Schreinemakers Analysis - Problem #3: Analysis of an Invariant Point (Mg-Zo-An-Gr-Pr-Ky)

Dexter Perkins
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University of North Dakota
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Summary

This is a challenging Schreinemakers analysis problem.

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Context

Audience

I use this in my Petrology class as either an in-class exercise or as homework. It is NOT simple for some students and, so, may be best done in a group.

Skills and concepts that students must have mastered

They need to know the basic Schreinemakers process and logic. They also need to be able to identify and balance reactions in a complex system. (I let them use a Gauss-Jordan-Reduction program for this purpose.)

How the activity is situated in the course

My petrology class is a studio class and so group activities and in-class work are key. This is one of many exercises the students do during the semester.

Goals

Content/concepts goals for this activity

The goal is to get them to (1) be able to do a Schreinemakers analysis, and (2) understand the significance of invariant points and stable/metastable equilibria.

Higher order thinking skills goals for this activity

Thinking, logic, reasoning, and deduction are involved. -- this problem sometimes stumps students who are looking for a cookbook approach. Accuracy and care are essential.

Other skills goals for this activity

They need to be able to identify and balance reactions in a complex system. (I let them use a Gauss-Jordan-Reduction program for this purpose.)

Description of the activity/assignment

This is a standard Schreinemakers problem: identifying the sequence of stable and metastable reactions around an invariant point. However, this problem deals with a 4-component system and phases of complex chemistry. So, Identifying and balancing the reactions is not trivial and can be a real challenge for some students.

Determining whether students have met the goals

There are two possible results (mirror images) and it is simple to determine if students obtain one of them.

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Teaching materials and tips

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