 grams of liquid benzene and the freezing point of the liquid is lowered by 2.56° C. Which of the following substances is this unknown substance most likely to be? The cryoscopic constant of benzene is 5.12° C/molal.

a) C6H14

b) C5H12

c) H2Od) NaCl

21. Identify the INCORRECT statement below:

a) Henry's Law relates the pressure of a gas above a liquid to the concentration of dissolved gas. b) The solubility of a substance generally increases when the temperature of solution is increased. c) A colligative property is a physical property of a solution that depends on the number of solute particles, and not their identity. d) An endothermic heat of solution for NaCl(aq) implies that its solubility would increase as T increases. e) Raoult's Law relates the vapor pressure of a liquid to its mole fraction in the solution phase.

22. Colloids can be distinguished from true solutions by:

a) the hydrophobic nature of the soluteb) the dispersing mediumc) the fact that no settling out occurs in the colloidal dispersiond) the sizes of the dispersed particles

KEY

1)b 2)c 3)a 4)e 5)d 6)b 7)b 8)a 9)c 10)d 11)a 12)c 13)b 14)d 15)c 16)a 17)c 18)d 19)a 20)b 21)b 22)d

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