Advanced titration plots using spreadsheet scripting

The use of spreadsheets in chemistry is common, mainly in analytical and physical chemistry, where they are used to calculate systems of linear equations, nonlinear equations using the iterative NewtonRaphson method, linear least squares regressions, etc. All these applications are well described in articles (15) and books (6, 7). Besides calculational facilities, commercial spreadsheets also have advanced numerical tools packages that allow sophisticated calculations in multivariate statistics, as well as linear and nonlinear optimizations, Fourier transforms, and much more. These packages often contain graphical facilities that allow 2D and 3D graphics of functions and discrete point sets. However, finding these tools is not easy, because they are usually not readily apparent from the documentation accompanying the programs. The goal of this article is to emphasize the capabilities of spreadsheets in solving specific problems common in chemistry, such as nonlinear curve fitting. Nonlinear least squares fitting is used, for example, in deconvolutions of overlapping bands in vibrational or electronic spectra and in analysis of chemical kinetics. Frequently, fits of nonlinear equations are done using the GaussNewton or Marquardt methods (810). However in this work we use the quasi-Newton method (11).

mentioning

confidence: 99%

Nonlinear Curve Fitting Using Spreadsheets

Machuca-Herrera¹

1997

“…Therefore, students can participate more in the teaching interaction compared to the traditional lab experiments. Simulations on titration have been widely studied. − Drawing complexometric titrations using generic methods in Excel have been developed; however, there are few complexometric titration simulation platforms that are user-friendly. In this study, a complexometric titration simulation program was developed by LabVIEW.…”

Section: Introductionmentioning

confidence: 99%

Developing and Evaluating an Inquiry-Based Online Course with a Simulation Program of Complexometric Titration

Liu

Ling

2021

This study developed a complexometric titration simulation program based on LabVIEW. With built-in approximation and rigorous algorithms, the program can easily simulate and plot a single or a group of complexometric titration curves. On the basis of this program, we developed and implemented an online course to guide undergraduates to (i) compare the differences between the two titration types EDTA (Y) to Metal (M) and M to Y, (ii) explore the influencing factors of a titration jump, (iii) explore the conditions for an accurate titration, and (iv) find evidence for the existence of complexometric equilibrium. Questionnaires from 25 students were used for evaluation. The results showed that the program had high usability, practicability, effectiveness, and user behavior intention. Besides, 92% of the students were willing to use it more in the future and 11 students completed the test with an average score of 124.6 (full score of 150), and the average score of the modules corresponding to each learning goal was high, indicating that the students had achieved satisfactory learning outcomes.

“…Such a quantitative analysis relates a mathematical description and the use of computer software to the experimental data, and therefore, it may significantly improve the understanding of these topics. Graphical simulations of acid–base pH titrations, using a computer spreadsheet, and applications for educational purposes are available. − A theoretical description of titration curves, using a direct single closed-form expression without assumptions and segmentations (dissection of titration curve into two or more segments), is usually problematic since it involves solving a high-order polynomial. , Less complex approaches for data fitting have been proposed that are based on indirect methods using simplified assumptions or functions without direct physical significance. − However, to our knowledge, there are presently no simple tools for students that would combine graphical simulation, theoretical description, and data fitting for amino acid titrations.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Protonation Equilibria of Amino Acids in Aqueous Solutions Using Microsoft Excel

Šarac

Hadži

2021

A Microsoft Excel workbook has been developed to simplify the quantitative analysis of experimentally measured titration curves for diprotic and triprotic amino acids such as glycine, arginine, histidine, and glutamate. Students perform the titration, enter the data into the worksheet, and manually adjust the resulting pK a values to achieve the closest agreement between the experimental and calculated titration curves. At the same time, the students can observe changes in the speciation diagram that illustrates the transitions of differently protonated molecular species during the titration. Through a combination of graphical visualization and analysis, supported by computer software, students learn the most important aspects of the protonation equilibria of amino acid solutions. The knowledge gained can serve as the basis for understanding the behavior of more complex polyprotic acids in aqueous solution and the pK a values of amino acid residues in proteins.