Safe and high-quality water is essential from both the health and environmental perspectives. Water quality is so important that the United Nations has included water in the 17 Sustainable Development Goals of the 2030 Agenda for Sustainable Development. Thus, the adequate control and treatment of water are necessities. These tasks must be…

Smartphones are increasingly used in higher education and at university in mechanics, acoustics, and even thermodynamics as they offer a unique way to do simple science experiments. In this article, we show how smartphones can be used in fluid mechanics to measure surface tension of various liquids, which could help students understand the concept…

Assuming that textbooks give literary expression to cultural and ideological values of a nation or group, we propose the analysis of chemistry textbooks used in Brazilian universities throughout the twentieth century. We analyzed iconographic and textual aspects of 31 textbooks which had significant diffusion in the context of Brazilian…

A prior study showed that students best make predictions about the outcome of opening a valve between two flasks containing a fluid or vacuum when they view both a demonstration video and a particulate animation, but the study showed no influence from the order in which these visualizations were used. The purpose of this current research was to…

A number of current reports are challenging educators of undergraduate biology students to increase the role, interactions and approaches of other disciplines. The goal stated in these reports is to produce a college graduate with the skills and competencies to solve pressing global problems such as producing ample food, fuels, and making health…

Research-like experiences range from relatively "canned" labs that are highly controlled by the instructor (such as those described in Lord and Orkwiszewski 2006) to more individually designed projects (e.g., Switzer and Shriner 2000; Wyatt 2005). This article describes a laboratory approach that allows for many of the benefits of independent or…

Describes a freshman chemistry experiment in which students separate and identify commonly used drugs by thin-layer chromatography. Materials needed, procedures used, and typical results obtained are included. (JN)

Describes a low-cost ($120) device which eliminates plasma lines in Raman spectra. The device consists of two prisms and two mirrors which are held in a symmetrical relationship to one another so that a particular position will allow only one wavelength to pass through on a given axis. (JN)

Explains and illustrates strange events which occur when two pendulums interact through a variety of interconnections. Phenomena addressed include: pendulums coupled by a spring, rod, or string; vertical and rotational oscillations, and synchronous and mirror-image swinging. A resonant-spring pendulum and a Wilberforce pendulum are also discussed.…

Describes a rapid, visual demonstration of protein separation by gel filtration chromatography. The procedure separates two highly colored proteins of different molecular weights on a Sephadex G-75 in 45 minutes. This time includes packing the column as well. Background information, reagents needed, procedures used, and results obtained are…

Describes a physical/organic chemistry experiment on conductance behavior of hydrogen-bonded species of six salts of easily accessible, nitrogen-containing bases and halogenoacetic acids. The bases and acids used are much cheaper and have comparatively less unpleasant odors than the pyrim puridines and trifluoroacetic acid used in previously…

Background information, procedures used, and typical results obtained are provided for an experiment involving the separation of chlorophyll a and chlorophyll b from their diastereomers. Reasons why the experiment can be easily integrated into most laboratory curricula where high-performance liquid chromatography capabilities exist are given. (JN)

Provides a method for correcting the photoemission from a collector when using the photoelectric effect experiment to determine Planck's constant. The problem results from a negative current through the cell and makes the measurement of the cutoff potential difficult. (DH)

Presents a field formula for calculating speed and flight efficiency of soaring birds. By estimating the size of the bank angle and timing the complete circle, the observer can determine the speed and circling radius on a chart provided. Lift coefficients and flight characteristics of several birds are also discussed. (DH)

Background information, materials needed, laboratory procedures, and typical results are provided for five high performance liquid chromatography experiments (three isocratic and two step gradient separations). Suggestions for further experimentation are also provided, including quantitative determinations and separation of charged solutes. (JN)