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…

A chemistry laboratory experiment is described to introduce undergraduate college students to membrane separation technology. This experiment combines a simple nanowire membrane fabrication and visually indicated molecule separation. The membrane is produced via coprecipitation synthesis followed by a filtration assembly process, which can be…

The amount of protein in complex matrices such as food products is an important characteristic, at both a nutritional and a pedagogical level. There are several methods available for protein quantification, from simple UV absorption to mass spectrometry. The most common are based on the interaction of the proteins with colored compounds followed…

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…

Photochemical reactions are the reactions that are induced by light. Many of these reactions are found in natural processes, including photosynthesis and the formation and decomposition of ozone in the atmosphere. Classroom demonstrations are effective in enhancing students' learning and retention. Herein, we have developed a simple demonstration…

Practical experiments enhance students' understanding of basic concepts and promote deep learning experiences in chemistry. The smartphone application of Lab4Chemistry was utilized to replace colorimeters with smartphone camera sensors. Low-cost and readily available materials, including anthocyanin (fresh red cabbage) and common kitchen…

The "Golden Penny" demonstration is a popular experiment that involves treating copper coins with chemical reagents to form brass, an alloy of copper and zinc that has a golden color. Reported here is a very simple modification for forming golden color on copper coins that does not require the use of chemical reagents. Instead, golden…

In this paper, a simple method is described for visually demonstrating that the wavelength of light reduces when entering a medium of higher refractive index. When a violet laser (405 nm) is reflected off the surface of a Blu-ray disc (track spacing 320 nm) diffraction cannot occur since the wavelength is greater than the track spacing. However,…

The yellow-blue color pair has been used in creative artwork such as paintings and designs and in color engineering. Herein we present a method for using the yellow-blue combination in a chemistry lesson dealing with [pi]-conjugated molecules for first-year undergraduate students who are not science majors. The lesson begins with an introduction…

Students quantified the protein content in beer, milk, powdered milk, and whey protein using the Bradford assay. The assay was carried out using absorbance measured at 595 nm (standard method) and 96-well-plate images (proposed method). They built analytical curves using bovine serum albumin (BSA) and casein and determined that protein type…

Plant leaves are green because they contain the green photosynthetic pigments, chlorophylls a and b. Popular science literature, and sometimes even textbooks, state that the greenness is caused by reflection of green light by chlorophyll. In the present study, we compared the reflectance spectra of green leaves to yellow or white leaves of the…

What colors do you use in class when teaching electromagnetism? For many physics educators we simply use what we learned or what is used in the textbook. Browsing through a large collection of introductory physics textbooks reveals that the vast majority use red for the electric field, blue for the magnetic field, and some shade of green for the…

Electrochromism encompasses reversible changes of material's optical properties (color, opacity) under the influence of an external electric current or applied voltage. The effect has been known for decades, but its importance continues to grow due to the rapid development of smart systems and the accompanying demand to build devices that consume…

Chladni patterns are one of the most fascinating physics demonstrations. They can be produced very easily using commercially available apparatus based on metallic plates attached to a mechanical driver, similar to a loudspeaker without the membrane, and a signal generator. The figures are observed using sand sprinkled on the surface of the plate.…

The Arduino microcontroller is currently one of the favorite tools of makers, and many teachers have used it in teaching or experiments. In addition, light-emitting diode (LED) smart lighting is the worldwide trend in lighting. There are many teaching demonstrations or applications of color addition using LEDs. Furthermore, the Internet of Things…