This research paper aims to propose a novel didactic sequence inspired by an historical/epistemological study of the evolution of spectroscopy and in particular of colorimetry. The working principles of the historical color comparators and the visual color matching method, first proposed by Duboscq, stimulated us in the development of a five-step…

Quinacridone red and violet are visually different colors, an observation confirmed by their visible reflectance spectra and CIE L*a*b* coordinates. However, their IR spectra are extremely similar. Though chemically identical, the two quinacridones are polymorphs. In this experiment, designed for and tested by nonscience majors, the pigments are…

We here propose a simple and fast hands-on activity requiring limited equipment, to introduce students of various levels (bachelor's or high school) and backgrounds (from science to arts) to the chemistry of color. The different colors of stained glass are replicated through the deposition, on ordinary glass slides, of silica coatings colored by…

A fast, operationally simple, and reproducible synthetic protocol for anthraquinone dyes (AQDs), suitable for upper-division undergraduate industrial and organic chemistry laboratory courses, has been developed. This experiment is composed of three stages; the first step deals with the synthesis of AQDs, followed by a purification step, and…

Colorful transitions of various acid-base indicators have been used to illustrate the concept of chemical equilibria, especially in spectrophotometric determination of the equilibrium constants or pKa values. To accommodate an online laboratory environment necessitated by the COVID-19 pandemic, this work employs color analyses from digital images…

The identification of coloring substances is a relevant task in the field of conservation and restoration, but it can be challenging as in real samples the target analytes are inserted in a very complex matrix made of binders and additives. Understanding this concept is fundamental for upper-division undergraduate students interested in…

Introducing chemical equilibrium concepts in undergraduate general chemistry promotes improved understanding of chemical reactions. We have developed an engaging laboratory experiment exploring the equilibrium of cobalt complexation in alcohols using UV-vis spectroscopy and successfully implemented in a large general chemistry class of 378…

In the laboratory experiment described here, students synthesize silver nanostructures (AgNS) with different shapes and sizes to elucidate the shape- and size-dependent optical properties of nanostructured materials. Students also develop understanding of some thermodynamic and kinetic aspects of the synthesis process through this experiment. In…

A laboratory experiment has been developed to illustrate the transformation of silver nanoparticles (Ag NPs) in water containing phosphate anions. The experiment, conducted by high school students, involved hands-on learning to synthesize and characterize Ag NPs via ultraviolet-visible (UV-vis) spectroscopy. This was followed by a UV-vis probe of…

A new undergraduate inorganic chemistry laboratory experiment is presented. An introduction of the spectrochemical series and ligand exchange is explored using the coordination complex dirhodium tetraacetate, Rh[subscript 2](OAc)[subscript 4]. Students have measured the absorption spectra of the Rh[subscript 2] complex in the presence of various…

Pigments, dyes, and transition-metal compounds are made in courses across the undergraduate chemistry curriculum, but student characterization of these compounds' most striking features, their colors, seldom goes beyond verbal descriptions. Affordable, hand-held, fiber-optic reflectance spectrophotometers make it possible to advance students'…

In selecting from a repertoire of traditional kinetics experiments, an instructor often has to choose among having students gain experience with the graphical method, the method of initial rates, or a temperature-dependent experiment in which students construct an Arrhenius plot. This paper presents an environmentally friendly bleaching reaction…

Low cost, open-source analytical instrumentation has the potential to increase educational outcomes for students and enable large-scale citizen science projects. Many of these instruments rely on smartphones to collect the data, mainly because they can effectively leverage a dramatic price-to-performance ratio of the optical sensors. However,…

The complex approximation is widely used in the framework of the Ligand Field Theory for explaining the optical properties of crystalline coordination compounds. Here, we show that there are essential features of these systems that cannot be understood with the usual approximation that only considers an isolated complex at the correct equilibrium…

A laboratory experiment is described that extracts the tetrapyrrolic teal-colored biliverdin IXa, as its dimethyl ester, from commercially available emu eggshells. The extraction of ~10 mg samples of biliverdin is simple and requires two 3 h lab periods: A two-step acid digestion and liquid-liquid extraction, followed by short silica gel flash…