A Computerized Soda Ash Experiment for First-Year College Chemistry The traditional soda ash experiment involved a simple titration to the methyl orange end point and logarithm calculation to &Lain percent sodium carbonate in soda ash. At Concordia College (Moorhead, Minnesota) this experiment has been remodeled to include a double indioator titration, pH titration, plotting of first and second derivative plots, and calculation of data by an IBM computer. The hydrochloric acid solution is standardized with primary standard sodium carbonate as it illustrates many neutralization principles not readily observed with THAM(tris-hydroxymethylamino-methane). The first and second end points are observed by using phenolphthalein and methyl purple, respectively. Thestudent finds this procedurevery interesting as it effectively illustrates the neutralization theory discussed in lecture. In our laboratory the student titrates primary standard and two samples of soda ash by this double indicator technique. A third soda ash sample is titrated potentiometrieally using a pH meter and only relevant results are submitted to the computer center. An Affit Fortran Program for an IBM 1620 computer is used to obtain all values for a. first and second derivative plot; saving the student many hours of repetitious calculations. The computer program handles a maximum of 160, ml versus pH, value sets. Data printed out at the computer center snd received by student appears on print out sheets with the following column headings: ML. TITRNT
pH
DEL PH
DELTA V
DpH/DV
D(DpH/DV)
SEC D
These data are now used to graphicdly determine the end point. The student mav now. if desired. submit final exoerimental data to cornouter center m d a second Affit Proeram will calculate to revitalize a sods. ash experiment. BATTELLE-NORTAWEST
P.O. Box 999 G ,AREA 325 B ~ I L ~ I N300 99352 RICHLAND, WASHINGTON
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Journal of Chemical Education
