Professor Estel Sprague, Ph.D., Department of Chemistry, University of Cincinnati
> A General Note About Electronic Data Acquisition
> A Note about Post-Acquisition Data Analysis
> A Note About the Impact of Spectroscopy Capabilities
> Final Instructor Comment
Comparative Analysis by Experiment —
> Line Spectra of Elements
> Reaction Stoichiometry (Complex Ion Formation)
> pK Of An Indicator
> pH Titration Curves
> Behavior of Gases
> Enthalpy of Reaction
> Freezing Point Depression
> Voltaic Cells
The introduction of MeasureNet networks into the freshman chemistry laboratories of the University of Cincinnati has resulted in extensive changes to the lab program. These changes may be divided essentially into two types: (a) new experimentation that was either impossible or impractical with previous equipment, and (b) modernization of older experiments long part of the established curriculum. A variety of examples of each type are described in this document.
A General Note About Electronic Data Acquisition
One concern about electronic data acquisition in the freshman lab is the possibility that interfaces will be little more than black boxes to the students—magically producing numbers students will have difficulty relating to the reality of the performed experiments. Whether this proves true in practice is very much in the hands of the instructor and the data analysis students are required to carry out. It is generally not difficult for the students to understand the measurements themselves (like temperature, pressure, pH, etc,.). It is in the extraction of the chemically-meaningful information from the measurements, i.e., the goal of the experiment, that the black box may have a tendency to appear.
Measurenet provides a convenient, efficient way for students to collect large quantities of high-quality raw data. MeasureNet saves the data in a simple format readily importable into a variety of other applications. The instructor, therefore, has the ability, and the responsibility, to determine how black-boxy (i.e., how automatic) to make the analysis. At one extreme, the students would never take away from the lab anything but raw data, along with instructions perhaps for how to perform the desired analysis. At the other end, software would produce the desired results with little involvement of the students. At the University of Cincinnati, we fall somewhere between these extremes in most of our experiments.
Electronic data acquisition and analysis in our freshman laboratories typically follows two general paths. In one case, we obtain the desired analysis results from simple graphs of raw data while still in the lab (e.g., freezing point from a cooling curve). The availability of the instructor or teaching assistant in the lab to answer questions during this process is an obvious advantage. MeasureNet purposely makes creating graphs of raw data easy and automatic. One of our goals is to introduce our students to how things are likely to be done in typical modern labs in research and industry, so the drudgery of manually producing such graphs is intentionally eliminated.
In the second case, when significant manipulation of raw data is required in a particular experiment, we choose from various options. For example, certain pre-defined, automatic manipulations are available with MeasureNet through custom print codes, in which graphs are automatically produced in the lab of the manipulated data. Other options include analysis after the lab using spreadsheets with pre-defined manipulations (macros). The extent to which these provide automatic analysis can vary a great deal, depending on the macros. Students take their data with them in some electronic form, or using MeasureNet's ability to store data remotely for later retrieval, they download their data later, along with spreadsheets to be used in analysis (see A Note About The Impact of Post Acquisition Analysis).
Perhaps the most noticeable result of the much greater ease of collecting and manipulating experimental data is the dramatic increase in the amount of experimentation that can be done in a lab period. Instead of performing an experiment once with manual data collection, with a lot of the focus required to be on the data acquisition process itself, the students can perform multiple experiments of a given type, gaining exposure to a wider variety of chemical systems and behavior. Rather than electronic data acquisition being too black-boxy, we find that it provides powerful tools to do the drudge work, enabling us to to introduce the students to more (and more meaningful) chemical experimentation.
A Note About The Impact of Post-Acquisition Analysis
MeasureNet's design enables the students to easily upload data files to individual, password-protected accounts on a remote server. In several experiments, the students do this and then retrieve their data after class at home, in their dorm rooms, etc., along with Microsoft Excel files containing macros written to assist with post-acquisition data analysis. This provides a useful alternative for efficiently dealing with large amounts of data generated in some experiments, especially when students are sharing data with others on their network. They are able to aggregate data with greater efficiency and benefit from expanded data when performing analysis for a number of experiments. It was virtually impossible for us to do this when operating without electronic data acquisition and would still be cumbersome without Measurenet's network-based approach.
A Note About The Impact of Spectroscopy Capabilities
Each MeasureNet system in our department includes a high-quality (1 nm-resolution) spectrometer available for efficient sharing by all students on the network. This has enabled the introduction of a variety of experiment s that make use of spectroscopy, going well beyond what was feasible and practical earlier with our numerous Spectronic 20s. In addition to utilizing the networked spectrometer for concentration determination in some experiments by means of Beer's Law, other examples such as Line Spectra of Elements, Reaction Stoichiometry, and pK of an Indicator are described in the following experiment-specific tables/sections.
Final Instructor's Comment
Although it is not a pedagogical item, the design of MeasureNet proves to be of considerable importance to the person in charge of the lab. With everything but the probes permanently built-in, always ready to simply switch on, and especially with only one PC per network to deal with, the additional burden involved with all of this electronic data acquisition is much less that we might have expected, that indirectly leads to improved pedagogy by freeing us from the need to waste large amounts of time on pedagogically unproductive maintenance, set-up, and oversight activities.
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