Chapter 10 1 Hydrogen bonds account for which of the following observation

Chapter 10: Liquids and Solids

1. Order the intermolecular forces (dipole-dipole, London dispersion, ionic, and hydrogen-

bonding) from weakest to strongest .

A)

dipole-dipole, London dispersion, ionic, and hydrogen-bonding

B)

London dispersion, dipole-dipole, hydrogen-bonding, and ionic

C)

hydrogen-bonding, dipole-dipole, London dispersion, and ionic

D)

dipole-dipole, ionic, London dispersion, and hydrogen-bonding

E)

London dispersion, ionic, dipole-dipole, and hydrogen-bonding

2. Hydrogen bonds account for which of the following observation?

A)

Hydrogen naturally exists as a diatomic molecule.

B)

Hydrogen is easily combustible with oxygen.

C)

Water molecules are bent or “V-shaped.”

D)

Air is more dense than hydrogen gas.

E)

For its molar mass, water has a high boiling point.

3. Which of the following would you expect to have the highest boiling point?

A)

F2

B)

Cl2

C)

Br2

D)

I2

E)

All of the above have the same boiling point.

4. Which of the following should have the lowest boiling point?

A)

Na2S

B)

HF

C)

NH3

D)

N2

E)

H2O

5. Which of the species below would you expect to show the least hydrogen bonding?

A)

NH3

B)

H2O

C)

HF

D)

CH4

E)

all the same

6. The molecules in a sample of solid SO2 are attracted to each other by a combination of

A)

London forces and H-bonding

B)

H-bonding and ionic bonding

C)

covalent bonding and dipole-dipole interactions

D)

London forces and dipole-dipole interactions

E)

none of these

7. In which of the following groups of substances would dispersion forces be the only

significant factors in determining boiling points?

I.

Cl2

II.

HF

III.

Ne

IV.

KNO2

V.

CCl4

A)

I, III, V

B)

I, II, III

C)

II, IV

D)

II, V

E)

III, IV, V

8. The elements of group 5A, the nitrogen family, form compounds with hydrogen having the

boiling points listed below:

SbH3 –17°C, AsH3 –55°C, PH3 –87°C, NH3 –33°C

The first three compounds illustrate a trend where the boiling point decreases as the mass

decreases; however, ammonia (NH3) does not follow the trend because of

A)

dipole-dipole attraction

B)

metallic bonding

C)

hydrogen bonding

D)

London dispersion forces

E)

ionic bonding

9. Which substance involves no bonding forces except London dispersion forces?

A)

NaCl(l)

B)

HF(l)

C)

N2(s)

D)

H2O(l)

E)

K(s)

10. In general, the density of a compound as a gas is closer in value to that of the compound as a

liquid than the density of the compound as a liquid is in value to that of the compound as a

solid.

11. Second row hydrides generally have higher than expected boiling points for their position

on the periodic table.

12. The bonds between hydrogen and oxygen within a water molecule can be characterized as

__________.

A)

hydrogen bonds

B)

London dispersion forces

C)

intermolecular forces

D)

intramolecular forces

E)

dispersion forces

13. When a water molecule forms a hydrogen bond with another water molecule, which atoms

are involved in the interaction?

A)

a hydrogen from one molecule and a hydrogen from the other molecule

B)

a hydrogen from one molecule and an oxygen from the other molecule

C)

an oxygen from one molecule and an oxygen from the other molecule

D)

an oxygen and a hydrogen from the same molecule

E)

two hydrogens from one molecule and one hydrogen from the other molecule

14. Which of the following is the correct order of boiling points for KNO3, CH3OH, C2H6, Ne?

A)

Ne < CH3OH < C2H6 < KNO3

B)

KNO3 < CH3OH < C2H6 < Ne

C)

Ne < C2H6 < KNO3 < CH3OH

D)

Ne < C2H6 < CH3OH < KNO3

E)

C2H6 < Ne < CH3OH < KNO3

Consider the representations below to answer the next three questions.

(I)

(II)

(III)

15. How many of the following statements are correct concerning drawing I?

I.

Each molecule induces a dipole onto the next molecule in close

proximity.

II.

The phenomenon shown is relatively weak and short-lived.

III.

C8H18 contains this type of interaction.

IV.

The forces that exist in this example are London dispersion forces.

A)

0

B)

1

C)

2

D)

3

E)

4

16. Which drawing best represents the interactions in a sample of HF?

A)

I

B)

II

C)

III

D)

I, II

E)

all of the above

17. Which of the following statements are incorrect concerning drawing III?

A)

Electrostatic interactions exist between the molecules.

B)

The molecules find the best compromise between attraction and repulsion.

C)

These molecules exhibit ionic bonding.

D)

OCS exhibits this type of interaction.

E)

Two of the above statements are incorrect.

18. The freezing point of helium is –270°C. The freezing point of xenon is –112°C. Both of

these are in the noble gas family. Which of the following statements is supported by these

data?

A)

Helium and xenon form highly polar molecules.

B)

As the molecular weight of the noble gas increases, the freezing point decreases.

C)

The London dispersion forces between the helium molecules are greater than the

London dispersion between the xenon molecules.

D)

The London dispersion forces between the helium molecules are less than the

London dispersion forces between the xenon molecules.

E)

None of these.

19. Which best explains the following trend?

Element

b.p. (K)

He

4

Ne

25

Ar

95

Kr

125

Xe

170

A)

London dispersion forces

B)

dipole-dipole interaction

C)

hydrogen bonding

D)

Le Chatelier’s principle

E)

none of these

20. Intermolecular forces are weaker than intramolecular bonds.

21. Hydrogen bonding is a type of London dispersion force.

22. Methane (CH4) exhibits stronger hydrogen bond interactions than ammonia (NH3).

23. Which of the following compounds has the lowest viscosity?

A)

CCl4(l)

B)

N2(g)

C)

H2O(l)

D)

CH3-(CH2)25–CH3(l)

E)

HCl(g)

24. Which of the following statements about liquids is true?

A)

Droplet formation occurs because of the higher stability associated with increased

surface area.

B)

Substances that can form hydrogen bonds will display lower melting points than

predicted from periodic trends.

C)

London dispersion forces arise from a distortion of the electron clouds within a

molecule or atom.

D)

Liquid rise within a capillary tube because of the small size lowers the effective

atmospheric pressure over the surface of the liquid.

E)

The boiling point of a solution is dependent solely on the atmospheric pressure

over the solution.

25. What is responsible for capillary action, a property of liquids?

A)

surface tension

B)

cohesive forces

C)

adhesive forces

D)

viscosity

E)

two of these

26. When a nonpolar liquid displays a convex meniscus, which of the following explains this

behavior?

A)

It has a low surface tension, and therefore clings to the glass.

B)

The cohesive forces are stronger than the adhesive forces to the glass.

C)

The adhesive forces to the glass are stronger than the cohesive forces.

D)

The liquid’s viscosity is low.

E)

None of these.

27. Liquids with large intermolecular forces tend to have high surface tension.

28. The unit cell in this two-dimensional crystal contains __________ Xs and __________ Os.

X

O

X

O

X

O

A)

1,1

B)

2,1

C)

1,2

D)

4,1

E)

1,4

29. Which of the following is paired incorrectly?

A)

crystalline solids—highly regular arrangement of their components

B)

amorphous solids—considerable disorder in their structures

C)

unit cell—the smallest repeating unit of the lattice

D)

gold metal—simple cubic unit cell

E)

glass—amorphous solid

30. Table salt and table sugar are both crystalline solids.

31. Atomic solids generally have low melting points.

32. A crystal was analyzed with x-rays having 1.57 Å wavelength. A reflection was produced at

 = 21.9°. Assuming n = 1, what is the distance between the layers of atoms in the crystal?

A)

8.42 Å

B)

4.21 Å

C)

0.475 Å

D)

0.846 Å

E)

2.10 Å

33. A crystal was analyzed with x-rays having 2.33 Å wavelength. The angle of first-order

diffraction (n = 1) was 19.2°. What would be the angle for second-order diffraction (n = 2)?

A)

38.4 Å

B)

41.1 Å

C)

9.46 Å

D)

14.2 Å

E)

4.72 Å

The molar volume of a certain form of solid lead is 18 cm3/mol. Assuming cubic closest

packed structure, determine the following:

34. The number of Pb atoms per unit cell.

A)

1

B)

2

C)

4

D)

6

E)

10

35. The volume of a single cell.

A)

1.20  102 pm3

B)

1.20  104 pm3

C)

1.20  106 pm3

D)

1.20  108 pm3

E)

none of these

36. The radius of a Pb atom.

A)

1.74 pm

B)

17.4 pm

C)

174 pm

D)

1740 pm

E)

none of these

37. Cubic closest packing is another name for _____________.

A)

simple cubic packing

B)

body-centered cubic packing

C)

face-centered cubic packing

D)

hexagonal closest packing

E)

more than one of these

38. Which one of the following statements about solid Cu (face-centered cubic unit cell) is

incorrect?

A)

It will conduct electricity.

B)

There are two atoms per unit cell.

C)

The number of atoms surrounding each Cu atom is 12.

D)

The solid has a cubic closest-packed structure.

E)

The length of a face diagonal is four times the Cu radius.

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

unit cells?

A)

1

B)

4

C)

8

D)

2

E)

6

40. Which of the following statements is (are) false?

I.

The layering in a hexagonal closest-packed structure is aba.

II.

A body-centered cubic unit cell has four atoms per unit cell.

III.

For unit cells having the same edge length, a simple cubic structure would have

a smaller density than a body-centered cube.

IV.

Atoms in a solid consisting of only one element would have six nearest

neighbors if the crystal structure were a simple cubic array.

A)

I

B)

II

C)

II, III

D)

I, IV

E)

II, III, IV

41. Aluminum metal crystallizes in a face-centered cubic structure. The relationship between

the radius of an Al atom (r) and the length of an edge of the unit cell (E) is:

A)

r = E/2

B)

C)

D)

r = 2E

E)

42. Chromium metal crystallizes as a body-centered cubic lattice. If the atomic radius of Cr is

1.25 angstroms, what is the density of Cr metal in g/cm3?

A)

5.52

B)

7.18

C)

14.4

D)

2.76

E)

3.59

43. You are given a small bar of an unknown metal, M. You find the density of the metal to be

10.5 g/cm3. An X-ray diffraction experiment measures the edge of the unit cell as 409 pm.

Assuming that the metal crystallizes in a face-centered cubic lattice, what is M most likely

to be?

A)

Ag

B)

Rh

C)

Pt

D)

Pb

E)

none of these

44. Silver chloride crystallizes with the sodium chloride (rock salt) structure. The length of a

unit cell edge is 555 pm. What is the density of AgCl?

A)

5.57 g/cm3

B)

4.19 g/cm3

C)

2.79 g/cm3

D)

2.10 g/cm3

E)

1.39 g/cm3

45. A metal crystallizes in a body-centered unit cell with an edge length of 2.00  102 pm.

Assume the atoms in the cell touch along the cube diagonal. The percentage of empty

volume in the unit cell will be:

A)

0%

B)

26.0%

C)

32.0%

D)

68.0%

E)

none of these

46. A metal crystallizes with a face-centered cubic lattice. The edge of the unit cell is 395 pm.

The diameter of the metal atom is:

A)

140 pm

B)

198 pm

C)

279 pm

D)

395 pm

E)

none of these

47. If equal, rigid spheres are arranged in a simple cubic lattice in the usual way (i.e., in such a

way that they touch each other), what fraction of the corresponding solid will be empty

space? [The volume of a sphere is (4/3)r3, with  = 3.14.]

A)

0.52

B)

0.32

C)

0.68

D)

0.48

E)

none of these

48. Which substance can be described as cations bonded together by mobile electrons?

A)

Ag(s)

B)

S8(s)

C)

Kr(l)

D)

KCl(s)

E)

HCl(l)

49. Steel is considered to be a(n) __________.

A)

interstitial alloy

B)

ionic solid

C)

molecular solid

D)

substitutional alloy

E)

two of these

50. Which of the following statements about steel is false?

A)

It contains carbon atoms in the holes of its iron crystals.

B)

The presence of carbon-iron bonds in the alloy make steel harder and stronger than

pure iron.

C)

Pure iron is relatively soft and ductile because it lacks directional bonding.

D)

The amount of carbon directly affects the properties of steel.

E)

All of these are true.

51. What is the simplest formula of a solid containing A, B, and C atoms in a cubic lattice in

which the A atoms occupy the corners, the B atoms the body-center position, and the C

atoms the faces of the unit cell?

A)

ABC

B)

ABC3

C)

ABC6

D)

A8BC6

E)

A4BC3

52. A solid material consists of an array of A atoms with Z atoms located in the spaces in the

lattice. This solid would be classified as

A)

an amalgam

B)

an interstitial alloy

C)

a substitutional alloy

D)

a semiconductor

E)

ceramic

53. The net number of spheres in the face-centered cubic unit cell is 4.

54. Steel is a substitutional alloy.

55. Which of the following statements is true about p-type silicon?

A)

It is produced by doping Si with P or As.

B)

Protons are the mobile charge carriers.

C)

It does not conduct electricity as well as pure Si.

D)

All are true.

E)

None is true.

56. Doping Se with B would produce a(n) __________ semiconductor with __________

conductivity compared to pure Se.

A)

p-type, increased

B)

n-type, decreased

C)

n-type, increased

D)

p-type, decreased

E)

intrinsic, identical

57. A material is made from Al, Ga, and As. The mole fraction of each element is 0.25, 0.26,

and 0.49, respectively. This material would be

A)

a metallic conductor because Al is present

B)

an insulator

C)

a p-type semiconductor

D)

an n-type semiconductor

E)

none of the above

58. Which of the compounds below is an example of a network solid?

A)

S8(s)

B)

SiO2(s)

C)

MgO(s)

D)

NaCl(s)

E)

C25H52(s)

59. Which of the compounds below is not an example of a molecular solid?

A)

I2(s)

B)

SiO2(s)

C)

CO2(s)

D)

H2O(s)

E)

C25H52(s)

60. Ice is a molecular solid.

61. Which of these statements is incorrect?

A)

Molecular solids have high melting points.

B)

The binding forces in a molecular solid include London dispersion forces.

C)

Ionic solids have high melting points.

D)

Ionic solids are insulators.

E)

All of the statements (A-D) are correct.

62. At room temperature, CsF is expected to be

A)

a gas

B)

a conducting solid

C)

a liquid

D)

a brittle solid

E)

a soft solid

63. A solid crystal of NaCl is

A)

soft, low melting, a good electrical conductor

B)

hard, high melting, a good electrical conductor

C)

soft, low melting, a poor electrical conductor

D)

hard, high melting, a poor electrical conductor

E)

soft, high melting, a poor electrical conductor

64. Solid MgO has the same crystal structure as NaCl. How many oxide ions surround each

Mg2+ ion as nearest neighbors in MgO?

A)

4

B)

6

C)

8

D)

12

E)

none of these

65. Which of the following has the highest melting temperature?

A)

H2O

B)

CO2

C)

S8

D)

MgF2

E)

P4

66. A certain solid substance that is very hard, has a high melting point, and is nonconducting

unless melted is most likely to be:

A)

I2

B)

NaCl

C)

CO2

D)

H2O

E)

Cu

67. Which of these statements is false?

A)

Diamond is a covalent crystal.

B)

The size of the unit cell of Li and Cs is the same.

C)

Molecular crystals usually have low melting points.

D)

Metallic crystals are usually good electrical conductors.

E)

None of the statements is false.

68. An ionic crystalline solid, MX2, has a cubic unit cell. Which of the following arrangements

of the ions is consistent with the stoichiometry of the compound?

A)

M2+ ions at the corners and at each face, 8 X– ions at the tetrahedral centers

B)

M2+ ions at each face, X– ions at the corners

C)

M2+ ions at the corners, X– ions at the faces, and 2 X– ions at the tetrahedralcenters

D)

4 M2+ ions at the body centers, X– ions at the corners and at the faces

E)

M2+ ions at the corners and at the faces, 4 X– ions at the octahedral centers

69. Lithium chloride crystallizes in a face-centered cubic structure. The unit cell length is

5.14  10–8 cm. The chloride ions are touching each other along the face diagonal of the unit

cell. The lithium ions fit into the holes between the chloride ions. What is the mass of LiCl

in a unit cell?

A)

7.04  10–23 g

B)

1.41  10–22 g

C)

2.82  10–22 g

D)

4.22  10–22 g

E)

5.63  10–22 g

70. How would you expect the melting point of C[$X]4 to compare to that of [$I][$X]?

A)

It should be lower because [$I][$X] forms an extended ionic crystal lattice,

whereas C[$X]4 is a covalently-bonded small molecule.

B)

It should be similar since they are both ionic solids.

C)

It should be higher because the bonds are stronger due to the higher charge on C

(+4).

D)

It should be higher because C[$X]4 is larger than [$I][$X].

E)

It is not possible to say anything about their melting points without more

information.

71. In the unit cell of sphalerite, Zn2+ ions occupy half the tetrahedral holes in a face-centered

cubic lattice of S2– ions. The number of formula units of ZnS in the unit cell is:

A)

6

B)

4

C)

3

D)

2

E)

1

72. The unit cell in a certain lattice consists of a cube formed by an anion at each corner, an

anion in the center, and a cation at the center of each face. The unit cell contains a net:

A)

5 anions and 6 cations

B)

5 anions and 3 cations

C)

2 anions and 3 cations

D)

3 anions and 4 cations

E)

2 anions and 2 cations

73. Which of the following statements about the closest packing of spheres in binary ionic

solids is false?