Subject: FRACDIST (Fractional Distillation v1.3)

There are published lab activites for using the TI-83 Plus with a CBL 2 unit to collect data for a fractional distillation lab activity^*. However, they specify collecting temperature readings at selected time intervals. Since we aren't fortunate enough to own heating mantles, our students must use Bunsen burners. Moreover, this is usually the first time the students have been asked to gently heat a solution in a uniform manner over an extended length of time. Most have trouble with this at some point during the lab activity, and a graph of temperature versus time becomes too difficult for them to correctly interpret. To "smooth out" their data curves we collect and graph vapor temperature readings for every 2 mL of distillate collected, and have had excellent results. This required us to write our own program. The result was Fractional Distillation (FRACDIST). This program has since been revised and version 1.3 is currently available.

The FRACDIST program was created to be used on a TI-83 Plus with a CBL 2 unit. A temperature probe must be plugged into channel 1. The program collects all temperature readings in degrees Celsius, and uses lists L1, L2, and L6 for temporary and long term data storage. FRACDIST allows the user to repeatedly collect a single temperature reading at the user's request, independent of time. It first prompts the user to enter the volume of distillate collected at the specified temperature reading, and then immediately reads the temperature. The main menu then reappears and the program waits until the user chooses to collect another temperature reading or quit. Upon quitting the program, the user can manipulate the data, which is all stored in lists L1 (volume readings) and L2 (temperature readings). Additional features added to version 1.3 are a connection check to make sure everything is plugged in correctly, and a graph feature. An instruction manual suitable for giving to students is also available.

I hope this program proves useful to you. If you have any comments or suggestions about it, please feel free to contact us. Michael Geyer (chemistry teacher) specified the program parameters and functions needed, and Jeff Benjamin (math teacher) wrote the code for the program.

^* Holmquist, Dan D., Randall, Jack, and Volz, Don, Chemistry with Calculators. Beaverton: Vernier Software & Technology, 2000, section 8. (ISBN 1-929075-04-9)

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FRACDIST
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Michael Geyer (m_geyer@thecatalyst.org)
Deer Park High School, Cincinnati, OH

Jeff Benjamin (mathjeff@fuse.net)
Deer Park High School, Cincinnati, OH