Calculating a Simple Phase Diagram: Diamond=Graphite

Dexter Perkins

University of North Dakota

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Initial Publication Date: June 8, 2008 | Reviewed: October 18, 2012 (see revision history: 2 events)

Summary

Phase Equilibria/Thermodynamics, Thermodynamics and Phase Equilibria, ...(more) | College Lower (13-14), College Upper (15-16)

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Context

Audience

This exercise is used in a sophomore or junior level required course in petrology.

Skills and concepts that students must have mastered

Students should have an understanding of Gibbs energy.

How the activity is situated in the course

This activity is a stand-alone exercise.

Goals

Content/concepts goals for this activity

This exercise is designed to get students to understand how the Gibbs energy equation is used to calculate the location of a reaction in P-T space.

Higher order thinking skills goals for this activity

Other skills goals for this activity

This activity may involve group work.

Description of the activity/assignment

This is a very short exercise designed to get students to understand how the Gibbs energy equation is used to calculate the location of a reaction in P-T space. I use it in-class and have students work on it in groups.

Besides calculating the location of one reactions, students also have to think a bit about the significance of volume and entropy with regard to mineral stability.

This exercise is very straightforward EXCEPT that students get the units (bars, Kbar, cc, etc.) confused.