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The Chemical Educator
ISSN: 1430-4171 (electronic version)
Abstract Volume 22
(2017) pp 112-114
A Non-Traditional Approach to Volumetric Analysis: Acid-Base Titrimetry with the Method of Least Squares
Ali Bazzi*, Yiwei Deng, Judith Bazzi, and Ali Badaoui
Department of Natural Sciences, University of Michigan-Dearborn, 4901 Evergreen Road, Dearborn, Michigan, USA 48128-1491, abazz@umich.edu
Received March 2, 2017. Accepted June 7, 2017.
Published: 14 June 2017
Abstract. Traditionally, volumetric analysis has been based on the molarity of a standard solution and the stoichiometric relationship between the titrant and the analyte to obtain the mass percent of the analyte in a given sample. Here, we describe a non-traditional approach based on the method of least squares to perform titrimetric calculations, where the method of least squares is used to find the equation of the line for a standard solution. The equation of the line is obtained by plotting the volume of the standard solution against the mass of the primary standard. This equation is subsequently used to calculate the mass and percentage of the analyte in the unknown sample. This method forgoes the need for molarity calculation and knowledge of the stoichiometric relationship between the titrant and the analyte to arrive at the analyte percentage. The approach was applied to the determination of the mass percent of potassium hydrogen phthalate (KHP) in analyzed commercial solid samples. The results obtained by thirty students in a multi-section analytical chemistry course are reported. The students’ data showed excellent linearity with over 90% of the students reporting R2 values equal to or better than 0.9990. Overall, the results compare favorably with the traditional approach and displayed good accuracy and precision.
Key Words: Laboratories and Demonstrations; analytical chemistry, acid-base titrimetry, potassium hydrogen phthalate, second-year undergraduate, method of least squares, linear regression
(*) Corresponding author. (E-mail: abazz@umich.edu)
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Supporting Materials:
The laboratoryprocedure handout is available. (22 KB)
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