CHEMISTRY 163
MIDTERM #1 CONCEPTUAL REVIEW
1. Which of the following is true regarding the attractive force that holds sodium chloride in the
solid state?
I.
II.
III.
IV.
It is electrostatic.
It is termed ionic bonding.
It depends on the distance between the sodium and chloride.
It only operates between adjacent sodium and chloride.
2. e two types of closest-packed lattices are ________
a.
b.
c.
d.
e.
cubic closest-packed and face-centered cubic.
cubic closest-packed and hexagonal closest-packed.
cubic closest-packed and random closest-packed.
cubic closest-packed and pyramidal closest-packed.
simple cubic and hexagonal closest-packed.
3. The closest packing of spheres (such as oranges, cannonballs, or atoms) has the spheres ________
a.
b.
c.
d.
e.
arranged in layers with each sphere surrounded by 4 other spheres in the layer.
arranged in layers with each sphere surrounded by 3 other spheres in the layer.
arranged in a square pattern with a sphere at each corner and one in the center of the
square.
arranged in a square pattern with a sphere at each corner of the square.
arranged in layers with each sphere surrounded by 6 other spheres in the layer.
4. A hexagonal closest-packed structure has hexagonally arranged layers of atoms stacking in the
series ________
a.
b.
c.
ababab.
abcabcabc.
abcbabcbabcba.
d.
e.
abacabacaba.
aaaaaa.
5. The face-centered cubic structure is also known as ________
a.
b.
c.
d.
e.
cubic closest-packed.
hexagonal closest-packed.
square closest-packed.
spherical closest-packed.
none of the above, as it is not a closest-packed pattern.
6. Which of the following unit cells has the lowest packing efficiency?
a.
b.
c.
d.
e.
simple cubic
face-centered cubic
body-centered cubic
both face-centered and body-centered cubic
Simple, face-centered, and body-centered cubic all have the same packing efficiency.
7. How many nearest neighbor atoms are there around each atom in a simple cubic unit cell?
a.
b.
c.
4
6
8
d.
e.
10
12
8. Which of the following refers to an alloy in which the composition is variable and the elements
have comparable radii?
a.
b.
intermetallic
interstitial
d.
e.
substitutional
homogeneous
9. A tetrahedral hole in a crystal lattice is defined as ________
a.
b.
c.
d.
e.
one-half of an octahedral hole.
the space between any number of atoms having tetrahedral edges.
the space between a cage of sp3 hybridized atoms, such as in diamond.
the space between a cluster of four adjacent atoms arranged in a tetrahedron.
a large hole having four flat sides arranged in a tetrahedral shape.
10. The bonding in solid-state metals can be described as ________
a.
b.
c.
nonexistent.
a covalent network.
an electron sea.
d.
e.
highly directional.
ionic.
11. Electrical and thermal conductivity in metals ________
a.
b.
c.
d.
e.
is explained by a dipolar coupling model.
is explained by band theory.
is explained by matrix isolation techniques.
is explained by temporary ionization.
is a function of the level of contamination by excess electrons.
12. Which statement regarding the electronic structure of solids is not correct?
a.
b.
c.
d.
e.
The band theory of solids is like molecular orbital theory in that the electronic wave
function is delocalized to some extent over all the constituent atoms.
In solids that are electrical insulators, there is a large gap between a filled valence band
and a vacant conduction band.
In semiconductors, the gap between the valence band and conduction band is small, so a
few electrons have sufficient thermal energy to be found in the conduction band.
n- and p-type semiconductors can be produced by doping a semimetal with an element
from a different group.
Germanium doped with arsenic is a p-type semiconductor.
13. When silicon is doped with gallium, electrical conduction increases because ________
a.
b.
c.
d.
e.
gallium has fewer valence electrons than silicon, so holes are created in the valence band
of silicon.
gallium has more valence electrons than silicon, so electrons are added to the conduction
band of silicon.
gallium causes electrons to be transferred from the valence band of silicon to the
conduction band of silicon.
gallium causes electrons to be transferred from the conduction band of silicon to the
valence band of silicon.
gallium is a better conductor of electricity than silicon.
14. A face-centered cubic unit cell has a(n) ________ in its center.
a.
b.
c.
tetrahedral hole d.
octahedral hole e.
atom
square planar hole
cubic hole
15. If half of the tetrahedral holes in a face-centered cubic unit cell are filled, what must be the
stoichiometry of the ionic compound, written as nonhole sites:hole sites in lowest terms?
a.
b.
c.
2:1
1:1
1:2
d.
e.
4:1
2:3
16. Different structural forms of the elements are called ________
a.
b.
c.
polymers.
allotropes.
isotopes.
d.
e.
isoforms.
polymorphs.
17. The thermal and electrical insulating qualities of ceramics can be explained by ________
a. significant band gaps.
b. small band gaps.
c. Cooper pairs.
d. the Meissner effect.
e. the low conductivity of positively charged holes.
18. Which statement below regarding vapor pressure is not correct?
a.
Vapor pressure is an intensive property.
b.
The substance with the stronger intermolecular forces has the lower vapor pressure.
c.
Vapor pressure increases with increasing temperature.
d.
Pure water has a higher vapor pressure at a given temperature than seawater.
e.
A nonvolatile solute increases the vapor pressure of the solvent.
19. Which intermolecular interactions are likely to result in the lowest vapor pressure of a
substance?
a.
dispersion interactions
d.
ion–dipole interactions
b.
dipole–dipole interactions
c.
hydrogen bonds
e.
ion–ion interactions
20. Which graph best describes how the vapor pressure of a substance varies with temperature
according to the Clausius–Clapeyron equation? ln(P) is plotted on the y-axis, and 1/T is plotted on
the x-axis. The origin (0, 0) is not necessarily located where the axes cross.
a.
b.
I
II
c.
d.
III
IV
21. In the diagram below, one beaker contains pure water and the other contains an equal volume of
seawater. Seawater has various salts dissolved in it. The beakers are sitting in a totally enclosed
chamber, and the outside temperature and pressure are held constant. Identify the statements
below about this situation that are not correct.
I. Water will be transferred from the pure water beaker to the seawater beaker.
II. Water will be transferred from the seawater beaker to the pure water beaker.
III. The vapor pressure of the pure water is higher than the vapor pressure of the seawater.
IV. Pure water evaporates at a faster rate than seawater.
V. Water in the gas phase condenses into both beakers at the same rate.
a.
b.
c.
II only
II and V
II, IV, and V
d.
e.
II, III, and IV
I, III, and IV
22. Indicate which aqueous solution has the highest vapor pressure.
a.
0.1 M KCl
d.
0.1 M MgCl2
b.
0.2 M Na2CO3 e.
0.2 M MgCl2
c.
0.2 M NaCl
23. The solubility of any gas in a liquid can always be increased by ________
a.
increasing the temperature.
b.
using a solvent that can form hydrogen bonds.
c.
using a solvent that is nonpolar.
d.
decreasing the pressure of the gas above the solvent.
e.
increasing the pressure of the gas above the solvent.
24. Which of the following is a colligative property?
I. osmotic pressure
II. vapor pressure
III. density
IV. freezing point depression
V. boiling point
a.
I, II, IV, and V only
d.
II, III, and V only
b.
I and IV only
e.
I, II, and V only
c.
II and IV only
25. Considering that ideal behavior is not always found in nature, which of the following aqueous
solutions would you expect to have the largest van ’t Hoff factor?
a.
0.100 m C12H22O11 (sucrose)
d.
0.100 m NH4Cl
b.
0.100 m (NH4)2SO4
e.
0.001 m NH4Cl
c.
0.001 m (NH4)2SO4
26. The arrow in the diagram below indicates the direction of solvent flow through a membrane in
osmosis. Which solution, A or B, is more concentrated? Explain your reasoning.
27. Which of the solutions shown here will have the lowest vapor pressure? White circles indicate
solvent molecules; black circles indicate molecules of a nonvolatile solute.
a.
c.
b.
d.
28. The pressure inside a bottle of carbonated beverage decreases when it is cooled in a refrigerator.
What is the main reason for this change?
a.
The solubility of carbon dioxide is higher at the lower temperature.
b.
Some carbon dioxide condenses to form a liquid phase.
c.
The volume of the vapor contracts.
d.
The volume of the liquid contracts.
e.
The volume of the bottle contracts.
29. Isopropyl alcohol has a boiling point of 82.3°C. Solutions of isopropyl alcohol in water have
normal boiling points less than 100°C. Is this observation consistent with the following equation?
Explain.
Tb = iKbm
a.
b.
c.
d.
e.
No, boiling point elevation only pertains to ionic solutes.
No, boiling point elevation only pertains to nonvolatile solutes.
Yes, boiling point depression occurs for all solutions.
Yes, the boiling point depression constant for isopropyl alcohol is large.
No, isopropyl alcohol can hydrogen bond with water.