One of the hardest skills to teach undergraduates in a laboratory exercise is how to identify the impacts of the limitations of the methods and underlying assumptions on the results obtained. We are developing a laboratory activity in which experimental conditions play a significant role in the outcomes obtained. This exercise is based on the spectrophotometric determination of an equilibrium constant for the iron(II) nitrate and potassium thiocyanate reaction. In this laboratory, students will study two equilibrium conditions created by varying the concentrations of the reactants. In the first system the quantities of the reactants will differ greatly, ensuring that the equilibrium distribution results in the majority of the limiting reactant being consumed. The second system will use reactant quantities that will result in significant quantities of the reactants remaining in the equilibrium system. It is expected that the second system will produce less variability. Using this system, students will characterize the equilibrium in the two systems and compare the reproducibility and how it relates to the properties of the system. Questions will be created to help guide students to the learning objectives. In this presentation we will report on the effectiveness of our experimental design.

Investigations of the impact of experimental error on the spectrophotometric determination of an equilibrium constant

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.