Page 42 - Essentials of physical chemistry

4 Essentials of Physical Chemistry

TABLE 1.1
Boyle’s Data on the Dependence of the Volume
of a Gas on the Pressure of the Gas
Volume Pressure P V
2
48 29 = 16 1398
9
46 30 = 16 1406
15
44 31 = 16 1405
8
42 33 = 16 1407
5
40 35 = 16 1413
38 37 1406
4
36 39 = 16 1413
10
34 41 = 16 1415
3
32 44 = 16 1414
1
30 47 = 16 1412
5
28 50 = 16 1409
5
26 54 = 16 1412
13
24 58 = 16 1412
1
22 64 = 16 1409
11
20 70 = 16 1414
14
18 77 = 16 1402
14
16 87 = 16 1406
7
14 100 = 16 1406
9
12 117 = 16 1411
for the uncertainty of the data to the nearest 1=16 in., so Boyle assumed that the product is constant.
This leads to the simplest form of ‘‘Boyle’slaw’’:
PV ¼ C 1 ¼ P 1 V 1 ¼ C 1 ¼ P 2 V 2 ) P 1 V 1 ¼ P 2 V 2
so we have

P 1 V 2
:
¼
P 2 V 1
Here C 1 is the first constant in this study. We should note that Boyle’s experiments were carried out
at essentially constant room temperature but do we know that temperature has an effect? Not from
this data.
Historically, there was a competition between England and France, which had the effect in
science of development of English units still used in the United States and the metric system
developed in France and preferred in modern science. Thus, it is interesting that early work by
Charles on the temperature dependence was extended by Gay Lussac several years later and is now
known as the Charles–Gay Lussac law.

CHARLES’ (JACQUES-ALEXANDRE-CÉSAR CHARLES) LAW

While hot air balloons are familiar today, the first documented demonstration occurred on June 5,
1783, when Joseph Montgolfier used a fire to inflate a spherical ‘‘hot air’’ balloon about 30 ft in
diameter that traveled about a mile and one-half before it returned to earth. The news of this caused