CHE 161
ACS REVIEW
CH 8-10
1. Which of the following statements is incorrect?
a)
b)
c)
d)
e)
Ionic bonding results from the transfer of electrons from one atom to another.
Dipole moments result from the unequal distribution of electrons in a molecule.
The electrons in a polar bond are found nearer to the more electronegative element.
A molecule with very polar bonds can be nonpolar.
Linear molecules cannot have a net dipole moment.
2. Choose the compound with the most ionic bond.
a) LiCl
b) KF
c) NaCl
d) LiF
e) KCl
3. Which of the following bonds is least polar?
a)
b)
c)
d)
e)
C—O
H—C
S—Cl
Br—Br
They are all nonpolar.
4. Which of the following groups contains no ionic compounds?
a)
b)
c)
d)
e)
HCN, NO2, Ca(NO3)2
PCl5, LiBr, Zn(OH)2
KOH, CCl4, SF4
NaH, CaF2, NaNH2
CH2O, H2S, NH3
5. How many of the following molecules possess dipole moments?
I.
a) 1
b) 2
c) 3
d) 4
e)5
BH3, CH4, PCl5, H2O, HF, H2
6. Choose the statement that best describes the PbCl4 molecule in the gas phase.
a)
b)
c)
d)
e)
The bond angles are all about 109.
The molecule is polar.
The molecule has a dipole moment.
The bonds are nonpolar.
a, b, and c
7. Which of these is an isoelectronic series?
a) Na+, K+, Rb+, Cs+
b) K+, Ca2+, Ar, S2c) Na+, Mg2+, S2-, Cld) Li, Be, B, C
e) none of these (a-d)
8. Which of the following ionic compounds has the smallest lattice energy, i.e., the lattice energy least
favorable to a stable lattice?
a)
b)
c)
d)
e)
LiF
CsI
NaCl
BaO
MgO
9. Calculate the lattice energy for LiF(s) given the following:
I.
sublimation energy for Li(s)
+166 kJ/mol
II.
Hf for F(g)
III.
first ionization energy of Li(g) +520. kJ/mol
IV.
electron affinity of F(g) –328 kJ/mol
V.
enthalpy of formation of LiF(s) –617 kJ/mol
+77 kJ/mol
a) 285 kJ/mol
b) –650. kJ/mol
c) 800. kJ/mol
d) –1047 kJ/mol
e)None of these
10. Which of the following pairs is isoelectronic?
a)
b)
c)
d)
e)
Li+ and K+
Na+ and Ne
I– and Cl–
S2– and Ne
Al3+ and B3+
11. The first electron affinity value for oxygen is _______ and the second electron affinity value is ________.
a)
b)
c)
d)
e)
unfavorable (endothermic), favorable (exothermic)
unfavorable (endothermic), unfavorable (endothermic)
favorable (exothermic), favorable (exothermic)
favorable (exothermic), unfavorable (endothermic)
More information is needed.
12. Which of the following molecules exhibits the greatest bond energy?
a)
b)
c)
d)
e)
F2
Cl2
Br2
I2
all the same
13. As the number of bonds between two carbon atoms increases, which one of the following decreases?
a)
b)
c)
d)
e)
number of electrons between the carbon atoms
bond energy
bond length
all of these
none of these
14. Which of the following has the smallest radius?
a)
b)
c)
d)
e)
FNe
O2Mg2+
Na+
15. Which of the following species is best described by drawing resonance structures?
a) PH3
b) NH4+
c) O3
d) SO3e) HCN
16. Given the following bond energies
I.
C–C
347 kJ/mol
II.
C=C
614 kJ/mol
III.
C–O
358 kJ/mol
IV.
C=O
799 kJ/mol
V.
C–H
413 kJ/mol
VI.
O–H
463 kJ/mol
VII.
O–O
146 kJ/mol
17. estimate H for the reaction H2O2 + CH3OH  H2CO + 2H2O.
a)
b)
c)
d)
e)
–345 kJ
–199 kJ
–105 kJ
+199 kJ
+345 kJ
18. As indicated by Lewis structures, which of the following would probably not exist as a stable
molecule?
a) CH3OH
b) CH2O
c) CH3O
d) C2H2
e) C3H4
19. Select the best Lewis structure for acetone, CH3COCH3.
H
H
a)
b)
C O C H
H
a)
H
b)
C
H
H
H
O
H
C
C
C H
H
H
H
c)
c)
H C C O H C H
H
H
H
d) d)
H H C C O C H
H
H
H H H
H C C C O
e)
e)
H H
20. According to the VSEPR model, the arrangement of electron pairs around NH3 and CH4 are
a)
b)
different because in each case there are a different number of atoms around the central atom.
different because in each case there are a different number of electron pairs around the central
atom.
c) the same because both nitrogen and carbon are both in the second period.
d) the same because in each case there are the same number of electron pairs around the central
atom.
e) different or the same, depending on the conditions leading to maximum repulsion.
21. In the cyanide ion (CN–), the nitrogen has a formal charge of
a)
b)
c)
d)
e)
-2
-1
0
2
2
22. Which of the following is not a valid resonance structure for N3–?
a)
b)
c)
N
N
N
N
N
N
N
N
N
N
N
N
-
a)
b)
c)
-
d) d)
e)
all are correct
23. What type of structure does the XeOF2 molecule have?
a) pyramidal
b) tetrahedral
c) T-shaped
d) trigonal planar
24. According to VSEPR theory, which of the following species has a square planar molecular structure?
a) TeBr4
b) BrF3
c) IF5
d) XeF4
e) SCl2
25. The hybridization of the phosphorus atom in the cation PH2+ is:
a)
b)
c)
d)
e)
sp2
sp3
dsp
sp
none of these
26. The hybridization of the central atom in XeF5+ is:
a)
b)
c)
d)
e)
sp
sp2
sp3
dsp3
d2sp3
27. Which of these statements about benzene is true?
a)
b)
c)
d)
e)
All carbon atoms in benzene are sp3 hybridized.
Benzene contains only  bonds between C atoms.
The bond order of each C—C bond in benzene is 1.5.
Benzene is an example of a molecule that displays ionic bonding.
All of these statements are false.
28. What is the bond order of Ne2?
a)
b)
c)
d)
e)
0
1/2
1
1 1/2
2
29. Which of the following statements is false?
a)
C2 is paramagnetic.
b)
C2 is diamagnetic.
c)
The carbon-carbon bond in C22– is stronger than the one in CH3CH3.
d) The carbon-carbon bond in C22– is shorter than the one in CH3CH3.
e)
Two of the above.
30. The configuration (2s)2(2s*)2(2py)1 (2px)1
31. is the molecular orbital description for the ground state of
a)
Li2+
b)
Be2
c)
B2
d) B22–
e)
C2
32. Which of the following electron distributions among the molecular orbitals best describes the NO
molecule?
I.
b)
c)
d)
e)
f)
a)
b)
c)
d)
e)
2s 2s* 2py=2px
2
2
2
2
2
2
2
2
2
2
2pz
2py*=2px*
2pz*
4
4
4
4
4
2
2
1
2
2
4
4
3
2
1
2
1
0
0
0
33. The following statements concern molecules that require resonance. Which is true?
a) The pi bonding is most clearly delocalized.
b) The sigma bonding is most clearly delocalized.
c) Both the sigma and pi bonding are delocalized.
d) The benzene molecule is best described by the MO theory.
e) The benzene molecule is best described by the localized electron model.
34. Consider the benzene molecule. Which of the following statements about the molecule is false?
All six C  C bonds are known to be equivalent.
Each carbon atom is sp2 hybridized.
The localized electron model must invoke resonance to account for the six equal
C  C bonds.
d) It has delocalized pi bonding in the molecule.
a)
b)
c)
e) The pi bonds of carbon involve sp2 orbitals.
35. Which of the following is most likely to be a solid at room temperature?
a)
b)
c)
d)
e)
Na2S
HF
NH3
N2
H2O
36. On a relative basis, the weaker the intermolecular forces in a substance,
a)
b)
c)
d)
e)
the greater its heat of vaporization.
the more it deviates from ideal gas behavior.
the greater its vapor pressure at a particular temperature.
the higher its melting point.
none of these
37. 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
38. The elements of group 5A, the nitrogen family, form compounds with hydrogen having the boiling
points listed below:
I.
SbH3 –17C, AsH3 –55C, PH3 –87C, NH3 –33C
39. The first three elements illustrate a trend where the boiling point decreases as the mass decreases;
however, ammonia (NH3) does not follow the trend because of
a)
b)
c)
d)
e)
dipole-dipole attraction.
metallic bonding.
hydrogen bonding.
London dispersion forces.
ionic bonding.
40. Which of the following substances would you expect to have the lowest boiling point?
a)
b)
diamond
methane, CH4
c)
sodium nitrate, NaNO3
d) glycerine, C3H5(OH)3
e)
copper
41. The number of Pb atoms per unit cell.
a)
b)
c)
d)
3
4
10
12
e) 14
42. Generally the vapor pressure of a liquid is related to
I.
II.
III.
IV.
the amount of liquid
atmospheric pressure
temperature
intermolecular forces
a) I, III
b) II, III, IV
c) I, III, IV
d) III, IV
e)all information is needed
43. 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)
b)
c)
d)
e)
5
4
3
2
1
44. Which one of the following statements about solid Cu (face-centered cubic unit cell) is incorrect?
a)
b)
c)
d)
e)
It will conduct electricity.
There are two atoms per unit cell.
The number of atoms surrounding each Cu atom is 12.
The solid has a cubic closest-packed structure.
The length of a face diagonal is four times the Cu radius.
45. At normal atmospheric pressure and a temperature of 0°C, which phase(s) of H2O can exist?
a) ice and water
b) ice and water vapor
c) water only
d) water vapor only
e) ice only
46. The bonds between hydrogen and oxygen in a water molecule can be characterized as __________.
a)
b)
c)
d)
e)
hydrogen bonds
London dispersion forces
intermolecular forces
intramolecular forces
dispersion forces
47. 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)
r = ( 2/4) E
c)
r = ( 3/4) E
d) r = 2E
e)
r = 4E
48. 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
49. 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)
b)
c)
Helium and xenon form highly polar molecules.
As the molecular weight of the noble gas increases, the freezing point decreases.
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
50. Which of the following processes must exist in equilibrium with the evaporation process when a
measurement of vapor pressure is made?
a)
b)
c)
d)
e)
fusion
vaporization
sublimation
boiling
condensation
51. 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)
b)
c)
d)
e)
0%
26.0%
32.0%
68.0%
none of these
52. A metal crystallizes with a face-centered cubic lattice. The edge of the unit cell is 408 pm. The diameter
of the metal atom is:
a)
b)
c)
d)
e)
144 pm
204 pm
288 pm
408 pm
none of these
53. 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)
54. A crystal of NaCl is
a)
b)
c)
d)
e)
soft, low melting, a good electrical conductor.
hard, high melting, a good electrical conductor.
soft, low melting, a poor electrical conductor.
hard, high melting, a poor electrical conductor.
soft, high melting, a poor electrical conductor.
55. What is responsible for capillary action, a property of liquids?
a)
b)
c)
d)
e)
surface tension
cohesive forces
adhesive forces
viscosity
two of these
56. When a nonpolar liquid displays a convex meniscus, which of the following explains this behavior?
a)
b)
c)
d)
e)
It has a low surface tension, and therefore clings to the glass.
The cohesive forces are stronger than the adhesive forces toward the glass.
The adhesive forces toward the glass are stronger than the cohesive forces.
The liquid’s viscosity is low.
none of these
57. Given below are the temperatures at which two different liquid compounds with the same empirical
formula have a vapor pressure of 400 torr.
II.
III.
1. Compound
T (C)
dimethyl ether, CH3–O–CH3 –37.8
ethanol, CH3CH2OH 63.5
58. Which of the following statements (a–d) is false?
a)
b)
c)
Increasing the temperature will increase the vapor pressure of both liquids.
Intermolecular attractive forces are stronger in (liquid) ethanol than in (liquid) dimethyl ether.
The normal boiling point of dimethyl ether will be higher than the normal boiling point of
ethanol.
d) The reason that the temperature at which the vapor pressure is 400 torr is higher for ethanol
(than for dimethyl ether) is that there is strong hydrogen bonding in ethanol.
e) None of these is false.
59. In which of the following processes will energy be evolved as heat?
a)
b)
c)
d)
e)
sublimation
crystallization
vaporization
melting
none of these
60. The vapor pressure of water at 100.0C is
a)
b)
c)
d)
e)
85 torr
760 torr
175 torr
1 torr
More information is needed.
61. The triple point of iodine is at 90 torr and 115C. This means that liquid I2
a)
is more dense than I2(s).
b)
c)
d)
e)
cannot exist above 115C.
cannot exist at 1 atmosphere pressure.
cannot have a vapor pressure less than 90 torr.
can exist at pressure of 10 torr.
1.
62.
1.5
1.0
P(atm)
63.
0.5
a.
0
100
T (K)
200
300
64. Above is a phase diagram for compound X.
You wish to purify a sample of X which was collected at P = 1.0 atm and T = 100 by subliming it. In
order to sublime the sample, you should:
a)
b)
c)
d)
e)
increase P to 1.5 atm and then increase T to 300 K.
increase T to 300 K, keeping P = 1.0 atm.
lower P to 0.5 atm and then increase T to 200 K.
increase T to 300 K and then lower P to 0.5 atm.
abandon the attempt to sublime X.
i.
65.
B
A
P (atm )
66.
67.
C
E
F
D
T
68. Based on the phase diagram shown above, which of the following statements are correct?
I.
II.
III.
IV.
V.
Sublimation occurs at a point in the transformation that occurs along a straight line
from point A to point F.
C and E represent points where the gas and liquid phases are in equilibrium.
Hvap can be measured at point B.
Molecules at point D have a greater average kinetic energy than those at point F.
The temperature at point E is called the critical temperature of the compound.
a) II, V
b) I, III, IV
c) I, II, III
d) II, IV, V
e)I, II, IV
69. The density of the solid phase of a substance is 0.90 g/cm3 and the density of the liquid phase is 1.0
g/cm3. A large increase in pressure will
a)
b)
c)
d)
lower the freezing point.
raise the freezing point.
lower the boiling point.
raise the triple point.
e)
lower the triple point
70. The heat of combustion of bituminous coal is 2.50  104 J/g. What quantity of the coal is required to
produce the energy to convert 109.5 pounds of ice at 0.00C to steam at 100.C?
a)
b)
c)
d)
e)
5.96 kg
0.660 kg
0.828 kg
4.48 kg
1.49 kg