Phase Diagrams and Chemographic Projections

Dexter Perkins

University of North Dakota

This activity is part of the On the Cutting Edge Peer Reviewed Teaching Activities collection. (view details)

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Initial Publication Date: July 17, 2008 | Reviewed: September 26, 2013 (see revision history: 2 events)

Summary

This exercise is a good way to get students thinking about the phase rule, metastable and stable reactions and phase diagrams. It can be done in class or as homework.

Thermodynamics and Phase Equilibria, PTt Relationships | College Lower (13-14), College Upper (15-16)

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Context

Audience

Undergraduate Petrology class.

Skills and concepts that students must have mastered

Prior to assigning this, instructors should introduce the phase rule, discuss mineral equilibria in general, and explain the basics of phase diagrams. But leave the details for the students to figure out.

How the activity is situated in the course

The whole Petrology class is built around projects and exerecises. This is one of them.

Goals

Content/concepts goals for this activity

After completing this, students should:
-Better understand the phase rule
-Be able to explain why some reactions are metastable and why some reaction lines on phase diagrams stop when they hit others
-Plot mineral compositions on a triangular diagram
-Be able to apply the phase rule
-Be able to use a phase diagram to determine the PT conditions at which a given assemblage formed

Higher order thinking skills goals for this activity

This project involves visualization and interpretation of diagrams.

Other skills goals for this activity

We do this as a group project.

Description of the activity/assignment

This exercise is a good way to get students thinking about the phase rule, metastable and stable reactions and phase diagrams. The exercise contains a lot of reading, and is suitable for in-class work or for homework. The idea is that students can do this on their own with little help from their instructor.
The students only answer a few questions making this is more of a tutorial than a worksheet.

Determining whether students have met the goals

The goal is simply to complete the project. This is a learning exercise, not something that needs to be graded.

More information about assessment tools and techniques.

Teaching materials and tips

Activity Description/Assignment (Acrobat (PDF) 359kB Jan17 06)