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Oct. 7-9
Leavenworth, WA
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Raleigh, NC |
Ideas?
Suggestions?
We want to hear from you!
If you have a question about the capabilities of the FS-522, please ask us. You may be surprised at its potential in your situation! Email us (info@microlabinfo.com) or click the MicroLab Support in the Quick Links box (above) for other contact information.
If you have an interesting application of the MicroLab system in your lab, we would love to hear from you! Send us an email - just click on the link above.
If you want to contribute a featured lab application to the E-Newsletter, please contact the editor!
What some of our colleagues using the FS522 say:
"It used to be that students would
spend a three-hour lab gathering data. Now, students can focus on what the data means; this enables them to decide quickly whether or not they need to do the experiment over. The discovery process - how the numbers relate to a concept - takes place in the lab, not when the students are
writing their lab reports."
Dr. Carolyn Mottley
Luther College
"I have been using the MicroLab FS-522 in our
general and physical chemistry laboratories. I am impressed with the versatility and the low cost of this interface, it opens new possibilities for experiments."
Dr. David Saiki
California State University Bakersfield
"MicroLab's software is an enormous aid for non-major students to visualize data collection in real time, and leads them to clearly understand the concept of the lab."
Dr. Angie Sower
Montana State University
"I'm continually amazed at the research quality data we get from MicroLab. We can do things in teaching and in under-graduate research at a small institution that we never dreamed possible."
Dr. Tom Kuntzleman, Spring Arbor University
"You have an
exceptional product.
Money is very tight, and I wouldn't be spending this much of it if I didn't think that the MicroLab units were the best
such devices on the market. I think that they will transform and reinvigorate the way we teach chemistry at Oglethorpe."
Dr. Keith Aufderheide
Oglethorpe University
"MicroLab has given us a great step forward in the
Physical Chemistry lab."
Dr. Clemens Heske
The University
of Nevada
Las Vegas
"We used the built-in
spectrophotometer to study the absorption/
transmission properties of different food dyes. The students really took to the graphs produced for
transmittance and absorbance ... they all said it made the ideas we were talking about really clear to see the two graphs."
Dr. "Skip " Wiley
Middlesex Community College
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Electrochemistry in the Curriculum: Using the Power of the FS-522 to Save Time, Save Chemicals, Learn More!
Welcome to the September 2010 issue of the MicroLab E-newsletter! In this issue we explore the topic that seems to get no respect in our curricula - electrochemistry. It always seems to come at the end of the semester, and, teachers being human (mostly), we get behind and wind up giving it short shrift or skipping it altogether. Perhaps some of this is subconsciously deliberate: since the same thing happened to us in college, we feel a little intimidated by the concept as instructors.
The importance of electrochemistry as a concept cannot be understated. A sound foundation in the fundamentals of e-chem is essential even in entry level chemistry and biology courses to understand redox spontaneity, pH and ion selective electrode function, biochemical cell signaling, cell electron transport such as in the respiratory chain (cascading protein and carrier redox values to transfer electrons from NADH to O2), and electrolysis.
OK, so you want to do a better job of getting key ideas like the electrochemical series as a means of predicting spontaneity in a redox couple, or you want students to experience electrolytic processes. Where do you start?
Well, how about with MicroLab? Take the mystery out of electrochemistry with the FS-522 unit and our e-chem module accessories and associated "One click" software routines. MicroLab makes incorporating electrochemistry into the lab curriculum manageable and affordable for the non-electrochemists among us.
There are two broad categories of electrochemical reactions: spontaneous and forced. Spontaneous reactions can be harnessed to produce a potential (voltage) proportional to the free energy change of the system as it proceeds from reactants to products. Such electrochemical cells are called galvanic cells. Ordinarily, these are studied in the laboratory by measuring the cell voltage (potential) the reactions produce under conditions of zero or very low current. This is also the underlying process in pH and ion selective electrodes. MicroLab's FS-522 unit can measure potential differences (voltages) as low as 10 microvolts reliably and reproducibly.
Electrochemical cells that force a chemical reaction are called electrolytic cells. There are two broad categories of electrolytic cell processes, (1) bulk processes in which the composition of the electrodes and/or solutions change by running a significant current through a stirred solution; and (2) diffusion controlled processes, which use micro-electrodes that produce very small currents (microamperes)in unstirred solutions such that the current is limited by the rate of diffusion to or from the electrode; thus the experiments do not change significantly the composition of of the bulk solution.
Examples of bulk electrolytic processes are water electrolysis, electroplating, and coulometric titrations. Examples of diffusion controlled processes are cyclic voltammetry and chronoamperometry.
MicroLab's FS-522 and accessories can carry out bulk electrochemical processes through its digital to analog (DAC) output as it measures the current and applied potential.
Electrochemistry is just one of the many measurements that MicroLab's FS-522 can make. MicroLab's well conceived, user friendly software, its 16 bit resolution (translate: 1 part in 65,000 precision), its rugged sensors and modules, its well tested collection of experiments, and its team of college chemistry educators backing it all up combine to help you make the most of your lab time, your lab space, and your lab budget as you enhance student learning. |
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Featured Product: The Model 152 Multi EChem Half Cell Module for Studying the Electrochemical Series and the Nernst Equation
What can be easier than measuring the voltage of a pair of half cells? Get a digital multimeter. Prepare solutions of copper(II) nitrate and zinc(II) nitrate and place them in separate beakers. Clip a copper wire onto the red lead and a strip of clean zinc onto the black lead. Use a tissue, piece of cloth, or cotton string wetted with a potassium nitrate solution to make the salt bridge. Voila! Read the voltage. How can you improve on that? With the Model 152 Multi EChem module, that's how.
With the Model 152, you can use up to eight different solutions to produce eight half cells, requiring only about 3 mL of each for the entire experiment, greatly reducing waste.
The Model 152 can measure cell potentials using as little as 3.2 mL per well in up to eight sample wells. The porous barrier has minimal diffusion, resulting in very stable potential readings. The leads connect readily to the MicroLab FS-522's integrated banana jack Voltage IN port. | The center well serves as the salt bridge to all eight wells around the perimeter via a polyethylene barrier with 20-60 micron pores. The salt bridge solution is typically a 0.1M to 1M solution of potassium nitrate. It takes about an hour for the salt bridge solution to permeate the pores. This means that it is best to add the salt bridge solution at the beginning of lab so it can start the process while other activity is going on. Of course, the positive side of this is that migration of ions through the porous barrier is extremely slow during the data gathering. In fact, contamination via diffusion is so low that it is possible to reuse the solutions rather than discarding them, further reducing waste. Solutions are made from the nitrate salts of the respective metals. The metals for the electrodes can be obtained from chemical supply houses such as Sigma-Aldrich. The measured cell potential values via the FS-522 Voltage Input jack are rock solid with the drift in cell potentials typically ~1 mV/hour.
Brief electrochemical series showing the potentials relative to the hydrogen electrode as the reference (left scale) and the Pb|Pb(II) half cell as the reference (right scale), the way students would see them.  |
In a single 8 cell experiment, the students can develop a subset of the electrochemical series using 1M solutions in the Ag|Ag(I), Cu|Cu(II), Pb|Pb(II), Fe|Fe(II), and Zn|Zn(II). They can explore additivity of half cell potential differences by measuring the voltages of all 10 pairwise combinations of the five half cells. They can then go on to explore the Nernst equation using 0.10M, 0.010M, and 0.0010M solutions of AgNO3 in the remaining cells. And they can do it all in less than half an hour.
For the Nernst study, the cell potentials of three dilute Ag|Ag(I) half cells were measured against the Cu|Cu(II) half cell. For best results, the 0.010M and 0.0010M AgNO3 solutions should be made up using 0.1M KNO3 as the solvent to maintain approximately uniform activity coefficients in all three Ag(I) solutions. In our trials the slope of the resulting line had excellent linearity and a slope very near to that of the ideal Nernst slope. The Nernst data as well as the Nernst plot can be obtained easily with the FS-522 by using MicroLab's "One Click" Nernst experiment, which can be found by clicking on the Electrochemistry tab of the software main menu.
In a lab section of 24 students working in pairs, less than 50 mL of each solution are needed - for the entire section! And since the entire process takes less than half hour, there is plenty of time to prepare tables and graphs, to explore and to discuss the results - even to redo the entire experiment in the event of a major error in the process - while the students are with you in the lab.
This is another example of MicroLab helping your students to learn more while saving your budget. |
Featured Product: The MicroLab Model 270 Electrochemistry Module for Electrolysis and Electroplating - Using Electrolysis to Measure Avogadro's Number
Michael Collins, Viterbo University, La Crosse WI 54601
For the past half dozen years, Viterbo University's General Chemistry I course has used MicroLab's Model 270 accessory module that plugs into one of the multipurpose sensor ports on the FS-522 unit and a "One Click" experiment to measure Avogadro's Number. The DAC output on the FS-522 is converted into a precisely controlled voltage through the 0-2.5 V power supply for electrolysis in the Model 270. The MicroLab package represents a huge improvement over the old days. We had done a variation on this experiment for many years, using a battery to supply the voltage, a digital multimeter to measure the voltage drop across a 50 ohm resistor in series with the electrolytic cell to get the current, and a stopwatch. MicroLab has turned what had been a logistical and stenographic scramble into a great experiment that gives excellent results.
The electrolytic cell consists of ~30 mL of a 0.1M CuSO4 solution in a 50 mL beaker, a stir bar, and a pair of weighed ~5 mm x ~30 mm pieces of clean copper foil held in place with a cork. Beaker and contents are clamped on a magnetic stirrer at low speed during the experiment.
The 270 has a schematic screen-printed on its face, so the students can see how to connect the electrodes using the supplied leads. The software's "One Click" experiment leads the student seamlessly through an initial process of nulling the current with an open circuit and prompting the student to connect the leads once this process is complete. The experiment then begins automatically.
The screen allows the student to select the
The MicroLab Model 270 Electrochemistry Power Supply  | applied potential from the DAC on the FS-522 through the 270. It also has START, PAUSE, FILE (save),and CLOSE buttons to control the experiment. While the experiment is running, the student sees in real time the applied potential, the time, and the current. There is a graphing window that allows the student to toggle among plots of time vs. current, vs. charge, or vs. moles of electrons. (Of course, the instructor can ask the students to derive the relationships.)
The electrolysis screen showing the the real-time plot of coulombs passed vs. time. Also visible are boxes showing the present values of voltage applied, current, time, Coulombs, and moles of electrons. The voltage applied has to be considered - you want enough to have good current, but too high an applied voltage will result in water electrolysis as a competing side reaction. We use between 0.8 and 1 volt with good results.  |
The experiment is stopped after about 15-20 minutes (900-1200 seconds). The electrodes are re-weighed to get the mass change of each electrode. The resulting data can be used to obtain Avogadro's Number according to the equation:
in which the 63.5 is the atomic mass of copper, "Δ mass" is the mass loss or gain of each electrode, and (I x t) is the number of coulombs passed in the experiment. One also needs to know that 2 electrons are involved with each copper atom oxidized and each copper ion reduced.
In the last three years in which I was involved in this experiment, my sections each averaged 6.0 x 10^(23) at the oxidation electrode, with a standard deviation of about 0.9 x 10^(23). There can be an error at the Cu electrode that is reduced because sometimes a bit of the copper tends to fall off as it is reduced, and so the recovery is somewhat variable.
One can vary this experiment to measure any one of the variables given the others - the atomic or equivalent weight of copper, the charge on a copper ion, or the charge on the electron.
This is a very nice experiment with a data collection phase that takes about an hour to an hour and a half for duplicate runs. This leaves time to pool results, do the calculations, and discuss it all before the students leave the lab. The MicroLab package has helped transform this experiment from a marginal experience to one in which the students actually begin to comprehend what Avogadro's number means. |
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Diffusion Controlled Applications: Affordable Cyclic Voltammetry and More
MicroLab is developing a series of "One Click" experiments to make more advanced experiments in electrochemistry easier and more affordable. We refer you to a recent article ("Affordable Cyclic Voltammetry", J. Chem. Educ., 2009, 86 (9), p 1080 and supporting information) in which the authors detail the use of the FS-522 with MicroLab's Model 290 Sensor Adapter Module to do simple cyclic voltammetry experiments using the Pine Instruments screen printed micro-electrode system.
We plan to develop experiment modules and easy to connect hardware to facilitate cyclic voltammetry, differential pulse voltammetry, chronocoulometry/chronoamperometry with the Pine electrodes, as well as coulometric titration experiments with carbon or other electrodes. The MicroLab FS-522 will not replace a true potentiostat for high end investigations, but soon it will be able to give you and your students the ability to perform these experiments in regular sized lab sections. Keep in touch for the latest developments! |
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Meet the Editor: Michael Collins
Michael Collins is Emeritus Professor of Chemistry at Viterbo University in La Crosse, WI, USA. He taught undergraduate chemistry for 38 years at virtually every level - from introductory chemistry for liberal arts, nursing, pre-med, biology and chemistry majors to advanced courses for senior chemistry and biochemistry majors. He was the 1988 CASE Wisconsin Professor of the Year and has won awards at Viterbo for his scholarship, teaching, and service. He has been active in his local American Chemical Society section, and chaired the planning committee for the Great Lakes Regional Meeting that was held in La Crosse.
His interest in computer data acquisition began in the early 1980s, and he became convinced of its ability to enhance the lab experiences of his students as well as to prepare them to function in a modern lab setting. He has developed experiments across Viterbo's curriculum that use MicroLab for guided inquiry experiments as well as for more routine data logging and analysis. He has also given presentations on the role of computers in the laboratory to facilitate learning chemistry and in the assessment of lab outcomes. He has been using MicroLab products since they first arrived on the scene, and he continues to develop ideas for new applications of MicroLab in undergraduate teaching and research. |
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Please contact us at MicroLab for more information and to learn how simple it is to put these experiments and others just as exciting into your lab classes with the MicroLab FS522 and accessories.
Thanks for reading! We invite your feedback, ideas, and suggestions. As college educators ourselves, we on your MicroLab team value your feedback.
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Sincerely,
 Your MicroLab team
info@microlabinfo.com |
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