In chemical synthesis, obtaining product(s) with high purity is a crucial issue from both academic and industrial viewpoints. Higher purity of the product(s) means higher quality and a lower chemical production costs. Sometimes, purification and separation processes are very laborious and lead to significant impacts on the final price of the…

High school students and students in the first years of college have difficulties in understanding the topic of stoichiometry and, in particular, the concept of limiting reactant. Proposals aimed at overcoming these learning obstacles tend to focus on analogies, and there are few sequences that approach teaching from an experimental perspective.…

The pharmacologically active lignans sesamin and sesamolin are minor components of sesame oil and ingredients in OTC dietary supplement capsules. We report an introductory undergraduate organic laboratory experiment combining natural product isolation and spectral analysis in which students isolate a mixture of sesamin and sesamolin by either (1)…

The basic knowledge of chemical formula writing is fundamental for chemistry students, yet many still struggle to learn it. To provide a more interactive and engaging approach that facilitates and reinforces student understanding of chemical formulas and stoichiometry of chemical reactions, we have designed a chemical jigsaw puzzle. Only eight…

Theoretical yield and extent of reaction (degree of completion) are important concepts in stoichiometry and in chemical kinetics. We provide expressions describing theoretical yield (Y) and maximum extent of reaction (fractional yield, f[subscript max]) for five examples of commonly encountered reversible chemical reactions: A [equilibrium sign]…

This is an easy and inexpensive laboratory experiment in which undergraduate students at the Bachelor's degree level in Chemistry can measure formation constants of complexes [Ni(en)[subscript n](OH[subscript 2])[subscript 6-2n]][superscript 2]+ (n = 1, 2 or 3; en = ethylenediamine) through an acid-base titration. The background information…

Presenters' pedagogical choices are strongly affected by whether they view knowledge as coherent or fragmented. This mixed-methods survey study seeks to contribute to epistemological discussions and associated pedagogical suggestions in the context of mole ratio related mistakes evident in stoichiometry calculations performed by in-service…

This activity allows students to visualize how to obtain different stoichiometries with various techniques in a single experiment. The involvement of three phases adds to the student's interest. Instructional materials are provided to facilitate the experimental procedures, interpretation of results, and error analysis. The reaction of Li from a…

Teachers' conceptual subject matter knowledge of stoichiometry is a global concern. Such knowledge is contextually dependent, as is the feasibility of attaining particular outcomes during in-service teacher education workshops. In an attempt to understand what is feasible in various contexts, I explore the relationships between South African…

Over the past decade the Accreditation Board for Engineering and Technology, Inc. (ABET) has changed the general chemistry requirements to include a single introductory course for most engineering majors. There is a focus on outcomes that equip students with the ability to pass the Fundamentals of Engineering (FE) Exam and to work in…

High school students find reaction stoichiometry and the concept of the mole hard to comprehend. Teachers are well aware of the importance of teaching the mole concept and also the difficulty associated with it. In an attempt to improve the understanding of the mole concept with reduced difficulty, an atomic model kit that provides a hands-on…

This article presents and discusses the results of an educational innovation that seeks to introduce the world of molecular gastronomy in chemistry lessons as a means to review stoichiometry and offer an alternative way to learn. In the literature to date, there is no evidence of haute cuisine having been employed to contextualize stoichiometry…

Making optimal pedagogical and predictive use of the radius ratio rule to distinguish between solid state structures that feature tetrahedral, octahedral and cubic holes requires several updated insights. A comparative analysis of the Born-Landé equation for lattice energy is developed to show that the rock salt structure is a suitable choice for…

A good understanding of ternary phase diagrams is required to advance and/or to reproduce experimental research in solid-state and materials chemistry. The aim of this paper is to describe the solutions to problems that appear when studying or determining ternary phase diagrams. A brief description of the principal features shown in phase diagrams…

The "Atoms-First" approach has received considerable attention in the chemical education community over the past few years as an alternative to the standard reaction-based two-semester General Chemistry curriculum. The Atoms-First model emphasizes the electronic structure of the atom as a means to explain and rationalize chemical…