Undergraduate Laboratory Experiment Research Articles

Planets on the table: A laboratory experiment on radiation and planetary effective-temperature concepts

A new undergraduate laboratory experiment demonstrates radiation laws and their applications to climatology and environmental science. The experiment emphasizes the planetary energy budget and effective-temperature concepts. A close look at “planets on the table” brings some unanticipated results that challenge students to think critically, to interpret the results of measurements, and to come to valid scientific conclusions.

Flexural vibration test of a cantilever beam with a force sensor: fast determination of Young's modulus

We describe a simple and very inexpensive undergraduate laboratory experiment for fast determination of Young's modulus at moderate temperatures with the aid of a force sensor. A strip-shaped specimen rigidly bolted to the force sensor forms a clamped–free cantilever beam. Placed in a furnace, it is subjected to free-bending vibrations followed by a fast Fourier transform for identifying the resonant frequency, whereby Young's modulus is calculated from the Euler–Bernoulli beam model. Room temperature moduli obtained for a series of diverse industrial materials (stainless steel, copper, aluminium, Perspex, wood and getinax) are in excellent agreement with the available literature data. The temperature dependence of Young's modulus for stainless steel measured over the 300–600 K interval is analysed.

An approach to Poiseuille's law in an undergraduate laboratory experiment

The continuous growth of computer and sensor technology allows many researchers to develop simple modifications and/or refinements to standard educational experiments, making them more attractive and comprehensible to students and thus increasing their educational impact. In the framework of this approach, the present study proposes an alternative experimental setup, which allows the confirmation of Hagen–Poiseuille's law, governing the flow of real fluids through tubes, a law with numerous important applications in both technology and medicine. In the proposed educational procedure, experimental measurements of fluid outflow are performed with the use of a motion sensor and a suitable computer program, allowing the determination of both the hydrostatic pressure and the flow rate. The dependence of the flow rate on parameters such as viscosity of the fluid, length and radius of the tube and the pressure difference between the ends of the tube are also studied, providing a laboratory activity which is useful and attractive for first year students, especially those of technologically oriented departments.

Preparation and Characterization of Solid Co(II) Pyrimidinolates in a Multifaceted Undergraduate Laboratory Experiment

The [Co(4-pyrimidinolate)2(H2O)n] species, which can be easily and selectively prepared by simple addition of aqueous solutions of the 4-pyrimidinolate organic ligand to Co(II) acetate (or nitrate) aqueous solutions (n = 4, 6) or by controlled heating of the hydrated phases (n = 0), proved to be versatile materials to introduce and discuss a number of different topics and analytical techniques. An integrated set of laboratory experiments, including synthesis, analytical characterization by conventional titration and colorimetric methods, thermal, spectroscopic and structural characterization, as well as advanced analytical techniques (XRF, XRD), are presented in a sequential manner. A modular approach is proposed, allowing this set of experiments to be adapted even at a high-school level, depending on the local availability of analytical instrumentation and on the specific interest (and curiosity) of both the students and their instructors.

Nobel Chemistry in the Laboratory: Synthesis of a Ruthenium Catalyst for Ring-Closing Olefin Metathesis

An experiment for the upper-level undergraduate laboratory is described in which students synthesize a ruthenium olefin metathesis catalyst, then use the catalyst to carry out the ring-closing metathesis of diethyl diallylmalonate. The olefin metathesis reaction was the subject of the 2005 Nobel Prize in chemistry. The catalyst chosen for this experiment is the ruthenium alkylidene complex that is most practical to synthesize in an undergraduate laboratory for reasons of time, safety, and cost of materials. The three-step synthesis of (PCy3)2Cl2Ru(=CH–CH=CMe2) from RuCl3·H2O goes through [(COD)RuCl2]x and Ru(H)(H2)(Cl)(PCy3)2 as intermediates. The latter complex is air sensitive, giving students the opportunity to learn Schlenk techniques. The ring-closed product is purified by column chromatography, and the catalyst and the ring-closed product are characterized by NMR spectroscopy.

Gas Clathrate Hydrates Experiment for High School Projects and Undergraduate Laboratories

We present a laboratory procedure, suitable for high school and undergraduate students, for preparing and studying propane clathrate hydrate. Because of their gas storage potential and large natural deposits, gas clathrate hydrates may have economic importance both as an energy source and a transportation medium. Similar to pure ice, the gas hydrate structure consists of a lattice of water molecules held together by hydrogen bonds. However, the gas hydrate lattice is more complex than that of ice: cages are formed in which the molecules are trapped. Despite the fact that the gas hydrate lattice is less stable than the ice lattice, the van der Waals forces between the guest molecules and the host lattice stabilizes the overall structure. Propane clathrate hydrate is an especially interesting example because the solid is a mixture of two chemicals that are immiscible in the liquid state yet it has a higher melting point than that of pure water ice. A simple procedure is outlined for students ...

Temperature dependence of the capacitance of a ferroelectric material

We present an alternate version of the undergraduate laboratory experiment developed by Dixon [Am. J. Phys. 75, 1038–1045 (2007)] that is suitable for second-year students. We study the temperature variation of the capacitance of a ferroelectric ceramic derived from barium titanate, the Ba(Ti0.9Sn0.1)O3 solid solution. The ratio of tin to titanium is chosen to provide a convenient Curie temperature near 50°C. Using careful temperature control and real-time capacitance measurements, we track the time evolution of the capacitance in response to temperature changes at 5Hz for runs that last up to a day. At temperatures well above the Curie temperature, TC, the capacitance relaxation is well-described by a single exponential decay. Near TC, the relaxation is linear in the logarithm of time over more than three decades. For T>TC, the permittivity deviates from the Curie–Weiss law and follows another phenomenological form commonly used to describe relaxor perovskite-ceramic capacitors.

Determination of rest mass energy of the electron—an undergraduate laboratory experiment

We present a simple Compton scattering experiment to determine the rest mass energy of the electron which is unique for graduate and undergraduate laboratories. In the present experiment, we have measured the energies of the backscattered gamma photons with an NaI(Tl) gamma ray spectrometer coupled to a 1 K multichannel analyser. In order to enhance the backscattered gamma photons, a thick aluminium target is placed over the radioactive gamma source. The rest mass energy of the electron is determined by using 203Hg, 137Cs, 54Mn and 60Co radioactive gamma sources. The measured values are found to agree with the standard value.

Cavity ring down spectroscopy experiment for an advanced undergraduate laboratory

A simple experiment is described that permits advanced undergraduates to learn the principles and applications of the cavity ring down spectroscopy technique. The apparatus is used for measurements of low concentrations of NO2 produced in air by an electric discharge. We present the setup, experimental procedure, data analysis and some typical results.

A Bioanalytical Chemistry Experiment for Undergraduate Students: Biosensors Based on Metal Nanoparticles

We describe an undergraduate laboratory experiment designed as an introduction to modern concepts of a biosensor based on gold nanoparticles. The objectives are to (i) expose students to the development stages of a modern biosensor, (ii) apply electrochemical methods to deposit gold nanoparticles onto electrode surfaces, (iii) immobilize an enzyme (tyrosinase) using glutaraldehyde chemistry, and (iv) perform quantitative analysis of phenol using a biosensor with amperometric detection. The biosensor was characterized in terms of analytical performance (detection limit, linear range, response time, and sensitivity). The Michaelis–Menten kinetic constants of the immobilized enzyme were evaluated by the ability of the enzyme to catalyze the transformation of phenol to quinone, which can be detected electrochemically upon application of an electrical potential. The experiment reinforces the electrochemical and biochemical principles learned in a typical lecture format and can be realized in two sessions of a ...

Synthesis and NMR Spectral Analysis of Amine Heterocycles: The Effect of Asymmetry on the 1H and 13C NMR Spectra of N,O-Acetals

We describe an undergraduate organic laboratory experiment in which students prepare two structurally similar heterocyclic amines: one achiral, 3-isopropyloxazolidine, 2, and the other chiral, (±)-3-isopropyl-2-(4-nitrophenyl)oxazolidine, 3. These N,O-acetals differ only by the presence of a single ring substituent that introduces asymmetry; thus, each compound has distinct 1H and 13C NMR spectral patterns. Each student prepares 2-(isopropylamino)ethanol, 1, and then the class is divided into two groups: one group prepares 2, and the other group prepares 3. NMR spectroscopy clearly indicates that the nuclei of the methyl groups (and the hydrogens of each methylene) of 2 and 3 are enantiotopic and diastereotopic, respectively. Students must explain why the NMR spectra of 3 have more peaks in the aliphatic region and increased coupling in the 1H spectrum, leading to a discussion of prochirality and topicity of ligands within a single molecule. This operationally straightforward experiment is a meaningful exercise in chemical synthesis and spectral problem solving, and students sample the benefits of collaborative work by dividing up the synthetic and analytical tasks and then sharing their data.

Raman scattering spectroscopy of liquid nitrogen molecules: An advanced undergraduate physics laboratory experiment

We describe a straightforward and highly visual experiment designed to demonstrate Raman scattering spectroscopy by measuring the vibrational energy spacing of nitrogen molecules in the liquid phase. Interpretation of the spectrum teaches the principles of elastic and inelastic light scattering and the intrinsic properties of molecules. The use of a pulsed Nd:YAG laser with high peak power leads to a plethora of nonlinear optical phenomena. The presence of highly visible stimulated Raman scattering greatly enhances the normal Raman-shifted signal, allowing for a more engaging laboratory experience in comparison to traditional Raman scattering experiments.

An inexpensive spectroscopic beam monitor for hard X-ray synchrotron applications

We describe an inexpensive beam monitor for hard X-raysynchrotron applications which has good spectroscopic abilities andcan operate without cooling. The device is centred on an inexpensive,commercial off-the-shelf, large area (1.2 × 1.2 mm2) Siphotodiode operated in single counting mode. Measurements carried outat the HASYLAB synchrotron research facility have shown that it isfully spectroscopic across the energy range 8 keV to 100 keV with ameasured energy resolution of ∼ 1.2 keV FWHM at roomtemperature. The measured resolutions were found to be the same underpencil-beam and full-area illumination, indicating uniformcrystallinity and stoichiometry of the bulk. The low cost, simplicityand performance of the detector make it suitable for a wider range ofapplications, e.g., in undergraduate laboratory experiments.

Electrochemical Quartz Crystal Microbalance Monitoring of the Cyclic Voltammetric Deposition of Polyaniline. A Laboratory Experiment for Undergraduates

The electrochemical quartz crystal microbalance (EQCM) has been well established as a powerful tool capable of monitoring in situ an electrode-mass change down to the nanogram or sub-monolayer level in an electrochemical process. In this work an EQCM experiment to monitor the cyclic voltammetric deposition of a conducting polyaniline (PANI) thin film on an Au electrode is designed as a research-like laboratory experiment for fourth-year undergraduates. The EQCM provides dynamic and quantitative information of both electrochemistry and PANI-film mass during the electropolymerization of aniline in aqueous HClO4, providing good understanding of the redox processes of PANI and allowing the current efficiency for PANI deposition and the largest dynamic anion-doping ratio of the leucoemeraldine–emeraldine transition for the prepared PANI to be determined by one single cyclic voltammetric measurement. This experiment is a month-long upper-level project with three-hour laboratory time designed for fourth-year stu...

High-Resolution Vibration–Rotation Spectroscopy of CO2: Understanding the Boltzmann Distribution

In this undergraduate physical chemistry laboratory experiment, students acquire a high-resolution infrared absorption spectrum of carbon dioxide and use their data to show that the rotational�vibrational state populations follow a Boltzmann distribution. Data are acquired with a mid-infrared laser source and infrared detector. Appropriate absorption peak assignments are made by comparison of the experimental spectrum with the high-resolution transmission molecular absorption (HITRAN) database. Integrated absorption peak areas are used as a measure of relative rotational�vibrational state populations. The effect of temperature on the population distribution is explored by sampling the absorption spectrum at several different temperatures, giving students the opportunity to observe the properties of a Boltzmann distribution.

An Undergraduate Laboratory Experiment Using a Simple Photoassisted Fuel Cell To Remediate Simulated Wastewater

A carbon electrode coated with a TiO2/PVC composite is used to demonstrate a light-assisted fuel cell. Initially in a dilute solution of formic acid the current in a cyclic voltammetry experiment is shown to be enhanced when the electrode is exposed to a 60 W tungsten bulb. When a similar electrode is linked in a fuel cell configuration along with an air electrode, there is an enhancement of current on exposure to the same light source. Finally the system can be used to mineralize a dilute solution of formic acid, which is used as a model compound for an environmental pollutant.

An Undergraduate Experiment for the Measurement of Perfluorinated Surfactants in Fish Liver by Liquid Chromatography–Tandem Mass Spectrometry

Perfluorinated surfactants, including perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), are an emerging class of environmental contaminants that have recently received considerable attention. An undergraduate laboratory experiment to measure perfluorinated surfactants in fish liver has been developed. Fish samples, collected by students from local markets and grocery stores, are extracted using an ion-pairing method and analyzed using liquid chromatography�tandem mass spectrometry (LC�MS/MS) employing student optimized instrumental parameters. In nearly all fish liver samples analyzed by students, perfluorinated surfactants were detected. This undergraduate experiment provides a hands-on opportunity for students to learn new sample preparation and extraction procedures and the specific techniques of LC�MS/MS. Students gain an appreciation of both the sensitivity of LC�MS/MS for the analysis of trace environmental contaminants and the importance of quality control when working with trace analytes in complex biological matrices.

Principles of Solution Thermodynamics: Demonstration of Nonideal Behavior of Henry's Law. An Undergraduate Laboratory Experiment

Quantitative analysis of formaldehyde, HCHO, using the Nash reaction has seen a wide application in both the fields of environmental chemistry and medicine. Our group uses portable Nash systems both to monitor trace levels of HCHO (ppbV, 1/109) present in urban air, as well as measure HCHO in urine, an indicator of bladder cancer. Although several techniques are available for the measurement of HCHO, the rugged nature and reliability of modern, off-the-shelf wet chemical monitoring systems places them ahead of other techniques for several applications. Insightful and practical experiments in physical chemistry for the advanced undergraduate laboratory course are possible with this system. Here we discuss a technique to sample both the gas and the liquid phases of a solution of HCHO(aq), permitting the quick and direct determination of the partition coefficient for a nonideal, solute–solvent mixture. Two scenarios are presented to demonstrate factors that influence this thermodynamic ratio: (i) concentrati...

A nitrogen balance experiment using simulated urine samples

We describe an undergraduate laboratory experiment that combines the advantages of problem-based learning with the need for biochemistry students to become proficient in practical laboratory skills. It also avoids the need to obtain ethical approval for recruiting volunteers and eliminates any possible biosafety issues with the handling and disposal of large amounts of urine. Simulated human urine samples are prepared that contain urea, uric acid, and creatinine at concentrations that represent the levels expected in 2 liters of urine collected over 24 h from subjects on various protein diets or during different physiological states. The students measure the nitrogen-containing compounds in the "urine samples" using specific colorimetric assays and use the data they generate to derive knowledge about nitrogen balance and the excretory metabolism of amino acids.

In situ measurement of the energy gap of a semiconductor using a microcontroller-based system

This paper describes a microcontroller-based laboratory technique for automatic in situ measurement of the energy gap of germanium. The design is based on the original undergraduate laboratory experiment in which students manually measure the variation of the reverse saturation current of a germanium diode with temperature using a current-to-voltage converter. After collecting the results students later analyse them to determine the energy gap of the semiconductor. The objective of this work was to introduce interfacing and computerized measurement systems in the undergraduate laboratory. The microcontroller-based data acquisition system and its implementation in automatic in situ measurement of the band gap of germanium diode is presented. The system which uses an LM335 temperature sensor for measuring temperature transmits the measured data to the computer via the RS232 serial port while a C++ software program developed to run on the computer monitors the serial port for incoming information sent by the microcontroller. This information is displayed on the computer screen as it comes and automatically saved to a data file. Once all the data are received, the computer performs least-squares fit to the data to compute the energy gap which is displayed on the screen together with its error estimate. For the IN34A germanium diode used the value of the energy gap obtained was 0.50 ± 0.02 eV.