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Subject: Avogadro's Number

In response to an article I read in the Journal of Chemical Education ( "The Size of a Mole" Toloudis, M., J. Chem Educ. 1996, Vol. 73, No. 4, pg. 348), I have written a program in Basic which performs the counting as described in the article. However, the program doesn't attempt to count to 6.02x1023 because of a limitation with the programming language, and the simple fact that it takes too long! This program is set to count from 1 up to 9.007x1015, which is just below the upper limit I encountered. In addition to performing the counting, when the program has finished it displays the starting date and time, as well as the ending date and time, if you should let it run that long. I have included my source code (bas) file in the event you wish to modify it or you have a program like QuickBasic and only need the bas file.

For those people who don't want to have to mess with a basic compiler, or have no experience working with basic programs, this program has been compiled into an executable (exe) file which you can run on any DOS or Windows based computer. You simply need to download the DOS exe file, put it on the computer you intend to use, and run the program.

I have been using the executable file with my classes. We begin the program the day I first introduce the concept of a mole, and we check up on the progress every couple of days. It takes a while for the students to realize the awesome magnitude of a mole. But, they don't easily forget! I have been using an old 80386 PC and am getting it to count at just over 1 million counts per hour.

A former student of mine wrote a similar program which runs in Windows 95 or higher, and can also be downloaded. This version has a more familiar windows interface. However, it counts slower, even on a newer and much faster computer. (You may need two additional files to run this program. If so, the files MSVBVM50.DLL and COMCTL32.OCX need to be downloaded, uncompressed, and copied to the WINDOWS\SYSTEM folder.)

Note: Theoretically, the faster (newer) your computer, the quicker it will be able to count. You will notice a difference with the DOS exe file! Moreover, this idea is best put to use using a computer that can be left undisturbed in the classroom until it has finished...a long while later.

Note also: Mac users can also enjoy this activity! Instructions are available for those who need help.

Michael Geyer
Deer Park High School, Cincinnati, OH