Chemistry Reference
In-Depth Information
and B, 15.55 g of A could possibly be combined with
which ones of the following masses of B?
(a) 4.381 g
(b) How much oxygen should be combined with the
same mass of nitrogen as in Example 3.2 to form
the compound nitrogen dioxide, assuming that
there is twice the mass of oxygen per gram of
nitrogen in nitrogen dioxide as there is in nitrogen
monoxide?
(c) What is the percent composition of nitrogen dioxide?
3.91
The atomic mass of chlorine is 35.453 amu. Does any
atom of any isotope of chlorine have a mass of 35.453
amu? Explain.
3.92
The atomic mass of fluorine is 18.9984 amu. Explain
why the answer to the prior problem would not be cor-
rect for this problem.
3.93 (a) Plot mass number versus atomic number for
1
H,
16
O,
56
Fe,
96
Mo,
138
Ba,
197
Au, and
238
U.
(b) Are atomic number and mass number directly pro-
portional?
(c) What can you say about the relationship of these two
quantities?
3.94 The masses of the atoms of the only two stable isotopes
of boron are 10.013 amu and 11.009 amu, and its atomic
mass is 10.811 amu. Calculate the percentage of each
isotope. [
Hint:
Let
x
equal the fraction of one of the iso-
topes, and equal the fraction of the other.]
3.95 Calculate the atomic mass of lithium from the following
data:
(b) 2.920 g
(c) 17.52 g
(d) 5.841 g (e) 8.761 g
3.83
The law of multiple proportions applies to two or more
compounds of the same two or more elements. Show that
the following data support the law:
% H
% S
% O
Compound 1
2.44
39.02
58.54
Compound 2 5.88 94.12
Compound 3 2.04 32.65 65.31
3.84 The law of multiple proportions applies to two or more
compounds of the same two or more elements. Show that
the following data support the law:
% C
% H
% O
Compound 1
52.2
13.0
34.8
Compound 2 74.9 25.1
3.85 A 14.9-g sample of element A reacts incompletely with a
7.11-g sample of element B. What is the total mass of the
product plus the portion of A that did not react?
3.86 Explain why Mendeleyev could predict the existence of
germanium but missed the entire group of noble gases.
3.87 A typical atom has a radius of about
(1
x
)
10
10
m. Estimate
the radius of a typical nucleus.
3.88 Naturally occurring sulfur consists of 95.0%
32
S, which
has a mass of 31.97207 amu, 0.76%
33
S, which has a
mass of 32.97146 amu, and 4.22%
34
S, which has a mass
of 33.96786 amu. Calculate the atomic mass of sulfur.
How many significant digits are there in the final value?
3.89 Calculate the atomic mass of selenium from the follow-
ing data:
Natural Relative
Isotope Abundance (%) Mass (amu)
6
Li 7.5 6.0151
7
Li 92.5 7.0160
3.96
Sodium and iodine react to form one compound only. In
a certain reaction, 10.00 g of sodium and 55.17 g of
iodine react completely.
(a) How much sodium iodide is produced?
(b) How much iodine would react if 10.00 g of sodium
and 75.00 g of iodine were allowed to react?
(c) How much sodium iodine would be produced?
(d) What law allowed you to answer each of the prior
parts of this problem?
3.97 Naturally occurring silicon consists of 92.2%
which has a mass of 27.9769 amu, 4.67% which
has a mass of 28.9765 amu, and 3.18% which has
a mass of 29.9738 amu. Calculate the atomic mass of
silicon.
Natural Relative
Isotope Abundance (%) Mass (amu)
0.87 73.9205
9.02 75.9192
7.58 76.9199
23.52 77.9173
49.82 79.9165
9.19 81.9167
3.90
(a) Calculate the mass of oxygen in a 4.75-g sam-
ple of nitrogen monoxide, using the answer to
Example 3.2.
74
Se
76
Se
77
Se
78
Se
28
Si,
80
Se
29
Si,
30
Si,
82
Se
