A simple diffraction experiment was designed using banana stem as natural grating. Coherent beams of lasers with wavelengths of 632.8 nm and 532 nm that pass through banana stem produce periodic diffraction patterns on a screen. The diffraction experiments were able to measure the distances between the slit of the banana stem, i.e. d = (28.76 ±…

This article describes a combined UV-photometer and fluorimeter constructed from 3 LEDs and a few wires, all held in place with Lego bricks. The instrument has a flexible design. In its simplest version, two UV-LEDs (355 nm) are used as light source and to detect absorption, and a third LED, in the visible spectrum (e.g., 525 nm), is used to…

Exothermic reactions can present safety hazards and there is a recognized need for reaction safety education at the undergraduate level. We present an experiment that illustrates the pitfall of direct scale-up of an exothermic reaction that can lead to thermal runaway. The iodide-catalyzed hydrogen peroxide decomposition reaction yields…

In this paper we present a reasoning line for introducing the Pauli exclusion principle in the context of an introductory course on quantum theory based on the sum over paths approach. We start from the argument originally introduced by Feynman in "QED: The Strange Theory of Light and Matter" and improve it by discussing with students…

Solubility is frequently introduced at the high school and introductory college levels through the symbolic domain using net ionic equations and solubility product constants. Students may become proficient with spectator ion cancellation and skilled with algorithmic mathematical applications of solubility without obtaining a deeper understanding…

A simple capacitive cell for dielectric constant measurement in liquids is presented. As an illustrative application, the cell is used for measuring the degradation of overheated edible oil through the evaluation of their dielectric constant.

A laboratory experiment is described in which a simple characterization of a historical lime mortar is made by the determination of its approximate composition by a gravimetric method. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) are also used for the qualitative characterization of the lime mortar components. These…

A research project for senior undergraduates of chemistry has been developed to introduce syntheses of a series of monodispersed semiconductor PbS quantum dots (QDs) and their characterization methodologies. In this paper, we report the preparation of monodispersed semiconductor PbS QDs with sizes smaller than the exciton Bohr radius using a…

First-order kinetic decay rates can be obtained by measuring the time-dependent reflection spectra of ultraviolet-sensitive objects as they returned from their excited, colored state back to the ground, colorless state. In this paper, a procedure is described which provides an innovative and unique twist on standard, undergraduate, kinetics…

Introducing students to a multidisciplinary research laboratory presents challenges in terms of learning specific technical skills and concepts but also with respect to integrating different technical elements to form a coherent picture of the research. Here we present a multidisciplinary series of experiments we have developed in the Electronic,…

We present an adaptation to an experiment previously published in this "Journal". The experiment was designed to determine the heat capacity ratios of gases by measuring the speed of sound using a modified Kundt's tube. The experiment yielded excellent results for all of the gases and gas mixtures measured. Although elegant in its simplicity, it…

A practical exercise for developing a simple cost-effective solar ultraviolet radiation dosimeter is presented for use by middle school science students. Specifically, this exercise investigates a series of experiments utilising the historical blue print reaction, combining ammonium iron citrate and potassium hexacyanoferrate to develop an…

A modification of the mixed-aldol synthesis of dibenzylideneacetone, prepared from acetone and benzaldehyde, is described wherein acetone is replaced with a series of cyclic ketones with ring sizes of 5-7 carbons. The structural variations in the resulting conjugated ketones produce regular variations in the UV-vis absorption spectra. The choice…

Simple measurements of the decay time of cathodoluminescence are described. Cathodoluminescence is used in many devices, including computer monitors, oscilloscopes, radar displays and television tubes. The experimental setup is simple and easy to build. Two oscilloscopes, a function generator, and a fast photodiode are needed for the experiments.…

Equipment for demonstrating Newton's third law and the energy conservation law in mechanics have successfully been constructed utilizing fine spherical plastic beads in place of metal ball bearings. To demonstrate Newton's third law, special magnetized Petri dishes were employed as objects, while to examine the energy conservation law, a…