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Oxford University Press: New York, 1997. 176 pp. Figs. ISBN: 01
9855 9658. $24.95.
Johnson and Scott's 166-page workbook is divided
into eight small sections covering elementary material that
beginners should, but usually don't, master. A very brief recall
of the concepts that will be used is given at the start of
each paragraph; it is usually followed by an example of
calculations. One or more fill-in exercises are then proposed to
the student. A summary of the equations and concepts
with which the student should be familiar is given at the end
of each section.
The first section reviews powers of 10. It is very
elementary and could have been omitted. The second section
goes on with Calculating Masses of Atoms and Molecules.
Relative masses are clearly distinguished from actual masses;
molar masses from molecular masses. Binding energy of atoms
is obtained from the mass difference between total masses
of all atomic particles and the atomic mass. Reduced
masses, momentum, kinetic energy, de Broglie wavelength as well as moments of inertia and rotational constants of diatomic
molecules are calculated.
The third section deals with Units: Dimensional
Analysis. The chapter begins by recalling the SI - basics as well
as derived units. The Guggenheim notation for tables
and graphics is explained. The material of the section is quite
appropriate for a student in experimental sciences. The
fourth section goes on with Calculating Frequencies,
Wavelengths and Energies. The authors discuss the photoelectric
effect. Exercises cover various regions of the electromagnetic
spectrum: X-rays to microwaves. Section five deals with
calculations involving Pressure, Volume, Temperature: Concentration
and Density. The chapter assumes ideal gases.
Graph Craft is the subject of section 6. It would
have been more appropriate to put it after section 3.
"Reading graphs" treats a single type of graph: a phase diagram.
The next paragraph deals with "Plotting Graph". Again, only
one type of graph, an Arrhenius plot, is examined. Not very
much is given to help the student to craft good graphs; the
approach is intuitive. The section ends with a brief presentation of
regression analysis and how to estimate the quality of a
straight line. The approach is very elementary but it has the merit
of getting the student aware of some of the tools used to
interpret experimental data.
Section 7 deals with the Kinetic Theory of Gases.
Number density, speed and collisions between gaseous molecules
in pure gases and in mixtures, collisions with walls and
surfaces, and mean free paths, are calculated. Perfect gases are
always assumed. A synopsis of the notation used in the section
is given at its beginning; it is the only chapter for which this
is done. Why?
Finally, section 8 deals with Chemical
Thermodynamics. The 40-page section contains problems with work and
heat, Gibbs energy, enthalpy and entropy changes during
chemical reactions, heat capacities, equilibrium constants, yields,
pH and solubility.
Everywhere in the text, students are trained to use a
rigorous language: amount of substance rather than number
of moles, Avogadro's constant not Avogadro's number, etc.
However, some deviations from this rigor are noted: the
comment following the graph on page 37 says: "where the points
have been joined by a smooth curve" when, in fact, the points are joined by straight line segments. In Figure 4.1, page 49,
the names of the colors in the visible spectrum are upside
down. On page 154, it is written that
"Ka values are usually
quoted with the unit M (mol/dm-3)." What does "usually"
mean? Equilibrium constants are dimensionless. The authors
have missed the opportunity to present the notion of
"standard states". K values are not obtained from "concentrations"
but from ratios of "concentration" divided by standard state,
and are therefore dimensionless units, since standard states
have the same units as "concentrations" units.
Many of the exercises illustrate "real" problems.
However, their number is too limited. As a rule, there is only one
solved problem (example) followed by, at most, three exercises.
Overall, new students in chemistry will find the
workbook useful to review basic concepts and develop abilities in
learning how to solve problems in introductory physical chemistry.
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