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Modeling Scenario


Author(s): Brian Winkel

SIMIODE - Systemic Initiative for Modeling Investigations and Opportunities with Differential Equations

Keywords: linear regression kinetics chemistry order of reaction chemical reaction chemical data infusion differencing

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Resource Image A student is assigned the task of collecting data on a chemical reaction and does a poor job of collecting data. She only collects data at the start and end of a number of ten minute intervals and does not keep track of when the observations are made.


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Article Context

Resource Type
Differential Equation Type
Qualitative Analysis
Application Area
Pedagogical Approaches
Vision and Change Core Competencies - Ability
Bloom's Cognitive Level


A tired chemistry graduate student, Karla, who really wants to play Magnate II on her computer with her buddies, is stuck on Friday night lab duty. Just before he leaves the lab late at 9:00 PM her advisor says, ``I am going to set up an experiment involving first order reaction in Formula X which will run for about 6 hours and I wonder if you can collect the data because the AutoData device is on the fritz. This is important to me and I will return in the morning for the data which I need to write up for the Monday Departmental Seminar. You can start it whenever you want, but I need the data by 10:00 AM tomorrow morning.  Just hit the START button on the apparatus. Immediately, the initial amount of Formula X in ng will be injected into the solution while the stirrer moves it uniformly through the solution.  At the same instant a steady but constant amount of  Formula X compound will be added to the beaker with my patented ChemInfuser. At all times the reaction takes place, consuming the Formula X compound. I want you to formulate a kinetics model and confirm my theories about the rate of reaction. Blah, blah, blah ldots Thanks.''

 Whoosh, he is out the door! He is dating another graduate student and she continues to wonder if she should say something to the chair of the department about that.

Here is the amazing part. Karla never once recorded the actual time of her observations in her log book, just the amount of Formula X, noting which was the first of her two, separated by 10 minutes, observations, over and over, throughout the night. It was simply amazing (and regrettable) that she did not record the actual time of ANY observations, except the first two at time t = 0 min and t = 10 min. That's it!!

Article Files


Author(s): Brian Winkel

SIMIODE - Systemic Initiative for Modeling Investigations and Opportunities with Differential Equations



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