HW 2 Inorganic Materials
Chemistry
Name:
Points: C7780 Date:
Max. 100 points Fall 2018 A
1. (10 pts) Copper metal crystallizes with a cubic close packed (ccp or fcc) structure having a
lattice parameter a = 3.6147 Å. Calculate the Cu-Cu distance (separation) between nearestneighbor
Cu atoms in the crystal. Hint: nearest-neighbor Cu atoms are any two within the same
close-packed layer (plane).
2. (10 pts) Molybdenum metal crystallizes with a body-centered cubic (bcc) structure having a
lattice parameter a = 3.1469 Å. Calculate the Mo-Mo distance (separation) between nearestneighbor
Mo atoms in the crystal. Hint: the nearest-neighbor atoms are aligned along the body
diagonal of the bcc unit cell.
3. (10 pts) The compound AgCl exhibits the NaCl structure. Frenkel defects in AgCl result from
placement of Ag+
ions in T sites of the Cl–
sublattice. These displaced Ag+
ions are associated
with Ag+
vacancies elsewhere in the crystal. Sketch a diagram of the AgCl structure that clearly
depicts the environment around a Ag+
ion in a T defect site. Describe the number and nature of
cation and anion nearest neighbors about the interstitial Ag+
ion. What characteristic or
characteristics of the compound or crystal structure may stabilize such a defect?
4. (15 pts) Use the Born-Landé equation and the appropriate Shannon-Prewitt radii (provided
below) to calculate lattice energies (L0) for the following structures. Comment on results.
NaCl having the NaCl structure: rNa+
(CN6) = 1.16 Å; rCl–
(CN6) = 1.67 Å
NaCl having the CsCl structure: rNa+
(CN8) = 1.32 Å; rCl–
(CN6) = 1.67 Å (CN8 not avail.)
5. (15 pts) a) Write balanced chemical equation for a solid state reaction:
ZnC2O4 + Fe(OH)3  ZnFe2O4
b) What is the driving force in this reaction?
c) Cubic spinel ZnFe2O4 crystallizes with 8 formula units in the cubic unit cell. The cell parameter
a = 8.42 Ǻ. Calculate the density in g cm3
of the material.
NA = 6.022141 1023
mol1
, Ar(Zn) = 65.41, Ar(Fe) = 55.85, Ar(O) = 15,999.
6. (15 pts) The cell parameter for cubic spinel ZnFe2O4 is a = 8.42 Ǻ, for MnFe2O4 a = 8.50 Ǻ.
a) Suggest a reason for the difference.
b) What would be the cell parameter for the mixed-metal phase (MnxZn1x)Fe2O4 when x = 0.25,
0,50, and 0,75.
6. (25 pts) Ferromagnetic magnetite can be crystallized by a vapor transport reaction under
atmosphere of HCl(g) as a transport agent. Powder of Fe3O4 reacts with HCl at hotter end and
crystallizes at cooler end.
a) Write and balance the VPT reaction:
Fe3O4(s) + HCl (g) ⇄
b) Is the reaction endo- or exothermic?
Provide an explanation by using van’t Hoff equation.
Atmosphere HCl(g)Fe3
O4
(s)
1270 K 1020 K









21
0
1
2
12
11
lnlnln
TTR
H
K
K
KK