Lakes are artists' pigments made from colorants bound to an inert substrate, usually hydrated aluminum oxide. Before the late 19th century, lakes were made from natural pigments extracted from plants and insects, extracted either directly from the dyestuff or indirectly from waste materials generated in the manufacture of dyed textiles. The first…

Nowadays, technologies involving nanoparticles, colloids, sensors, and artificial intelligence are widespread in society, media, and industry. It is thus mandatory to integrate them into the curricula of students enrolled in chemistry and materials science. To this purpose, we designed a simple assay for the detection of glutathione (GSH) using…

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…

How do cultural heritage scientists and art conservators identify pigments and other painting media in a decorated object or painting, preferably without taking samples that could potentially damage the artwork? A major emphasis in the characterization, authentication, and conservation of works of art and cultural heritage objects is the use 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…

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 simple photometric assembly based in an LED as a light source and a photodiode as a detector is proposed in order to follow the absorbance changes as a function of the titrant volume added during the course of acid-base titrations in the presence of a suitable visual indicator. The simplicity and low cost of the electronic device allow the…

Metallo-supramolecular polyelectrolytes (MEPE) based on iron(II)-acetate and 1,4-bis(2,2':6',2?-terpyridin-4'-yl)benzene are assembled by layer-by-layer deposition on transparent electrode surfaces. When a potential is applied, the color of the film can be switched from blue to transparent. Due to the strong absorption and the fast switching…

Surface-enhanced Raman scattering (SERS) studies of art represent an attractive way to introduce undergraduate students to concepts in nanoscience, vibrational spectroscopy, and instrumental analysis. Here, we present an undergraduate analytical or physical chemistry laboratory wherein a combination of normal Raman and SERS spectroscopy is used to…

This laboratory was developed by undergraduate students in collaboration with the course instructor as part of a peer-developed and peer-led lab curriculum in a general chemistry course. The goal was to explore the hypothesis that crystal violet lactone was responsible for the thermochromic properties of a sipping straw using a FT-IR for…

The food industry uses different additives to give foods and beverages the appearance expected by the consumer. Among them, pigments of natural origin are receiving increasing attention due to safety concerns about traditional colorants and the relevance of a healthy diet. This experiment describes the quantitative determination of the…

A handheld digital microscope (HDM) interfaced to a computer with a presentation projector is used to project an out-of-focus yellow patch on the screen, then the patch is brought into focus to show that, paradoxically, there are red and green but no yellow pixels. Chromaticity diagrams are used to discuss this observation and spectroscopic…

In this article, we present an overview of a suite of light and spectroscopy education materials developed as part of Project LITE (Light Inquiry Through Experiments). We also present an analysis of how introductory college astronomy students using these Project LITE materials performed on the Light and Spectroscopy Concept Inventory (LSCI)…