Abstract

The chemistry of Cu^I and Cu^II is rich, and these oxidation states can be converted into each other by using quite mild or more strong oxidizing or reducing agents, depending on the starting materials and reaction conditions. Thus, this work describes an easy way to obtain yellow copper(I) oxide from copper(II) sulfate, using hydroxylamine hydrochloride as a reductant. In addition, the aqueous chemistry of Cu^II is very abundant, and in basic media, it perfectly exemplifies the chemistry of any transition metal having amphoteric hydroxides. For this purpose, copper(II) hydroxide is prepared from copper(II) sulfate by addition of basic medium. The insoluble amphoteric hydroxide reacts again with a solution of sodium hydroxide to form the corresponding water-soluble sodium tetrahydroxocuprate(II). Finally, an experiment is carried out to demonstrate the instability of Cu^I in aqueous acid medium, which disproportionates to form Cu⁰ and the corresponding water-soluble copper(II) salt. This set of experiments has been designed to be performed in a single 3–4 h laboratory session, and it has been tested several times with second-year undergraduate chemistry students at the University of Santiago de Compostela (Spain).

Abstract

Collective motion in living matter is highly intriguing but can also be observed in charged colloidal systems. Collective motion observed in colloidal systems requires extensive material synthesis, external stimuli, and advanced characterization methods that might be highly costly to be employed for teaching. Besides that, colloidal systems can inherently possess dynamic movements. Generally, colloidal sedimentation is pictured as a linear movement, but under certain conditions autonomously activated sedimentation can be attained. In this demonstration, a simple formation of colloidal tornadoes will be explored by gravitational force as the sole stimulus. This demonstration is ideal for the general public for colloid chemistry learning, and these findings can be coupled to colloidal stability lectures.

Abstract

Modifications of the classical blue bottle experiment, air oxidation of glucose catalyzed by methylene blue under alkaline conditions, were investigated. Following the green chemistry formulation proposed by Wellman and Noble, we studied the visual behaviors of air oxidation of vitamin C catalyzed by redox indicators. New formulations for the chemical traffic light and vanishing valentine experiments are presented in this paper. We also report, for the first time, chemical pattern formation in this oxidation reaction of ascorbic acid. These results open many possibilities for laboratory practicals as well as demonstration activities.

Abstract

There is an increasing focus across all educational sectors to ensure that learning objectives are aligned with learning activities and assessments. An attractive approach previously published is that of curriculum alignment projects. This paper discusses the use of the fun and famous “Elephant’s Toothpaste” experiment as a customizable curriculum alignment project that can be tailored to address a large number of learning activities and learning outcomes in chemistry suitable for students ranging from late high school through to first year university.

Abstract

Nucleophilic addition of 4-methoxyphenol to 4-fluorobenzaldehyde leads to crystalline 4-aryloxybenzaldehyde. This preparation can be carried out in a single laboratory period with an overnight (or longer) crystallization.

Abstract

Engaging students who are not chemistry majors is a significant challenge. Plaster of Paris is a substance well-known to undergraduate students from early life arts-and-crafts endeavors. Within, a lab is described that connects the synthesis and use of plaster of Paris with a number of chemical principles including stoichiometry, acid–base titration, hydration, and reaction yield.

Abstract

A variation on the preparation of the exploding hydrogen balloons demonstration is presented. A simple method for filling a balloon with hydrogen gas is described. Such a method can be used in most laboratories, making the demonstration easily accessible to almost every school.