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CHEM105: Physical Chemistry I

Unit 8: Thermodynamic Properties of Solutions   A solution is a homogeneous mixture comprising two or more substances that are mutually miscible. Common examples of solutions include Earth’s atmosphere, salt water, alcoholic beverages, and many metallic alloys. Compound materials that are not solutions include milk, precipitate-hardened alloys, and carbon-fiber composites. The special thermodynamic properties of solutions reflect large entropic contributions from the atomic or molecular-level disorder that characterizes most homogeneous solutions. The thermodynamic behavior of solutions is, in large part, dominated by entropic effects. In this unit we will identify the thermodynamic driving forces that govern the formation and stability of solution media. We also will show how the thermodynamic properties of a solution reflect the physical properties and interaction dynamics of the molecular constituents of the solution. 

Unit 8 Time Advisory
Completing this unit should take approximately 14 hours.

☐  Subunit 8.1: 4 hours
☐  Subunit 8.2: 3 hours
☐  Subunit 8.3: 4 hours
☐  Subunit 8.4: 3 hours

Unit8 Learning Outcomes
Upon successful completion of this unit, you should be able to: - define and describe ideal and real solutions; - state Raoult’s law and Henry’s law, and use these laws to calculate solution properties; - define what is meant by the term colligative property; - calculate the freezing point depression, boiling point elevation, and osmotic pressure of solutions with dissolved solutes; - calculate the thermodynamic functions associated with mixing; - define surface tension and capillary action; and - describe the molecular interactions at liquid-gas and liquid-liquid interfaces.

8.1 Ideal Solutions   - Lecture: Massachusetts Institute of Technology OpenCourseWare: Dr. Moungi Bawendi and Dr. Keith Nelson’s “Lecture 21: Ideal Solutions” Link: Massachusetts Institute of Technology OpenCourseWare: Dr. Moungi Bawendi and Dr. Keith Nelson’s “Lecture 21: Ideal Solutions”

 Also available in:  

[iTunesU](http://ocw.mit.edu/courses/chemistry/5-60-thermodynamics-kinetics-spring-2008/video-lectures/lecture-21-ideal-solutions/)  

[MP4](http://ocw.mit.edu/courses/chemistry/5-60-thermodynamics-kinetics-spring-2008/video-lectures/lecture-21-ideal-solutions/)  

 Instructions: Watch the video (approximately 50 minutes in length)
to learn about ideal solutions and their associated vapor pressures.
Raoult’s law and Henry’s law also are presented in this lecture.
Raoult’s law applies to the partial vapor pressure of the *solvent*
component of a solution in the limit of infinite dilution, whereas
Henry’s law applies to the partial vapor pressure of the *solute*
component of a solution in the limit of infinite dilution. Observed
deviations from Raoult’s law and Henry’s law behavior provide
diagnostics of solute-solvent interactions in solution media. 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 Arizona: Professor W.R. Salzman’s “Dynamic Textbook” of Physical Chemistry: “Open Systems” and “Mixtures; Partial Molar Quantities; Ideal Solutions” Link: The University of Arizona: Professor W.R. Salzman’s “Dynamic Textbook” of Physical Chemistry: “Open Systems”and “Mixtures; Partial Molar Quantities; Ideal Solutions” (HTML)

    Instructions: Study the material on the “Open Systems” and “Mixtures; Partial Molar Quantities; Ideal Solutions” webpages. Focus on acquiring an understanding of how the thermodynamic properties of an open, multicomponent system are dependent on the number and relative amounts of the constituent components.

    Reading this material should take approximately 3 hours.

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

  • Optional: Institute of Chemical Technology, Prague: Ing. Anatol Malijevský, CSc. et al.’s Physical Chemistry in Brief: “Chapter 6: Thermodynamics of Homogeneous Mixtures (Sections 6.1-6.4)” Link: Institute of Chemical Technology, Prague: Ing. Anatol Malijevský, CSc. et al.’s Physical Chemistry in Brief: “Chapter 6: Thermodynamics of Homogeneous Mixtures (Sections 6.1-6.4)” (PDF)

    Instructions: Read sections 6.1-6.4 (from “Ideal mixtures” through “Chemical potential,” on pages 139-157) from chapter 6 of the textbook. Please note that this reading is optional; if you choose to complete it, you are encouraged to work through all the example problems provided in the text, as these examples will help you assess your ability to apply the relevant thermodynamic principles.

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

8.2 Non-Ideal Solutions   Note: Some of the material you need to know for this subunit is covered by lecture and readings assigned beneath Subunit 8.1, found above.

  • Lecture: Massachusetts Institute of Technology OpenCourseWare: Dr. Moungi Bawendi and Dr. Keith Nelson’s “Lecture 22: Non-Ideal Solutions” Link: Massachusetts Institute of Technology OpenCourseWare: Dr. Moungi Bawendi and Dr. Keith Nelson’s “Lecture 22: Non-Ideal Solutions”

    Also available in:

    iTunesU

    MP4

    Instructions: Watch the video (approximately 51 minutes in length) to learn more about how real solutions behave. 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 “Dynamic Textbook” of Physical Chemistry: “Activity and Activity Coefficients” and “Vapor Pressure Diagrams and Boiling Diagrams” Link: The University of Arizona: Professor W.R. Salzman’s “Dynamic Textbook” of Physical Chemistry: “Activity and Activity Coefficients” and “Vapor Pressure Diagrams and Boiling Diagrams” (HTML)

    Instructions: Study the material displayed on both webpages. In this reading, you will encounter the definitions of the terms activity and activity coefficient as they are used in thermodynamic descriptions of physical systems (under equilibrium conditions).

    Reading this material should take approximately 2 hours.

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

8.3 Colligative Properties   Note: Some of the material you need to know for this subunit is covered by the lecture and readings assigned beneath Subunit 8.1, found above.

  • Lecture: Massachusetts Institute of Technology OpenCourseWare: Dr. Moungi Bawendi and Dr. Keith Nelson’s “Lecture 23: Colligative Properties” Link: Massachusetts Institute of Technology OpenCourseWare: Dr. Moungi Bawendi and Dr. Keith Nelson’s “Lecture 23: Colligative Properties”

    Also available in:

    iTunesU

    MP4

    Instructions: Watch the video (approximately 51 minutes in length). Colligative properties of solutions are those that depend only on the number of dissolved solutes and not on their chemical identity. Examples of colligative properties include freezing-point depression, boiling-point elevation, and osmotic pressure. 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 “Dynamic Textbook” of Physical Chemistry: “Colligative Properties” Link: The University of Arizona: Professor W.R. Salzman’s “Dynamic Textbook” of Physical Chemistry: “Colligative Properties” (HTML)

    Instructions: Read webpage. Be sure to work through the derivations of all the equations shown in this section. Focus on developing a facility for using the equations to calculate the colligative properties of a system under a specified set of physical conditions.

    Reading this material should take approximately 3 hours.

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

8.4 Surface Properties of Solutions   - Web Media: Purdue University Department of Chemistry’s “Surface Tension” Link: Purdue University Department of Chemistry’s “Surface Tension” (HTML)

 Instructions: Study the webpage, including the general definition
of surface tension and the animation of microscopic behavior at the
surface of a liquid. *Surface tension* is an important property of a
solution. It is defined as the amount of force needed to increase
the surface of a solution by unit area. *Capillary action* results
from surface tension and the adhesive forces between the substance
and the tube.  

 Completing this web media assignment should take approximately 30
minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.
  • Web Media: The University of Florida: Dr. Elsa Susana Sepúlveda Bustos’s “Surface Tension” Link: The University of Florida: Dr. Elsa Susana Sepúlveda Bustos’s “Surface Tension” (HTML)

    Instructions: Explore the webpage. This resource has many interesting animations, videos, and pictures to help you get an intuitive grasp of surface tension and capillary action. Be sure to watch the video of capillary action comparing two different substances in glass tubes. To find this video, navigate to the index at the top left of the webpage, then click on the section titled “Capillary Rise.” After clicking on the webpage links to view the illustrations and examples, try the three sample problems and the self-test at the bottom of the webpage.

    Completing this web media assignment 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 Physical Chemistry in Brief: “Chapter 13: Physical Chemistry of Surfaces” Link: Institute of Chemical Technology, Prague: Ing. Anatol Malijevský, CSc. et al.’s Physical Chemistry in Brief: “Chapter 13: Physical Chemistry of Surfaces” (PDF)

    Instructions: Navigate to chapter 13 of the textbook, beginning on page 436 and ending on page 455. Read the chapter. This reading provides an excellent treatment of the thermodynamic properties that are characteristic of surfaces and interfacial phenomena.

    Reading this material should take approximately 1.5 hours.

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