While they are called demonstrations, the interactive nature of this series of spreadsheets makes them useful for student use to examine particular phenomena and as the basis for moving understanding beyond the calculation of numerical results.

This links below are set up to open Excel when you click on them. If your browser is not set up to recognize Excel you will either have to download the files and run them from your machine (you may wish to do that, and are welcome to copies of the files - they are copyright but freely available for non-profit use), or make Excel a helper application for your browser.

All of these sheets use the Comic Sans font (from Microsoft). If you are using a Win95 machine that has Comic Sans available, and you see a strange, and illegible, script font, open the font folder in the Control Panel and double click on Comic Sans. When you close the display box that appears, and reopen the spreadsheet, the problem should be solved. We do not understand the problem, but do know how to resolve it.

Flipping pennies. In this spreadsheet the student tosses up to 100 pennies a number of times, and observes the distribution of the number of heads as the number of trials increases (up to 100). The theoretical probability distribution can also be plotted on the same graph, as can the mean and standard deviation of the experimental data.

Distribution diagrams for metal complex formation. The user can choose the number of ligands (0-6) and the values of the formation constants and observe the effects on the distribution of the various complexes as a function of the equilibrium ligand concentration. This is useful in helping students see why the approximation, taken in many texts, that only one form of complex is important is often invalid.

An interactive demonstration of the angular overlap model of bonding in metal complexes. The student can position ligands in any of 12 positions to construct a variety of complexes, and then vary the sigma and pi interaction energies and observe the d orbital splittings on an energy level diagram.

A set of interactive demos including blackbody radiation, the photoelectric effect, the emission spectrum of the hydrogen atom, effective nuclear charge and radial distribution functions, and the thermodynamics of N₂O₄ dissociation.

Titration curves for the titration of monoprotic acids (weak or strong), and polyprotic acids up with up to four acidic protons, with sodium hydroxide. The user can change the acid and base concentrations, the pK_a's, and the initial acid volume. The first derivative can be displayed and there is a movable cross-hair for more detailed exploration of the curves. The distribution diagram appears as a thumbnail next to the titration curve, and in a larger version below the titration curve.

Distribution diagrams for weak acid/base systems. The user can generate distribution diagrams (alpha plots) for systems involving monoprotic through tetraprotic acids.

Anharmonicity and the Morse potential allows the student to change the extent of anharmonicity from zero, the value for the harmonic oscillator, up to the theoretical potential for a Morse potential.  The student can observe the compression of levels, monitor the ratio of several vibrational transition energies, and watch new vibrational levels appear as the anharmonicity increases.  This version does not allow the student to vary the molecular parameters such as reduced mass, force constant and dissociation energy.  That will follow soon.  Please note that this spreadsheet requires Excel97.

Integration of the Normal Distribution allows the student to integrate the normal curve between any set of limits ranging up to 5 standard deviations on either side of the mean, including both one- and two-tailed integration.

I have developed several sheets for use in inorganic chemistry. One calculates effective atomic numbers of atoms and ions using Slater's Rules. Another is useful in reducing irreducible representations.

• Flick Coleman wcoleman@wellesley.edu