Exercises 537Exercises 73 and 74 refer to the phase diagram for sulfur on page
- (The vertical axis is on a logarithmic scale.) Sulfur has two
solid forms, monoclinic and rhombic.
0 *73.(a) How many triple points are there for sulfur? (b) Indi-
cate the approximate pressure and temperature at each
triple point. (c) Which phases are in equilibrium at each
triple point?
0 *74.Which physical states should be present at equilibrium
under the following conditions? (a) 10^1 atm and 110°C,
(b) 10^5 atm and 80°C, (c) 5 103 atm and 160°C,
(d) 10^1 atm and 80°C, (e) 10^5 atm and 140°C, (f) 1
atm and 140°C.The Solid State
*075.Comment on the following statement: “The only per-
fectly ordered state of matter is the crystalline state.”
*076.Ice floats in water. Why? Would you expect solid mer-
cury to float in liquid mercury at its freezing point?
Explain.
*077.Distinguish among and compare the characteristics of
molecular, covalent, ionic, and metallic solids. Give two
examples of each kind of solid.
*078.Classify each of the following substances, in the solid
state, as molecular, ionic, covalent (network), or metallic
solids:
Electrical
Melting Boiling Conductor
Point Point
(°C) (°C) Solid LiquidMoF 6 17.5 (at 406 torr) 35 no no
BN 3000 (sublimes) — no no
Se 8 217 684 poor poor
Pt 1769 3827 yes yes
RbI 642 1300 no yes*079.Classify each of the following substances, in the solid
state, as molecular, ionic, covalent (network), or metallic
solids:
Electrical
Melting Boiling Conductor
Point Point
(°C) (°C) Solid LiquidCeCl 3 848 1727 no yes
Ti 1675 3260 yes yes
TiCl 4 25 136 no no
NO 3 F 175 45.9 no no
B 2300 2550 no no*080.Based only on their formulas, classify each of the follow-
ing in the solid state as a molecular, ionic, covalent
(network), or metallic solid: (a) SO 2 F, (b) MgF 2 , (c) W,
(d) Pb, (e) PF 5.
*081.Based only on their formulas, classify each of the follow-
ing in the solid state as a molecular, ionic, covalent
(network), or metallic solid: (a) Au, (b) NO 2 , (c) CaF 2 ,
(d) SF 4 , (e) Cdiamond.
*082.Arrange the following solids in order of increasing melt-
ing points and account for the order: NaF, MgF 2 , AlF 3.
*083.Arrange the following solids in order of increasing melt-
ing points and account for the order: MgO, CaO, SrO,
BaO.
*084.Distinguish among and sketch simple cubic, body-
centered cubic (bcc), and face-centered cubic (fcc) lattices.
Use CsCl, sodium, and nickel as examples of solids exist-
ing in simple cubic, bcc, and fcc lattices, respectively.
*085.Describe a unit cell as precisely as you can.Unit Cell Data: Atomic and Ionic Sizes
*086.Determine the number of ions of each type present in
each unit cell shown in Figure 13-29.
*087.Refer to Figure 13-29(a). (a) If the unit cell edge is rep-
resented as a, what is the distance (center to center) from
Csto its nearest neighbor? (b) How many equidistant
nearest neighbors does each Csion have? What are the
identities of these nearest neighbors? (c) What is the dis-
tance (center to center), in terms of a, from a Csion to
the nearest Csion? (d) How many equidistant nearest
neighbors does each Clion have? What are their iden-
tities?
*088.Refer to Figure 13-28. (a) If the unit cell edge is repre-
sented as a, what is the distance (center to center) from
Nato its nearest neighbor? (b) How many equidistant
nearest neighbors does each Naion have? What are the
identities of these nearest neighbors? (c) What is the dis-
tance (center to center), in terms of a, from an Naion
to the nearest Naion? (d) How many equidistant near-
est neighbors does each Clion have? What are their
identities?
*089.Polonium crystallizes in a simple cubic unit cell with an
edge length of 3.36 Å. (a) What is the mass of the unit
cell? (b) What is the volume of the unit cell? (c) What is
the theoretical density of Po?
*090.Calculate the density of Na metal. The length of the
body-centered cubic unit cell is 4.24 Å.
*091.Tungsten has a density of 19.3 g/cm^3 and crystallizes in
a cubic lattice whose unit cell edge length is 3.16 Å.
Which type of cubic unit cell is it?
*092.The atomic radius of iridium is 1.36 Å. The unit cell of
iridium is a face-centered cube. Calculate the density of
iridium.