CHEMiCALC is a thoughtfully designed software package developed for use by high school and general chemistry students, who will benefit from the personal tutor mode that helps to guide them through unit conversion, empirical formula, molecular weight, reaction stoichiometry, and solution stoichiometry calculations. The program might also be useful, however, in any environment in which practicing chemists or chemical technicians are faced with repetitive calculations of this nature.

The program comes with more than 100 problems, divided into four directories, ranging from simple one-step unit conversions to chemical reaction stoichiometry problems. Additional problems can be added using the same WorkPad interface that the students see when they use this software in the calculator mode. Problems can be added using a fill-in-the-blank mode or by entering the text of the problem.

The real power of the program lies in its ability to display calculations so that a factor-label approach can be used to check for appropriate unit cancellation and the feedback provided to the student, for example, "Incorrect", "You are within ± 15%", or "You are an order of magnitude away from the answer." Instructors can also customize feedback messages for specific problems. Use of the factor-label approach to calculations can be facilitated by having the units displayed as colored tiles so that the same unit has to have the same color.

Miles Davis was fond of noting that jazz musicians should be judged on the notes they don't play. In a similar vein, the most important feature of this program is what it doesn't do. It never performs the calculation or cancels the appropriate units for the student. The student must always enter a number and a unit in the answer box before the answer is evaluated. If the student needs help, hints and stepwise "show me" data entries are available from the personal tutor. But the hints and helps do not complete the calculation for the student, who must eventually return to the calculator mode.

The CHEMiCALC software does a good job of utilizing the Windows environment. Tool-windows are used to enter chemical elements, molecular formulas, numbers, calculated results, and units in problem-solving exercises or problem generation. Tools include a pair of calculators, an expandable periodic table, a number keypad, and a unit scrolling keypad. One calculator is used to calculate numerical answers only. The second calculator, like the "stack" calculator found in HP calculators, uses RPN logic. It also displays units and can interpret chemical formulas in terms of their molecular weights. For example, it can interpret the entry "C6H12O6" as 180.158 g/mol, which is why this program might be useful for practicing chemists and chemical technicians.

In addition to the calculator and personal tutor modes described above, the CHEMiCALC program provides other modes. An elemental properties mode allows one to examine trends in periodic properties, which can be graphed in either two or three dimensions. Different elements, families, or periods can be chosen by simply clicking on a small periodic table and then returning to the element mode window. Three-dimensional periodic tables can be created by combining one of the physical properties of the elements with the classic periodic table and then rotating the table by up to 360° or adjusting the perspective by up to 90°. There is also a bond-pair mode, which displays the calculation of the bond length, electronegativity difference, and degree of covalent/ionic character of two elements chosen by the user.

There are a variety of features that make CHEMiCALC easy to use, such as the divisor bar in the WorkPad, which inverts fractions in a calculation. Other features make the program useful to students, such as the specific and informative feedback generated when it checks answers, or to instructors, who have access to a "Learning Curve Monitor" that can monitor students' efforts. On a 15-inch monitor, it is easy to open so many windows that they overlap enough to be cumbersome, but this problem is easily solved by closing one or more of them.

The CHEMiCALC program is accompanied by a personal tutor manual designed to help the user who is unfamiliar with the program. For this review, however, we followed the well-established tradition of playing with the program without reading the user's manual. Finding data from the mode windows and entering data from the tool windows was easy, but performing calculations on the WorkPad required a brief consultation of the manual and online help. By the time this review appears, the version of CHEMiCALC that will be shipped will have the manuals available in a semi-interactive form of online help.

Discussion of this program among several groups of chemistry teachers who had not seen the software contained dire predictions of the fate of the nation if its youth have access to a program that does stoichiometry calculations for them. But that is not what this program does. This program does nothing more than what so many of us have done so often in the past, checking students' answers to see if they are right (or wrong) and providing hints about what they might have done wrong in setting up a problem. If you would like to provide access to a computer program that does this, freeing your time to work with students on their conceptual understanding of chemistry, or if you would like a computer program that could be used in class to demonstrate how calculations of this nature are done, you might want to look into the CHEMiCALC software.