Name: __________________________
Date: ____________ Period: ________
AP Chemistry – OHS – Chapter 12 Practice Work
Mr. Daniel
1. Explain why a cubic salt crystal can be cleaved cleanly into smaller cubes, whereas glass
shatters into randomly shaped pieces.
Metallic and Ionic Solids
2. The mineral fluorite, which is composed of calcium ions and fluoride ions, has the unit cell
shown here.
(a) What type of unit cell is described by the Ca2+ ions?
(b) Based on the unit cell, what is the formula of fluorite?
3. The structure of graphite is given in Figure 2.21.
(a) What type of intermolecular bonding forces exist between the layers of six-member
carbon rings?
(b) Account for the lubricating ability of graphite, that is; why does graphite feel
slippery? Why does pencil lead (which is graphite clay) leave black marks on paper?
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Name: __________________________
Date: ____________ Period: ________
4. The specific heat capacity of silver is 0.235 J/g·K. Its melting point is 962°C, and its heat of
fusion is 11.3 kJ/mol. What quantity of heat, in joules, is required to change 5.00 g of silver
from solid at 25°C to liquid at 962°C?
5) Air conditioners used to use the chlorofluorocarbon CCl2F2 as the heat transfer fluid. The
normal boiling point of CCl2F2 is −29.8°C, and the enthalpy of vaporization is 20.11 kJ/mol.
The gas and the liquid have specific heats of 117.2 J/mol·K and 72.3 J/mol·K, respectively. How
much heat is evolved when 20.0 g of CCl2F2 is cooled from + 40°C to −40°C?
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Name: __________________________
Date: ____________ Period: ________
6) Tungsten crystallizes in the unit cell shown here.
(a) What type of unit cell is this? Explain
(b) How many tungsten atoms occur per unit cell? Explain.
7) Calculate the molar enthalpy of formation, ∆Hf°, of solid lithium fluoride from the lattice
energy (Table 12.1) and other thermochemical data. The enthalpy of formation of Li(g), ∆Hf°
[Li(g)] = 159.37 kJ/mol. Other required data can be found in Appendices F and L.
8) Define the terms intrinsic semiconductor and extrinsic semiconductor. Give an example of
each.
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Name: __________________________
Date: ____________ Period: ________
9) We have identified five types of solids (metallic, ionic, molecular, network, amorphous).
What particles make up each of these solids and what are the forces of attraction between
these particles?
10) Most metals are shiny; that is, they reflect light. How does the band theory for metals explain
this characteristic?
11) Classify each of the following materials as falling into one of the categories listed in Table
12.2. What particles make up these solids and what are the forces of attraction between
particles? Give one physical property of each.
a) Si doped with P:
b) graphite:
c) benzoic acid, C6H5CO2H:
d) Na2SO4:
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Name: __________________________
Date: ____________ Period: ________
12) The band gap in gallium arsenide is 140 kJ/mol. What is the maximum wavelength of light
needed to excite an electron to move from the valence band to the conduction band?
13) Identify each of the following as p- or n-type semiconductors. For each, give a brief
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