Page 164 - Essentials of physical chemistry

126 Essentials of Physical Chemistry

FIGURE 6.9 Prof. Lemont Kier, senior fellow of the Center for the Study of Biological Complexity at
Virginia Commonwealth University, speaking to the Hanover Master Gardener Association, which he founded
in 1988. Medicinal chemists have great respect for and interest in natural compounds from plants. Professor
Kier has been the author of seven books and 278 scientific papers to date and was an early pioneer in the use of
molecular orbital theory in pharmaceutical chemistry. (See Molecular Orbital Theory in Drug Research,
Academic Press, New York, 1971.)

The final clever approximation is to define the temperature as an energy analog related to the
make=break probability. It takes scientific creativity to postulate these relationships but they are
based on experience and physical reasoning in an analog way. What are the results?
In Figure 6.10, we see a set of sensible results for what we know about water. At low temperature
the water molecules aggregate to form large clusters, presumably to solidify into a solid mass at 08C
and at higher temperatures there are a few water molecules that have no nearest neighbors,
anticipating the gaseous state of steam. The value of this study is whether it gives a good
representation of what we know about water and that is where some amazing correlations can be
drawn from this simple model. First, f 0 and f 1 are essentially linear in temperature so it is not
surprising that they correlate with the temperature with a good fit as:
2
T ( C) ¼ ( 490:28)f 0 þ (622:60)f 1 þ 4:46; R ¼ 0:996

That is just a matter of fitting linear data to the temperature. The background of Professor Kier is
research in chemical pharmacology where it is a valid strategy to look through large amounts of
biological data and search for correlations and the main goal is to find relationships. This strategy is
more phenomenological than deriving an equation from Newton’s laws of mechanics and the first
order of business is to find relationships through correlations. This is similar to major component
analysis in certain analytical chemistry methods. However, the relationships may not be linearly
independent and further experiments may need to be carried out to determine physical constants for
equations describing those correlations. There is such a theoretical framework in the work of Jhon et al.
[15] called the significant structure theory of liquids. Perhaps the most important meaning of the work
shown here is that a number of properties of water have been shown to have strong correlations to the