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…

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…

This experiment demonstrates that copper(II) chloride dihydrate (CuCl[subscript 2]·2H[subscript 2]O) in different solvents (acetone, isopropyl alcohol, or water) displays divergent colors and visible-near IR spectra. Both the reactions of these solutions with 2 equiv of sodium hydroxide (NaOH) and the direct solid-state reaction of CuCl[subscript…

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…

A new organic chemistry experiment aimed to separate the chlorophyll precursor in plant seeds by column chromatography is described. The primary pedagogical goal in developing this experiment is to establish a simple and interesting chromatographic separation to demonstrate basic concepts and the standard procedure for this important lab…

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…

In the course of combining the Sustainable Development Goals (SDGs) with the science education curriculum, the relevance of the micro- and macroalgae in education is based on the biotechnological future-oriented significance and the ever-growing trend toward plant-based nutrition. So, the micro- and macroalgae are finding their way onto the food…

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.…