Chemical Education Today
Beginning Calculations in Physical Chemistry Barry R. Johnson and Stephen K. Scott. Oxford University Press: New York, 1997. 176 pp. Figs. ISBN: 01 9855 9658. $24.95.
Johnson and Scott’s book is part of a chemistry workbook series. It provides a set of exercises designed to help students in the early stages of physical chemistry apprenticeship to learn or review basic concepts necessary for a physical chemistry course. For this book we have the comments of two reviewers, which complement and augment each other. EJW This workbook is designed to complement rather than supplement existing textbooks. Its format is one of examples followed by closely coordinated exercises that can be worked directly on the pages of the text itself. The first six chapters present material at a level typically covered in (or before) the first year general chemistry course and the final two chapters move into more sophisticated areas at the level considered in upper-level physical chemistry courses. Johnson and Scott do accomplish their goals by providing a series of exercises of increasing difficulty. The level of the exercises is quite basic and often involves merely inserting numbers into the appropriate formula. Little additional insight is offered through either direct commentary or suggestions for further consideration by the student. Many students could benefit from at least some of the programmed exercises found in this book. However, the elementary nature of the first few chapters may discourage them from continuing on to the more sophisticated material. The scope of the material is evidence of the authors’ extensive teaching experience. The section on powers of ten includes material describing how to use the exponents to allow multiplication or division without the use of a calculator. Although calculators are certainly ubiquitous, mastery of this particular skill allows students to estimate their result and confirm that their calculated result is at least of the appropriate order of magnitude. The discussion of the difference between a liter and a cubic meter is another example of the authors’ understanding of common student pitfalls. The presentation order is puzzling at times. For example, relative velocity and natural oscillator frequency are introduced in Chapter 2, Calculating Masses of Atoms and Molecules. Both of these topics would be more appropriate later in the text. Conversion factors are occasionally used in problems before the introduction of dimensional analysis in Chapter 3. The answers to each exercise are provided immediately after the exercise, which may tempt students to skip actually writing out the solution to each exercise. Providing the answers at the end of the text, while less convenient, might prevent this potential problem. Certain students would benefit from this text, but requiring its purchase would be an additional financial burden— especially considering that students would still need to buy
the textbook along with any appropriate ancillary materials (i.e., solutions manual). I would recommend this text to students on an individual basis. Lisa Emily Chirlian Department of Chemistry Bryn Mawr College Bryn Mawr, PA 19010
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.
JChemEd.chem.wisc.edu • Vol. 75 No. 5 May 1998 • Journal of Chemical Education
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Chemical Education Today
Book & Media Reviews 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. Marius D’Amboise Department of Chemistry University of Montreal Montreal, H3C 3j7, Canada
[email protected] 550
Journal of Chemical Education • Vol. 75 No. 5 May 1998 • JChemEd.chem.wisc.edu
