Teach the Earth > Petrology > Teaching Activities > Calculating a Simple Phase Diagram: Diamond=Graphite

# Calculating a Simple Phase Diagram: Diamond=Graphite

Dexter Perkins
,
University of North Dakota
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This activity was selected for the On the Cutting Edge Exemplary Teaching Collection

Resources in this top level collection a) must have scored Exemplary or Very Good in all five review categories, and must also rate as “Exemplary” in at least three of the five categories. The five categories included in the peer review process are

• Scientific Accuracy
• Alignment of Learning Goals, Activities, and Assessments
• Pedagogic Effectiveness
• Robustness (usability and dependability of all components)
• Completeness of the ActivitySheet web page

#### Summary

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.

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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.

#### 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.

## Determining whether students have met the goals

Students have met the goals of this assignment if they are able to complete the exercise accurately and completely.