A microscale laboratory experiment to investigate the formation and utility of microemulsions is described. Microemulsions are technologically important fluids that can reduce the use of toxic organic solvents. In the experiment, students prepare a microemulsion and compare the solubility of sudan III dye in the microemulsion and in dodecane. They…

A refinement of an argument due to Maxwell for the equipartition of translational kinetic energy in a mixture of ideal gases with different masses is proposed. The argument is elementary, yet it may work as an illustration of the role of symmetry and independence postulates in kinetic theory. (Contains 1 figure.)

The present article presents a didactic proposal oriented to teaching notions of semiconductor physics in secondary education. The methods and the results of a pilot study designed to analyse the effectiveness of a teaching sequence on the topic are also described. The subjects were 60 students, aged 14-15 years, of a secondary school in Seville,…

Nanotechnology is viewed by those in favor of its development in two different ways, and the divide is not recent. This article describes the origins of the differing visions of nanotechnology and examines their broader impacts. The typical history of the field tells nothing about these differing visions, which perhaps misleads. At least two…

An undergraduate laboratory was designed for undergraduate students to make long persistent light emitting diode (LED) indicators using phosphors. Blue LEDs, which emit at 465 nm, were characterized and used as an excitation source. Long persistent phosphors, SrAl[subscript 2]O[subscript 4]:Eu[superscript 2+],Dy[superscript 3+] (green) and…

The reaction of a ketone and an aldehyde in aqueous Na[subscript 2]CO[subscript 2] is described. This experiment is performed in the absence of strong bases or organic solvents and offers the opportunity for students to observe the critical role that reaction temperature and base strength have in determining the product of the base-mediated…

The three-step synthesis of Geodken's macrocycle, H[subscript 2]C[subscript 22]H[subscript 22]N[subscript 4], (5,14-dihydro-6,8,15,17-tetramethyldibenzo[b,i]-[1,4,8,11] tetraazacyclotetradecahexane), in an overall yield of 65% is described. By utilizing the synthesis of the macrocycle's dichloride salt, H[subscript 2]C[subscript 22]H[subscript…

Many general physics laboratories involve the use of springs to demonstrate Hooke's law, and much ado is made about how this can be used as a model for describing the elastic characteristics of materials at the molecular or atomic level. In recent years, the proliferation of computers, and appropriate sensors, have made it possible to demonstrate…

A set of highly atom-economic experiments was developed to highlight the differences between acid- and base-catalyzed ester syntheses and to introduce the principles of atom economy. The hydrochloric acid-catalyzed formation of an ester was compared with the 4-dimethylaminopyradine-catalyzed ester synthesis.

Physicists have known for some time that pendulum motion is a useful analogy for other physical processes. Chemists have played with the idea from time to time but the strength of the analogy between pendulum motion and chemical processes has only received prominent published recognition since about 1980, although there are details of the analogy…

Bond stereochemistry in polyatomic hydrides is explained in terms of the principle of bond energies maximization, which yields X-H straight bonds and suggests the formation of appropriate sp hybrids on the central atom. An introduction to the electron charge distribution in molecules is given, and atomic, overlap, gross and formal charges are…

This study investigates how high school students respond to an environment of authentic science inquiry while participating in an intensive summer institute, the Waksman Student Scholars Programme at Rutgers University. We examined how students apprenticed with expert scientists in a study of contemporary questions in molecular genetics. Students…

This paper reports on a student summer project performed in 2006 at the University of Frankfurt. It is addressed to undergraduate students familiar with the basic principles of relativistic quantum mechanics and general relativity. The aim of the project was to study the Dirac equation in curved spacetime. To obtain the general relativistic Dirac…

Nanometer-scale investigations offer the potential of providing first-principles understanding of tribo-systems in terms of fundamental intermolecular forces. Some of the basic issues and motivation for use of scanning probes in the area of nanotribology is presented.

The effects of the detailed balance on chemical kinetics on the chemical monomolecular triangle reactions are illustrated. A simple experiment that illustrates oscillations, limit cycles, bifurcations and noise are illustrated along with the oscillating reactions.