Conventional mobile phone colorimetry usually utilizes the RGB color mode to measure concentration of solutions, but the paper entitled "Determining the Amount of Copper(II) Ions in a Solution Using a Smartphone" proposes the use of hue ("H") to measure the concentration. It is pointed out that the "H" value increases…

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…

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…

An experimental design by combining hydrogel and ethylenediaminetetraacetic acid disodium salt (EDTA) for visually displaying chemical complexation reactions is developed. The Na[superscript +] ions on the [alpha]-l-guluronic acid (G) unit of the sodium alginate molecule undergo an ion exchange with a divalent cation, so that the G units are…

Blue (B), yellow (Y), red (R), and green (G) color-changing dye was used in a general chemistry course for first-year undergraduate students with nonscience majors to highlight the redox reactions written as the gain and loss of hydrogen. The first experiment is a vibrant color variation using a synthetic dye of indigo carmine. The second…

Thin-layer chromatography, which involves the movement of dyes along a silica-coated plate, is used to observe the progress of chemical reactions and to separate mixtures. We took advantage of this phenomenon to devise a method for generating patterns in the shape of numbers with dots (dot matrix). We prepared the azo dyes necessary for generating…

So-called "Color Wonder" markers contain colorless dyes that only display color when used to mark on special "Color Wonder" paper. These markers make use of leuco dyes that only develop color in the presence of acid. These markers provide science educators with a novel chemical system that can be implemented in inquiry-based…

Red onion, "Allium cepa," juice can dye a cloth sample green upon the addition of alum, aluminum potassium sulfate, and this sample can turn red when subjected to an acidic solution. When the red-colored sample is washed with a neutral or alkaline aqueous solution, its color turns green again. These experiments illustrate color changes…

Raman scattering is a powerful tool for revealing the vibrations of molecules, but as a nonlinear optical phenomenon, its signals can change via mechanisms like resonance enhancement that have no direct analogue in infrared spectroscopy. In this work, complementary measurements conducted on 4-nitrophenol and its conjugate base allow students to…

A two to three period analytical chemistry experiment has been developed which allows second year students to explore chemical color tests used to detect adulterated pharmaceuticals. Students prepare several paper analytical devices (PADs) to generate positive and negative controls antibiotics, along with cutting agents such as starch and chalk.…

Stimulating interest in science at an early age is important for STEM education. This work details an educational activity utilizing the anthocyanins found in butterfly pea flowers ("Clitoria ternatea"). This activity was developed for use in official classroom settings, online, and/or at-home with parental or educator guidance. Primary…

A quantitative titration of the amount of magnesium hydroxide in milk of magnesia using only items purchased in grocery and retail stores is reported. Either vinegar or a solution of food grade citric acid serves as the titrant, while food dyes advertised as being extracted from natural sources provide the end-point indicator. An inexpensive,…

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…

Assistive technologies remain important in supporting student learning in both in-person laboratories and the online laboratory environment. In this article, we describe an adaptation of a smartphone technology called the Color Blind Pal app to aid students in complementing online laboratory assignments in a general chemistry course. The app was…