In at least two papers published in this "Journal," enzyme free energy diagrams were presented showing enzyme--substrate binding to be nonspontaneous. I present here several different approaches showing that enzyme--substrate binding is "always" spontaneous, and the y-axis of the reaction progress diagrams presented previously…

In order to succeed in biochemistry, students must transfer and build upon their understanding of general chemistry and introductory biology concepts. One such critical area of knowledge is bioenergetics. Student misconceptions around energy and free energy must be addressed prior to learning more advanced topics, such as energy flow in metabolic…

Energy and entropy are two of the most important concepts in science. For all natural processes where a system exchanges energy with its environment, the energy of the system tends to decrease and the entropy of the system tends to increase. Free energy is the special concept that specifies how to balance the opposing tendencies to minimize energy…

Common wisdom holds that ATP hydrolysis is spontaneous because of the weakness of its phosphoanhydride bonds, electrostatic repulsion within the polyanionic ATP[superscript 4]-molecule, and resonance stabilization of the inorganic phosphate and ADP products. By examining the pH-dependence of the hydrolysis Gibbs free energy, we show that in fact,…

Fundamentals of Macroscopic Chemical Analysis is a newly developed foundation-level course that integrates concepts from traditional physical and analytical chemistry courses. The course was designed to serve majors in chemistry, biochemistry, and biology as well as pre-health professional students. The main goal of this course is to develop the…

The Hofmeister series is a recurring trend that ranks ions' abilities to influence various aqueous processes in solution. Herein, a set of project-based experiments was developed for students in an upper-level physical chemistry laboratory to investigate the specific ion effects on the thermodynamics of caffeine partitioning between aqueous and…

The use of free energy plots to understand the concept of thermodynamic equilibrium has been shown to be of great pedagogical value in materials science. Although chemical equilibrium is also amenable to this kind of analysis, it is not part of the agenda of materials science textbooks. Something similar is found in chemistry branches, where free…

In this article, we use a simple lattice model to illustrate the concepts of entropy, free energy, and thermodynamic equilibrium from a microscopic perspective. These physical concepts are based on elementary knowledge of discrete probability distribution and weighted average. Calculations about this model involve basic algebra and counting, which…

Minimizing the energy consumption of desalination processes is an important goal for augmenting freshwater production and mitigating water scarcity. Chemical, civil, mechanical, and environmental engineering students can derive and analyze the energy consumption of desalination processes by applying engineering fundamentals such as thermodynamics,…

As simple and ubiquitous redox-active organic molecules, quinones participate in diverse electron transfer processes in chemistry and biological systems for energy transformation and signal transduction. We introduce here a practical exercise to study the redox potentials of benzoquinone and its two derivatives by combining the electrochemistry…

A central theme in introductory and advanced chemical education courses pertains directly to the transfer of electrons between atoms, ions, or molecules. This article presents theoretical treatments of electron transfer with specific attention toward applying these principles to experiment. The goal is to revitalize teaching electron transfer at…

Teaching fundamental physical chemistry concepts such as the potential energy surface, transition state, and reaction path is a challenging task. The traditionally used oversimplified 2D representation of potential and free energy surfaces makes this task even more difficult and often confuses students. We show how this 2D representation can be…

In this article we examine cases of more classical and less classical nature compared to results found by quantum mechanics and attribute a form of Free Energy discontinuity for each case within a boundary layer. The concept of a boundary layer is broadened as to include areas of first or second variations of the Gibbs free energy. It is…

The laboratory unit demonstrates a project based approach to teaching physical chemistry laboratory where upper-division undergraduates carry out a transient-absorption experiment investigating the kinetics of cis-trans isomerization of N,N-dimethyl-4,4'-azodianiline. Students participate in modification of a standard flash-photolysis spectrometer…

Two-dimensional nuclear magnetic resonance (2D NMR) techniques are regularly used for the determination of RNA structures. In an effort to introduce advanced level students who are generally not acquainted with or exposed to these techniques, this work, which has been designed as a practicum, utilizes a combination of 2D NMR techniques to help…