Undergraduate Chemistry Laboratory Research Articles

Argument-Driven Inquiry: An Introduction to a New Instructional Model for Use in Undergraduate Chemistry Labs

This article presents a new instructional model called Argument-Driven Inquiry (ADI) that can be used in undergraduate college chemistry laboratory courses. ADI is designed to provide students with an opportunity to develop their own method to generate data, to carry out investigations, use data to answer research questions, write, and be more reflective as they work. In addition, the ADI instructional model integrates opportunities for students to engage in scientific argumentation and peer review. This article describes the ADI instructional model, provides the empirical and theoretical foundation for it, and presents a detailed semester pacing schedule for general chemistry I laboratories, peer-review guides, and instructor scoring rubrics.

Laboratory Experiment on Electrokinetic Remediation of Soil

Electrokinetic remediation is a method of decontaminating soil containing heavy metals and polar organic contaminants by passing a direct current through the soil. An undergraduate chemistry laboratory is described to demonstrate electrokinetic remediation of soil contaminated with copper. A 30 cm electrokinetic cell with an applied voltage of 30 V is used to demonstrate the redistribution of copper in sand initially contaminated with 0.24 M copper chloride solution. The copper content in sand is measured by acid extraction followed by complexometric titration. The measurement of the pH across the cell is used to demonstrate the difference in mobility between the H+ and OH– ions during the electrokinetic process.

Measurement of the Compressibility Factor of Gases: A Physical Chemistry Laboratory Experiment

In this article, we describe an experiment for the undergraduate physical chemistry laboratory in which students measure the compressibility factor of two gases, helium and carbon dioxide, as a function of pressure at constant temperature. The experimental apparatus is relatively inexpensive to construct and is described and diagrammed in detail. Students analyze their data to determine values for the second virial coefficient for each gas, which may then be compared with the literature. The experiment demonstrates the nonideality of real gases.

A Portable, Low-Cost, LED Fluorimeter for Middle School, High School, and Undergraduate Chemistry Labs

A low-cost portable fluorimeter was constructed using a 360 nm LED for excitation and a silicon photodiode for detection. The instrument is simple to operate and has been used to investigate fluorescent whitening agents extracted from various brands of paper, to determine the linear range and limit of detection of quinine in various commercial tonic water samples, and to quantify the amount of vitamin B1 in commercial multivitamin supplements. The instrument is straightforward to construct and to use and facilitates the introduction and hands-on application of spectroscopy, fluorescence, and related topics in middle school, high school, and undergraduate laboratory courses.

Development of an electronic nose sensing platform for undergraduate education in nanotechnology

The teaching of the different aspects of a sensor system, with a focus on the involved nanotechnology, is a challenging, yet important task. We present the development of an electronic nose system that utilizes a nanoscale amperometric sensing mechanism for gas mixtures. The fabrication of the system makes use of a basic microfabrication facility, as well as an undergraduate chemistry laboratory for material synthesis and preparation. The sensing device consists of an array of cross-reactive sensors composed of metal-oxide semiconducting nanoparticles. Each sensor in the array produces a unique response in the presence of a target gas, allowing the sensor to determine the identity and concentration of multiple gases in a mixture. The educational aspects include microheater simulation and fabrication, design and fabrication of interdigitated electrodes, development of interfacing circuitry and software, development and calibration of a sensory array, sol–gel processing of nanoparticle films and their characterization, and details of the fundamental chemical sensing mechanism.

Molecular Iodine Fluorescence Using a Green Helium−Neon Laser

Excitation of molecular iodine vapor with a green (543.4 nm) helium−neon laser produces a fluorescence spectrum that is well suited for the upper-level undergraduate physical chemistry laboratory. Application of standard evaluation techniques to the spectrum yields ground electronic-state molecular parameters in good agreement with literature values. The use of a green helium−neon laser provides advantages in data collection, data analysis, cost, and safety relative to other I2 excitation sources.

A Global Perspective on the History, Use, and Identification of Synthetic Food Dyes

This article presents a brief history of the artificial coloration of foods, a discussion of the worldwide use of synthetic food dyes, and methods for separating and identifying 14 dyes in common use globally. The United States Food and Drug Administration presently has certified seven synthetic dyes for use in foods. An additional seven synthetic dyes are commonly found in foods in other parts of the world. The structures of these 14 dyes, as well as their separation by paper chromatography and identification by visible absorption spectroscopy are discussed. Also included are specific ideas on how to incorporate experiments involving synthetic food dyes into the undergraduate chemistry laboratory curriculum.

Optical Sensors for Manual and Automatic Titration in Undergraduate Laboratory

ABSTRACT The classic undergraduate titration analysis is upgraded using instrumental detection of end point with color indicators. Several color sensors (CCD-based spectrophotometer, video camera with RGB digitalization, photodiode with appropriate filters) were tested in order to replace the visual indication of the end point with different indicators. The developed procedures show adequate characteristics such as a short titration time and accuracy of 0.1–1%. Specific features of particular titrations such as hardness of water and argentometric titration of chloride are discussed. In the author's opinion, this experimental setup represents an affordable ($100-level) option for an undergraduate or advanced high school chemistry laboratory.

Gunshot Residue Analysis in the Undergraduate Laboratory Using Toy Cap Guns

ABSTRACT The authors developed an experiment for the undergraduate analytical or forensic chemistry laboratory in which gunshot residues (GSRs) produced from toy cap guns are analyzed by laser-induced breakdown spectroscopy (LIBS). Alternatively, the experiment is readily adaptable to any emission spectroscopy technique. This project allows students to investigate the development of a forensic method while addressing proper sampling techniques used in forensic investigations. Students were able to develop a library of blank samples, establish signal detection limits to address legal considerations for determination of false-positive and -negative error rates, and optimize an emission spectrometer.

Faculty Perspectives of Undergraduate Chemistry Laboratory: Goals and Obstacles to Success

Faculty perspectives of the undergraduate chemistry laboratory were the focus of a study to articulate the goals, strategies, and assessments used in undergraduate teaching laboratories. Data were collected via semistructured interviews with faculty (N = 22) from community colleges, liberal arts colleges, comprehensive universities, and research institutions engaged in teaching or supervising undergraduate laboratories. The goals for general chemistry, organic chemistry, and upper-division laboratories are described and compared among faculty who have received NSF-CCLI (now called NSF-TUES) grants to implement changes in laboratory and those who have not. Problems and limitations to success in laboratory are also reported, and the impact of these obstacles on student achievement and laboratory curricula is discussed.

Thermochemistry to the Rescue: A Novel Calorimetry Experiment for General Chemistry

A novel calorimetry experiment that (i) provides “real-world” connections, (ii) assists students in learning thermochemistry, and (iii) uses equipment commonly found in an undergraduate general chemistry laboratory was implemented at our institution. Ultimately, students design a custom heat pack to treat the frostbitten hand of an Alaskan pipeline maintenance worker. First, students measure and use the specific heat of Vienna sausage to approximate the hand’s specific heat. Students obtained a mean specific heat of 3.1 ± 0.5 J g−1 °C−1 for Vienna sausage, which compares favorably with generally accepted values for the human body’s specific heat. Second, students qualitatively determine heats of salt dissolution and identify a salt for their heat pack. Next, students quantitatively determine their chosen salt’s heat of dissolution. Finally, using the Vienna sausage’s specific heat, students estimate the heat required to raise the temperature of the hand from 15 °C (frostbite risk) to 37 °C, calculate the ...

Excited-State Processes in Slow Motion: An Experiment in the Undergraduate Laboratory

Lasers have transformed chemistry and the everyday world. Therefore, it is not surprising that undergraduate chemistry students are frequently exposed to fairly advanced laser techniques. The usual topics studied with lasers are molecular spectroscopy and chemical kinetics. Static and dynamic fluorescence experiments seem to be particularly popular. The phenomenon of phosphorescence, on the other had, has received much less attention in the undergraduate physical chemistry laboratory. A few years ago, we developed a laser experiment that introduced students to the phosphorescence quenching of the carbazole−naphthalene system under steady-state and pulse-excitation conditions. The purpose of that experiment was to demonstrate the experimental and theoretical aspects of triplet−triplet nonradiative energy transfer between two aromatic molecules. Subsequently, we modernized the experiment by introducing an inexpensive and easy-to-use Ocean Optics data acquisition system. This not only greatly simplified the experiment, but also made it more accessible to students. This article presents the upgraded version of the experiment together with suggestions for practical implementation.

Correction to Personal Multifunctional Chemical Analysis Systems for Undergraduate Chemistry Laboratory Curricula

Correction to Personal Multifunctional Chemical Analysis Systems for Undergraduate Chemistry Laboratory Curricula

Chemical Vapor Deposition of Aluminum Oxide Thin Films

Chemical vapor deposition (CVD) is a process routinely used to produce thin films of materials via decomposition of volatile precursor molecules. Unfortunately, the equipment required for a conventional CVD experiment is not practical or affordable for many undergraduate chemistry laboratories, especially at smaller institutions. In an effort to expose undergraduate chemistry students to this valuable materials science technique, a convenient, inexpensive apparatus was constructed to deposit thin films of aluminum oxide on a silicon wafer substrate. The system features the controlled hydrolysis of the water-sensitive precursor liquid, dimethylaluminumisopropoxide, at 200 °C. The experiment described herein is customizable depending on the resources available and lends itself to an inquiry-based format. A discussion of overall student sentiment and pedagogical outcomes from this module is also included.

Microwave Instruments: Green Machines for Green Chemistry?

In this column, the authors discuss the ease of using microwave ovens for various activities in the undergraduate chemistry laboratory and suggest a few models of microwave systems for readers to consider.

Thermodynamic Exploration of Eosin−Lysozyme Binding

We developed a modular pair of experiments for use in the undergraduate physical chemistry and biochemistry laboratories. Both experiments examine the thermodynamics of the binding of a small molecule, eosin Y, to the protein lysozyme. The assay for binding is the quenching of lysozyme fluorescence by eosin through resonant energy transfer. In both experiments, students measure fluorescence quenching at constant lysozyme concentration as a function of added eosin and determine the dissociation constant, KD, and ΔG° for binding. In the physical chemistry experiment, students repeat the fluorescence measurements at several temperatures to determine the temperature dependence of ΔG°, and therefore ΔH° and ΔS° as well. Typical student results yield a KD of (28.3 ± 7.5) μmol L−1 and a binding ΔG° of (−26.04 ± 0.70) kJ mol−1 at 25 °C. ΔH° and ΔS° of binding are found to be (−4.1 ± 2.5) kJ mol−1 and (73.9 ± 8.7) J mol−1 K−1, respectively. This pair of laboratories represents an interdisciplinary module in which students in different courses examine the same system but from different perspectives and with different emphases.

A New Java Program for Graphical Illustration of the Franck−Condon Principle: Application to the I2 Spectroscopy Experiment in the Undergraduate Physical Chemistry Laboratory

Requires FCIntensity.jar Themeasurement and subsequent analysis of I2 absorption and emission spectra is a standard experiment in the undergraduate physical chemistry laboratory (1-5). The observation of interesting intensity alternations in the dispersed fluorescence spectrum and the lack of clear alternations in the absorption spectrum are a manifestation of the Franck-Condon principle, which is an important concept in physical chemistry. Discussion of the Franck-Condon principle, although often neglected in the undergraduate curriculum, can illustrate the connection between vibrational eigenfunctions and transition probabilities. We have developed a portable, flexible, and user-friendly program to illustrate the relationship between Franck-Condon factors and the observed spectral intensities. Students also explore the effects of changing spectroscopic parameters on the predicted spectra. FCIntensity is a Java program that computes the eigenfunctions and eigenvalues of the Morse oscillator Hamiltonian using numerical methods. The program is easily uploaded and implemented on a personal computer and permits facile manipulation of input parameters (Figure 1). As part of the analysis of our I2 laboratory, the students are given the ground state Re (2.6664 A) value and asked to obtain the best-fit B-state Re by comparing the calculated intensity distribution to experiment. Although the calculated intensity patterns do not exactly match experiment (given the Morse approximation that can be discussed), only B-state Re values near 3 A provide an acceptable fit. The remarkable sensitivity is surprising to most students. The comparison between calculation and experiment also reveals the dependence of the spectrum to other parameters. For example, changes in Te, ve, and De for the B-state result in shifts of the spectral positions of all emission lines, while changes in De and ve for the ground state result in changes in the spacing between emission lines. Once the emission spectrum has been analyzed, we ask the students to use the program to simulate the measured absorption spectrum using the same parameters. Calculations using v00 =0, 1, 2 provide visual confirmation of the location of the hotbands and, through inspection of the vibrational wave functions, the origins of the nonoscillatory behavior relative to the emission spectrum.

O uso de aparelhos de micro-ondas domésticos em aulas experimentais de química orgânica: nitração de salicilaldeído

The use of microwave in chemistry has known benefits over conventional heating methods, e.g. reduced reaction times, chemical yield improvement and the possibility if reducing or eliminating the use of organic solvents. We describe herein a procedure for the nitration of salicylaldehyde in water using a domestic microwave oven, which can be used as an experiment in the undergraduate chemistry laboratory. The experiment involves safe and rapid preparation and identification of the position isomers by thin layer chromatography and 1H NMR, or by their melting points.

Quantification of Sugar Mixtures with Near-Infrared Raman Spectroscopy and Multivariate Data Analysis. A Quantitative Analysis Laboratory Experiment

An experiment for Raman spectroscopy in combination with multivariate data analysis was designed and implemented in the undergraduate analytical chemistry laboratory curriculum. Raman spectroscopy is currently considered among the most important nondestructive routine optical analysis tools. An experiment is presented demonstrating the capability of Raman spectroscopy in combination with principal components analysis and regression (PCA/PCR), which was applied to determine the composition of complex sugar mixtures that cannot be adequately quantified using conventional univariate analysis methods.

Analysis of Dextromethorphan in Cough Drops and Syrups: A Medicinal Chemistry Laboratory

Fluorescence spectroscopy is used to determine the quantity of dextromethorphan hydrobromide (DM) in over-the-counter (OTC) cough drops and syrups. This experiment is appropriate for an undergraduate medicinal chemistry laboratory course when studying OTC medicines and active ingredients. Students prepare the cough drops and syrups for analysis, compare their results with analysis of a DM standard solution and explore interference from other ingredients (food coloring, corn syrup, and methyl cellulose). Students also perform a standard addition analysis to obtain a quantitative result for the quantity of DM in a cough medicine. This experiment can be a straightforward laboratory exercise to be completed in one laboratory period or an open-ended investigation spanning two or more laboratory periods. This exercise gives students experience in chemical analysis of an OTC medicine and could be extended to other medications or food products.