Computers in General Chemsitry

Goals, Development and Implementation

BGSU Chemsitry

Supported in part by a grant from the National Science Foundation, DUE/CCLI

(This is a preliminary version and it lacks linkages.)

Our primary goal in this project was to bring laboratory computing into our introductory chemistry laboratories. This involved obtaining computers, data interfaces, laboratory sensors, printers and networking as well as generating appropriate experiments and software to support those experiments. We have achieved those goals, although a number of changes occurred between the original design and the final implementation. Those changes also stalled the project and some aspects of the project were completed too late for the desired assessments.

The goal was to provide individual student workstations. These were to be sufficiently portable to be moved in and out of a traditional laboratory as needed without dominating the individual student work area. The proposal targeted at the use of handheld computers (HPC) often categorized as personal data assistant (PDA) devices. At the time of the proposal several models of HPC were the only computers that met our combined restrictions on size (small footprint) and cost (typically $500/ unit.) We also limited our consideration to devices with standard serial input ports (to allow the use of external data systems), to devices with a Windows-CE operating system (to allow programming in a conventional language), to devices with a modest screen size and preferably with a small keyboard for input. Two manufacturers offered products that were attractive.

Casio sold an HPC (Cassiopeia A22T-Computer Extender) for about $400-500 and was offered with a compatible data unit (EA100, $175.) Casio generously provided two systems and sample software for our evaluation.

• This has a "clam shell" case that opens to provide a 6" x 3" LCD screen with stylus input and a keyboard of comparable size.
• It has a (nearly) standard RS232 serial port, an IR port and a proprietary serial port.
  • The RS232 serial port could provide access for data collection and the IR port could be configured to provide a form of networking.
• A HPC unit operating under Microsoft Windows-CE would be familiar to students and applications could be programmed in Visual Basic. A limited version of Power Point and Excel would also be available.
• This unit had clear limitations-- the screen is monotone (640 x 240 pixels) and the computer is limited to about 8-10 Meg of memory.

Hewlett Packard also made several versions that met our requirements, such as Jornada 720 Handheld PC at $750. The HP units were considerably more expensive but had color LCD displays and higher performance figures.

It became clear that such units would really meet our overall goals. During the early development stage, Windows-CE underwent a number of significant changes, leading us to fear that these computers (and applications written for them) would quickly become obsolete. We also feared that we would need an unrealistic commitment to stay abreast of changes. Casio warned that it was not committed to maintain that line of HPC units. HP discontinued the models we were considering and the newer units were more expensive or seemed less compatible with our goals. If the next generation units were incompatible with our units, we would be forced to replace our full collection with new machines in a few years or we would be forced to accommodate a mixture of different machines with different application programs.

Initially we considered but rejected laptop computers for two reasons. First, the cost was significantly higher ($1500-2000 per station) and we felt we would be unable to afford enough units to make the changes we envisioned for our laboratories. We also worried about the footprint-- the smaller HPC units preserved much more of the limited laboratory space allotted to each student. While we were contemplating the limitations of the HPC products, we had the opportunity to acquire a set of 30 refurbished laptops (Toshiba Protege 7020CT ) at a price (<$400) that was less than what we anticipated for the HPC units. Although hardly cutting edge technology these were still Pentium(TM) II devices at 366 MHz, with 128 RAM and a hard drive with 6 GB capacity and they accept a simple Ethernet card; these units were well in excess of our design goals. They were reasonably compact, in part due to an odd arrangement that treated floppy disk and CD disk drive as plug-in accessories.

The second key element was the acquisition of laboratory data from sensors; this requires an Analog to Digital interface unit. With the HPC we were effectively limited to devices that operate through the computer's serial port. Even laptops effectively limit one to interfacing through serial (RS232 or USB) or parallel (printer) port. We considered a number of commercial interface units, limiting our selection to units with 12 bit or higher resolution.

• Casio's EA100 (now EA200) is commercial unit that provides 12 bit ADC. It is compatible both the Casio A22T and with a variety of graphics calculators, but is not easily interfaced to standard computers..
• Vernier Software makes several units including a vintage interface box (Serial Box, $100) and a more versatile unit called LabPro ($220 ) that can connect to either serial or USB ports.
• DATAQ makes a number of small interface units such as the 12 bit DI-154RS . A recent J. Chem Educ. atricle (approx 2003) advocated such units.($150, $100 with a 33% academic discount).
  • Dataq and Vernier provide software, although in each case we found that software too limited and confining. Vernier did provide limited support for people interested in doing their own programming. Although DATAQ now provides such support, it was not available when we were making critical decisions.
• We have recently acquired several LabJack units ( $110.) These are flexible 12 bit units with support for programming in LabView (TM) and other languages. They also include on board amplifiers and versatile Binary I/O lines. If this had been available earlier, we would probably have used them in this project.

• a. Three timers that could be used to control data acquisition cycles
• b. A 12 bit Analog to Digital converter with up to 10 input channels (we use 6.)
• c. A fully functional RS232 serial port
• d. Additional Ports for Binary input and output signals (we incorporated 4 each)
• e. A 10 bit digital to analog converter (we implemented it but have not used it)
• f. The programming memory can accept 4000 instructions. (This seems primitive by modern computer standards, but is more than adequate for our applications.)

Our applications program for the PIC accepts simple commands from a host computer (the lab laptop.) This allows setting the data acquisition rate. (This is nominally 10-20Hz but we can easily achieve 100 Hz. A minor upgrade to several boards will probably allow us 1 msec acquisition rates for a few special applications.) We also can select any combination of six input channels, one of which accepts a pH electrode directly. We can control 4 output binary lines and read 4 input binary lines, one of which allows trigger signals. We can also perform signal averaging during data acquisition.

The host program (on laptop) handles all treatment of data from conversion of voltages to physical units, plotting and interpretation of data. A sophisticated data handling/plotting package to interface with the PIC microcomputer was written by a BGSU senior chemistry/computing science major, Habib Ahmad.

Student Experimental Modules

We developed a series of general chemistry laboratory instructional modules that utilize the computers in a data collection mode. These generally also included tutorial software, often in the form of Power Point (TM) presentations to present and illustrate specific aspects of each experiment. Most of these are described in detail on the PI's web site

http://www.bgsu.edu/departments/chem/faculty/endres/nsf/nsf_home.htm

• 1. A Spectroscopy module with multiple parts, based in part on miniature spectrometers.
  • This includes a low cost flame Atomic Emission Spectrometry unit based on a standard propane torch, an aspirator and an array spectrometer. The nature of atomic emission lines is clearly evident in the spectra and analysis in the low ppm range for alkali metals is routine. We can actually have students generate a calibration curve for Na and K and analyze an unknown in 3-5 minutes of instrument time. More advanced students can be encouraged to identify several deficiencies of this simple system and to make a significant improvement through the use of Li as an internal standard.
• 2. An Electrochemistry module with multiple parts including use of the computers for potentiometric logging of an oscillating clock reaction, redox titrations and coulometric titrations.
• 3. A Acid Base titration module, analyzing multiple titration curves and comparing those curves to simulations.
  • This has resulted in the development of a low cost custom titration stand that allows repetitive titrations in a sort time. We use a miniature peristaltic pump to deliver titrant (10 ml / minute) resulting in a 45-60 second titrations. A low profile magnetic stirrer was constructed from surplus floppy disk drives. The pump and stirrer get electrical power from the computer interface, making a compact, self contained system.
• 4. A kinetics module focusing in part on a spectrometric monitoring of the rapid reaction between hypochlorite ion and bromthymol green.
• 5. The use of computer monitored temperature in existing experiments in solution calorimetry and freezing point depression.
• 6. We have introduced a wider range of titrations in the introductory lab course (including redox, compleximetric and analysis based on Ion Exchange.)

However we also found several bonus enhancements of our instructional labs.

• 1. Additional Power Point (TM) presentations were developed to accompany laboratory modules that do not collect or analyze data via computer. For example, several presentations were produced to accompany a module on "Photography and Other Chemical Based Imaging Processes". The presentation include photographs and animated diagrams, step by step procedures, review of concepts and supplemental topics. The ready availability of computers for each instrument lab site made this realistic on a routine basis.
• 2. The PI has begun to field requests from other courses to use the computers in way they had not previously done. For example, we have upgrade Biochemistry experiments in kinetics. The result was the ability to perform additional runs and obtain more reliable and conclusive results.
• 3. The development of the interfaces was a topics that surfaced repeatedly in upper level laboratory courses and it became a project topic in a "Computers in Chemistry" course the PI has taught for many years.
• 4. As mentioned previously, the use of the PIC Microcomputers has given us the resources to create additional useful systems. For example, we are combining a PIC (timing, serial port communications) with a 19 bit ADC (MAX132 made by Maxim Semiconductors.) This provides high resolution data (without attenuation or range switching) for large and small peaks in gas and liquid chromatography. The MAX132 is a synchronous serial chip that is awkward to use; the PIC can handle the required signals in a very simple manner. We believe this is far superior in cost and performance to the 12 bit ADC we have been using on several chromatographs in our teaching labs.