Schreinemakers Analysis - Problem #4

Dexter Perkins
University of North Dakota
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Initial Publication Date: August 22, 2007 | Reviewed: August 2, 2011


This is a straightforward Schreinemakers analysis involving two invariant points.

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I use this in my Petrology class as an in-class activity.

Skills and concepts that students must have mastered

Students must understand the phase rule, the basics of Schreinemakers analysis, and they must be able to derive and balance reactions.

How the activity is situated in the course

I use this as a group activity. It is the first Schreinemakers problem the students do.


Content/concepts goals for this activity

The goal is for them to be able to do basic Schreinemakers analyses. This is not a very complicated problem.

Higher order thinking skills goals for this activity

Other skills goals for this activity

Description of the activity/assignment

Students start with three reaction curves and determine which intersections are invariant points. Then they derive the other two missing reactions and draw them on the PT diagram in the correct places. Finally, they identify the parts of the curves that are stable and metastable.

Determining whether students have met the goals

We discuss this after all students have completed it. There is only one correct topology, but the slopes of the curves are not constrained so all students will not get identical results.

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