Laboratory activities are a prevalent and essential part of chemistry learning because of their potential to help students develop problem solving abilities, visualize chemistry concepts learned in lecture, and gain practical skills. However, learning in the laboratory environment is not without its challenges. For example, cookbook-style…

The Beer-Lambert law is a fundamental relationship in chemistry that helps connect macroscopic experimental observations (i.e., the amount of light exiting a solution sample) to a symbolic model composed of system-level parameters (e.g., concentration values). Despite the wide use of the Beer-Lambert law in the undergraduate chemistry curriculum…

A green chemistry experiment is presented for teaching an undergraduate quantitative analysis/analytical chemistry laboratory class through the use of black tea leaf extract for the determination of iron in supplement tablets. Dried tea leaf is a safe, low cost, and widely available source of natural extract that can be used in place of more toxic…

The oxidation of iron is an important reaction due to its high economic impact. In this laboratory exploration, the total order of this reaction was determined using commercially available handwarmer packets that rely on the iron-oxygen reaction to generate heat. The active ingredient in the handwarmer packet is iron, which interacts with…

The elementary reaction sequence A ? I ? Products is the simplest mechanism for which the steady-state and quasi-equilibrium kinetic approximations can be applied. The exact integrated solutions for this chemical system allow inferring the conditions that must fulfill the rate constants for the different approximations to hold. A graphical…

Many students enroll in college general chemistry with an interest in a medical career. In those (and alternative) careers, they will need to make critical decisions about data and how that data are acquired. A significant portion of introductory lab experiments are, in principle, but not necessarily in practice, devoted to understanding how…

Throughout the general chemistry lab curriculum, a common shortcoming is the way in which students measure, record, and manipulate quantitative data. From initial measurements with different digital and analog instruments to proper conversions, calculations, and comparisons, students are often expected to be experts before they have been taught…

The method of least squares (LS) yields exact solutions for the adjustable parameters when the number of data values n equals the number of parameters "p". This holds also when the fit model consists of "m" different equations and "m = p", which means that LS algorithms can be used to obtain solutions to systems of…

A visual regression analysis using the least absolutes method (LAB) was developed, utilizing an interactive approach of visually minimizing the sum of the absolute deviations (SAB) using a bar graph in Excel; the results agree very well with those obtained from nonvisual LAB using a numerical Solver in Excel. These LAB results were compared with…

When dissolving copper in nitric acid, copper(II) ions produce a blue-colored solution. It is possible to determine the concentration of copper(II) ions, focusing on the hue of the color, using a smartphone camera. A free app can be used to measure the hue of the solution, and with the help of standard copper(II) solutions, one can graph a…

The article describes the use of Mathematica, a computer algebra system (CAS), in a high school chemistry course. Mathematica was used to generate a graph, where a slider controls the value of parameter(s) in the equation; thus, students can visualize the effect of the parameter(s) on the behavior of the system. Also, Mathematica can show the…

Describes a method for determining the rate constants of enzyme reactions involving two substrates with the use of double reciprocal plots. (MLH)

Describes a freshman chemistry experiment designed to introduce scientific methodology, provide practice in measurement skills, and illustrate a fundamental chemical relationship (conservation of volume). Provides the experimental design, a materials and equipment list, sample calculations, and results. (JM)

Provides a first experiment for college chemistry that provides insights into scientific procedures without presupposing any detailed knowledge of chemistry on the part of the student. Requires the student to measure successive masses and volumes and use these values to determine the density from the slope of the graph. (MVL)