Determination of Dissociation Constants and Concentration by Microsoft Excel Solver

Norio YOSHIMURAa*, Masanori OKAZAKIa and Naoya NAKAGAWAb

aGraduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology
2-24-16 Nakacho Koganei, Tokyo, 184-8588 Japan
bThe University of Electro-Communications
1-5-1Chofugaoka, Chofu, Tokyo, 182-8585 Japan

(Received: September 29, 2000; Accepted for publication: January 9, 2001; Published on Web: February 14, 2001)

The dissociation constants and concentration of an acid were determined from a titration curve by Microsoft Excel Solver. It is standard attachment of Microsoft Excel Package and a tool for solving optimization problems. A sample titration curve was obtained by the titration of citric acid solution with sodium hydroxide solution. Despite the fact that a titration curve equation is represented as a complicated non-linear equation, Solver was easily able to find a solution. As a result, the first, second and third step dissociation constants and concentration of citric acid were 1.44×10-3, 5.15×10-5, 2.29×10-6M and 5.14×10-3M, respectively. These values were sufficiently close to those in the literature and to experimental values. Calculation time for solving the problem was 8.60 second by even a personal computer with Pentium 90MHz. Since CPU is rapidly developed, Solver may become a powerful tool for problems with more variables in the near future.

Keywords: Excel, Solver, Titration Curve, Dissociation Constant, Citric Acid

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