ChemSolutions
Useful software for Schools, Science & ICT teachers

Reaction Rate Datalogger

Installation

Please ensure that your PC has the necessary hardware and software before trying to use RRD v2.0. I refer you to the datalogging page.

The software is one self-contained .xls file. Copy it into a folder of your choice.

Introduction

The Excel workbook contains three worksheets:

  1. Mass Display - a large display of the mass change, obtained from reading the mass balance. Even a 14" screen can be seen across a laboratory more easily than the balance display; connecting to a projector improves things even more. I usually get the pupils to record mass change against time. Time is not displayed on the PC because I prefer my students to record the mass change and time for themselves as if it was their own experiment.
  2. Reaction Graph - Real time plot of the mass change. I usually show this at the end but you can watch it happen in real-time if you like. It tends to be a little flickery but I can't improve this.
  3. Graph Data - The datalogged data in columns. If the software is used a second time, the existing data on this worksheet is moved to the right to accommodate the new experiment. Use of Excel's graph-drawing capabilities allow you to overlay experiments on the same graph if you wish.

User Guide

These are the steps for producing good datalogging results:

  1. Load RRD v2.0 (choose to 'Enable Macros' when asked). Adjust the column width, row height and font size of the display (Mass Display worksheet) to suit the resolution of your monitor. Alter the display colours to suit your own preference.
  2. Click on Start!
  3. Read the dialog that appears, then click on Begin.
  4. Enter an experiment title - this is compulsory. Don't click OK just yet.
  5. Suitable amounts of materials to prepare are: Marble chips (50g, use chips because powder reacts too fast), and 50mL of 2M HCl(aq). Weigh the marble chips (it's OK to use the balance) into a 250mL Erlenmeyer (wide-necked conical) flask.
  6. Zero the balance with nothing on it and don't zero it again (this step is important).
  7. This step needs to be done as rapidly as possible. Pour the acid from the measuring cylinder into the flask (the flask should not be on the balance in case of spillage), put cotton wool into the neck of the conical flask (prevents mass loss due to acid spray), place the flask on the balance and click on OK (don't press Enter). Datalogging will start as soon as you click OK. The computer will record the starting weight of the flask and subtract it from all further readings - only the mass loss is displayed.
  8. Allow the reaction and datalogging to continue until the reaction has ceased. Click the Stop! button (Mass Display worksheet) to complete the datalogging. You can move between worksheets during the datalogging by clicking the worksheet tabs at the bottom of the screen.
  9. After the experiment, you can view the graph and the data. The most efficient way to save the data is to save the worksheet as a CSV (comma delimited) file using File, Save As on the Excel menu and change the file type on the Save As dialog.

Troubleshooting

Error Message: Compile error in hidden module: Datalog. Caused by a lack of the ActiveX component from JS Payne (which reads data arriving at the serial port) - either it has not been installed properly or it is missing!

Occasionally this worksheet will cause the computer to 'hang', requiring a reboot. This seems likely to be a problem with the ActiveX component from JS Payne. To ensure this doesn't happen, use the worksheet for one experiment, save the worksheet, close it then open it again for the next experiment.

The mass balance needs to be able to send continuous readings to the PC's serial port (COM1:), through a lead which the balance manufacturer should have supplied, or be able to supply. It may not be a standard cable such as you could buy 'off the shelf' in a computer shop. If the mass balance does not seem to be talking to the PC, check the status bar at the bottom of the screen, after getting to the end of step 7 above. It should be displaying the data 'as received' from the balance (i.e. without any processing). Email Chemsolutions with a description of this display (and preferably with some documentation about your mass balance) and I will work on solving this communication problem.

Limitations

Mass change experiments work best when the mass being lost is large rather than tiny. Reactions evolving carbon dioxide (e.g. acid + carbonate) will work a lot better than reactions that evolve hydrogen.