Chemistry Reference
In-Depth Information
(1.00 mol) (0.0821 L
#
atm/mol
#
K) (273 K)
1.00 atm
PP14.5
Heat
mc
¢
t
nRT
P
PP12.27
V
128 J
(4.00 g) (
c
) (15.3°C)
22.4 L
128 J
(4.00 g) (15.3°C)
2.09 J/g
#
°C
c
PP12.30
NH
4
Cl(s) £ NH
3
(g)
HCl(g)
4.29 L of is also expected. Because the mole ratio is 1:1
and the separate gases are at the same temperature and pres-
sure, the volume ratio is also 1:1. Nothing can be said about
the volume of the solid.
NH
3
(123 g) (0.442 J/g
#
°C) (16.4°C)
PP14.7
Heat
892 J
Heating the iron takes much less energy because its heat
capacity is so much lower.
PP14.10
0
m
metal
c
metal
¢
t
metal
m
water
c
water
¢
t
water
13 Atomic and Molecular Properties
PP13.1
(186 g) (
c
metal
) (26.4°C
74.0°C)
(251 g) (4.184 J/g
#
°C) (26.4°C
18.0°C)
Cl
is much bigger because it has added an electron, but
the nucleus has not changed. The greater interelectronic re-
pulsion causes an increase in size (from
10
3
J
c
metal
(186 g) (
47.6°C)
8.8
2
1.0 J/g
#
°C
0.99
10
10
m
c
metal
to
1.81
10
10
m).
The metal is magnesium.
Na
6
Ne
6
O
2
PP13.2
PP14.11
0
m
metal
c
metal
¢
t
metal
m
water
c
water
¢
t
water
Na
(11.3 g) (0.44 J/g
#
°C) (
t
f
60.0°C)
All three species have 10 electrons. has the most positive
nucleus (11 protons) and, therefore, the smallest size; has
the least positive nucleus (8 protons) and, therefore, the
largest size.
PP13.3 (a)
Te
(b)
Mg
PP13.4 (a)
N
(b)
Mg
(c)
F
PP13.5
The third ionization, which breaks the octet of electrons in the
third shell.
PP13.7 (a)
Polar covalent
(b)
Ionic
PP13.8 (a)
Trigonal pyramidal
(b)
Angular
(c)
Linear (Any two-atom molecule
must
be linear.)
PP13.9
Trigonal pyramidal
PP13.10
The hydrogen-oxygen-oxygen angle is about 108
, nearly the
tetrahedral angle. The hydrogen atoms can rotate about the
oxygen-oxygen bond to form different conformations, for
example:
0
O
2
(97.2 g) (4.184 J/g
#
°C) (
t
f
19.0°C)
4.9
7t
f
29
8
°C
406.
7t
f
772
7
°C
0
411.
7t
f
802
5
°C
t
f
19.5°C
3.71
10
4
J
37.1 kJ
PP14.12
16.4 g(2260 J/g)
The heat required to vaporize water is much greater than that
required to melt the same mass of ice.
PP14.13
For cooling the liquid water to
0°C:
(40.0 g) (4.184 J/g
#
°C) (0.0°C
14.4°C)
Heat
241
0
J
To freeze the water:
Heat
40.0 g(
335 J/g)
13,4
0
0 J
For cooling the ice:
(40.0 g) (2.089 J/g
#
°C) (
16.3°C
0.0°C)
Heat
136
2
J
Total heat
241
0
J
(
13,4
0
0 J)
(
136
2
J)
H
T
H
H
TS
H
T
17,200 J
O±O
O±O
O±OH
T
In each process, the minus sign indicates that heat is being re-
moved.
(5650 g) (4.184 J/g
#
°C) (16.5° C)
PP14.15
Heat
390,
0
00 J
PP13.11
Bond Type Molecular Polarity
(a)
Nonpolar No dipole
(b)
Polar Dipole
(c)
BrF Polar Dipole
(d)
Polar No dipole
(e)
Polar No dipole
The molecules of and are symmetric, so the effects
of the polar bonds cancel out. In the polar bonds do not
balance one another. In diatomic molecules, such as and
BrF, a polar bond always results in a polar molecule, and a
nonpolar bond yields a nonpolar molecule.
PP13.12
Hydrogen, which has the least mass and the fewest electrons
PP13.14 (a)
through
(c)
All three form hydrogen bonds.
390.
0
kJ
Cl
2
Because 390.
0
kJ was added to the water, the heat of the reac-
tion is
NF
3
390 kJ.
BCl
3
PP14.16
C
7
H
16
(
/
)
11 O
2
(g) £ 7 CO
2
(g)
8 H
2
O(
/
)
BeH
2
¢
H
7
¢
H
f
(CO
2
)
8
¢
H
f
(H
2
O)
¢
H
f
(C
7
H
16
)
BCl
3
BeH
2
7(
393.5 kJ)
8(
285.9 kJ)
(
187 kJ)
NF
3
,
4855 kJ
Cl
2
PP14.17
For the products:
110 kJ
1 mol CO
286 kJ
1 mol H
2
O
¢
H
f
4 mol CO
a
b
5 mol H
2
O
a
b
187
0
kJ
For the reactants:
126 kJ
1 mol C
4
H
10
¢
H
f
1 mol C
4
H
10
a
b
126 kJ
14 Solids and Liquids, Energies of
Physical and Chemical Changes
PP14.1
¢
H
¢
H
f
(products)
¢
H
f
(reactants)
(a)
Molecular
(b)
Ionic
(c)
Macromolecular
(
187
0
kJ)
(
126 kJ)
10
5
)
3
10
16
I
2
PP14.3
molecules
This number of molecules contains
(2.5
1.6
1740 kJ
10
16
3.2
I atoms.
For 1.00 mol, the answer is the same within limits of signifi-
cant digits.
PP14.4
Because molecular solids have relatively weak intermolecular
forces, the molecular solid must be the one with the melting
point of 90°C.
