**Unit 7: Phase Changes and Phase Equilibria**
*Phase changes deal with physical transformations of pure substances. An
important kind of equilibrium is one in which the pure substance exists
in two or more states of matter. We exploit this property in many ways
in all branches of science. For example, in chemistry experiments we
often freeze cells in liquid nitrogen vapor, which is in equilibrium
with its liquid in the storage tank. In this unit, you will learn how to
generate phase diagrams and perform calculations related to energy
requirements for phase changes.*

**Unit 7 Time Advisory**

Completing this unit should take approximately 17 hours.

☐ Subunit 7.1: 8 hours

☐ Subunit 7.2: 5 hours

☐ Subunit 7.3: 3 hours

☐ Subunit 7.4: 1 hour

**Unit7 Learning Outcomes**

Upon successful completion of this unit, you should be able to:

- describe the different phases of matter and the changes between
them;
- calculate the thermodynamic functions ΔH, ΔS, and ΔG for phase
changes;
- interpret and construct phase diagrams for single- and
multiple-component systems;
- state and derive the Clausius-Clapeyron equation; and
- describe the similarities and differences between reaction and phase
equilibria.

**7.1 A Review of Phase Changes**
- **Lecture: Academic Earth: The University of California at Berkeley:
Dr. Angelica Stacy’s “It’s Just a Phase: Phase Changes”**
Link: Academic Earth: The University of California at Berkeley: Dr.
Angelica Stacy’s “It’s Just a Phase: Phase
Changes” (Adobe
Flash)

```
Instructions: Watch the video (approximately 52 minutes in length)
to learn about the different phases of matter and the conditions
under which they may co-exist or transform into one another.
Watching this lecture should take approximately 1 hour.
Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.
```

**Reading: Institute of Chemical Technology, Prague: Ing. Anatol Malijevský, CSc. et al.’s**Link: Institute of Chemical Technology, Prague: Ing. Anatol Malijevský, CSc. et al.’s*Physical Chemistry in Brief*: “Chapter 7: Phase Equilibria”*Physical Chemistry in Brief*: “Chapter 7: Phase Equilibria” (PDF)Instructions: Read chapter 7, titled “Phase equilibria,” beginning on page 171 and ending on page 225. In this reading, you will encounter a systematic development of the thermodynamic principles that govern phase equilibria in physical systems, as well as a description of the thermodynamic properties associated with changes in phase. Be sure to carefully review all the diagrams and example problems presented in this reading.

Reading this material should take approximately 3 hours.

Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

**Reading: Dr. Howard DeVoe’s**Link: Dr. Howard DeVoe’s*Thermodynamics and Chemistry*(2nd ed.): “Chapter 8: Phase Transitions and Equilibria of Pure Substances”*Thermodynamics and Chemistry*(2^{nd}ed.): “Chapter 8: Phase Transitions and Equilibria of Pure Substances” (PDF)Instructions: Navigate to chapter 8, beginning on page 193, and read the chapter, ending on page 222. Be sure to work through all the exercises and problems provided throughout the chapter. Focus on understanding the physical basis and mathematical formulation of all the expressions given in the chapter. There is no need to develop a facility for deriving all the equations, but you should be able to identify when and where the various equations are applicable as well as be able to use them in performing calculations.

Reading this material should take approximately 4 hours.

Terms of Use: This resource is licensed under a Creative Commons Attribution-NonCommercial-NoDervis 3.0 Unported License.

**7.2 Phase Equilibria: One-Component Systems**
- **Lecture: Lecture: Massachusetts Institute of Technology
OpenCourseWare: Dr. Moungi Bawendi and Dr. Keith Nelson’s “Lecture
18: Phase Equilibria – One Component”**
Link: Massachusetts Institute of Technology OpenCourseWare: Dr.
Moungi Bawendi and Dr. Keith Nelson’s “Lecture 18: Phase Equilibria
– One
Component”

```
Also available in:
[iTunesU](http://ocw.mit.edu/courses/chemistry/5-60-thermodynamics-kinetics-spring-2008/video-lectures/lecture-18-phase-equilibria-2014-one-component/)
[MP4](http://ocw.mit.edu/courses/chemistry/5-60-thermodynamics-kinetics-spring-2008/video-lectures/lecture-18-phase-equilibria-2014-one-component/)
Instructions: Watch the video (approximately 51 minutes in length)
to learn about phase changes—first in one-component systems and then
in multiple-component systems. Phase changes are little bit
different from chemical reactions; there are some different results
and different equations that we use to describe them. You can find
the lecture notes for this video here (PDF).
Watching this lecture should take approximately 1 hour.
Terms of Use: This resource is licensed under a [Creative Commons
Attribution-NonCommercial-ShareAlike 3.0 United States
license](http://creativecommons.org/licenses/by-nc-sa/3.0/us/).
```

**Reading: The University of Windsor:**Link: The University of Windsor:*Introductory Physical Chemistry*: Dr. Rob Schurko’s Course Notes: “Lecture 14: Physical Transformations of Pure Substances” and “Lecture 15: Phase Transitions & Interfaces”*Introductory Physical Chemistry*: Dr. Rob Schurko’s Course Notes: “Lecture 14: Physical Transformations of Pure Substances”and “Lecture 15: Phase Transitions & Interfaces” (PDF)Instructions: Read Dr. Schurko’s course material. As you read, pay special attention to the diagrams and figures presented in both sets of notes. Also, be sure to carefully review the equations that give the mathematical representations relevant to the thermodynamic data displayed in the figures.

Reading this material should take approximately 4 hours.

Terms of Use: Please respect the copyright and terms of use displayed on the webpages above.

**7.3 Clausius-Clapeyron Equation**
*Note: Some of the material you need to know for this subunit is covered
by the* *Malijevský and DeVoe readings assigned beneath Subunit 7.1 of
this course.*

**Lecture: Massachusetts Institute of Technology OpenCourseWare: Dr. Moungi Bawendi and Dr. Keith Nelson’s “Lecture 19: Clausius-Clapeyron Equation”**Link: Massachusetts Institute of Technology OpenCourseWare: Dr. Moungi Bawendi and Dr. Keith Nelson’s “Lecture 19: Clausius-Clapeyron Equation”Also available in:

Instructions: Watch the video (approximately 50 minutes in length) on the Clausius-Clapeyron equation. This equation helps us to construct the phase diagram of a single-component system with two phases. You can find the lecture notes for this video here (PDF).

Watching this lecture should take approximately 1 hour.

Terms of Use: This resource is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States license.

**Reading: The University of Arizona: Professor W.R. Salzman’s**Link: The University of Arizona: Professor W.R. Salzman’s*“Dynamic Textbook” of Physical Chemistry*: “Clapeyron and Clausius-Clapeyron Equations”*“Dynamic Textbook” of Physical Chemistry*: “Clapeyron and Clausius-Clapeyron Equations” (HTML)Instructions: Read the webpage and work through the equations presented on the webpage. This resource will help you understand how the Clapeyron and Clausius-Clapeyron equations are derived from the combined first and second laws of thermodynamics, and how these equations are used to ascertain the conditions for phase equilibria and the details of phase diagrams.

Reading this material should take approximately 2 hours.

Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

**7.4 Phase Equilibria: Two-Component Systems**
*Note: Some of the material you need to know for this subunit is covered
by the* *Malijevskýand DeVoe readings assigned beneath Subunit 7.1 of
this course.*

**Lecture: Massachusetts Institute of Technology OpenCourseWare: Dr. Moungi Bawendi and Dr. Keith Nelson’s “Lecture 20: Phase Equilibria – Two Components”**Link: Massachusetts Institute of Technology OpenCourseWare: Dr. Moungi Bawendi and Dr. Keith Nelson’s “Lecture 20: Phase Equilibria – Two Components”Also available in:

Instructions: Watch the video (approximately 50 minutes in length) to learn about equilibrium in multi-component systems. You can find the lecture notes for this video here (PDF).

Watching this lecture should take approximately 1 hour.Terms of Use: This resource is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States license.