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CHEM202: Advanced Inorganic Chemistry

Unit 7: Oxidation and Reduction Chemistry  

One of the most unique properties of transition metals is their ability to take multiple oxidation states.  This ability is extremely important in reaction mechanisms, such as the “oxidative addition” or “reductive elimination” of ligands, which will be discussed in the next unit.  Oxidation states are also critical in determining the total electron count, geometrical shape, and magnetic properties of the metal complexes.  In fact, the reactivity of transition metals and their metal complexes is highly dependent on their oxidation states and redox properties.  Biologically important molecules utilize these abilities, especially in enzymes.  For example, iron usually has a +2 or +3 charge; however, it has been observed as a +4 or even +5 charge in the transition state of methane monooxygenase.  You will learn about these exceptions in your bioinorganic chemistry course.

Unit 7 Time Advisory
This unit should take you approximately 13 hours to complete.

☐    Subunit 7.1: 9.0 hours
 

☐    Introduction: 5.0 hours

☐    Sub-subunit 7.1.1: 2.0 hours

☐    Sub-subunit 7.1.2: 2.0 hours
 

☐    Subunit 7.2: 2.0 hours

☐    Subunit 7.3: 2.0 hours  

Unit7 Learning Outcomes
Upon successful completion of this unit, the student will be able to:

  • Balance half-reactions of redox processes in neutral, acidic, and alkaline media.
  • Discuss the kinetic factors of electron transfer, specifically inner-sphere and outer-sphere electron transfer.
  • Interpret information obtained from Frost diagrams, Latimer diagrams, and Pourbaix diagrams, and predict predominant redox species given specific conditions.
  • Explain Marcus theory of electron transfer and dicuss electron transfer reactions.

7.1 Reduction-Oxidation Reactions (Redox)   - Reading: Jim Clark’s Chemguide: “Definitions of Oxidation and Reduction (Redox)” Link: Jim Clark’s Chemguide:  "Definitions of Oxidation and Reduction (Redox)" (HTML)
 
Instructions: Please read the entire webpage.  This material is a review of general electrochemistry and terminology.
 
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  • Reading: Western Oregon University: Dr. Arlene Courtney’s “Diagrams That Provide Useful Oxidation-Reduction Information” Link: Western Oregon University: Dr. Arlene Courtney’s “Diagrams That Provide Useful Oxidation-Reduction Information” (HTML)
     
    Instructions: Please read the entire webpage.  This material defines what relevant information can be obtained from Latimer, Frost, and Pourbaix diagrams.            
     
    Terms of Use: Please respect the terms of use displayed on the webpage above.

  • Reading: Purdue University: George M. Bodner’s “Oxidation-Reduction Reactions” Link: Purdue University: George M. Bodner’s “Oxidation-Reduction Reactions” (HTML)
     
    Instructions: Please read the entire webpage and work the six practice problems contained within the text.  This material demonstrates how to balance redox reactions under various conditions, such as in acid or base.
     
    Terms of Use: Please respect the terms of use displayed on the webpage above. 

7.1.1 Half Reactions   - Reading: Jim Clark’s Chemguide: “Writing Ionic Equations for Redox Reactions” Link: Jim Clark’s Chemguide:  “Writing Ionic Equations for Redox Reactions” (HTML)
 
Instructions: Please read the entire webpage.  This material reviews how to balance redox reactions using the half-reaction method.  Examples 2 and 3 are quite involved but well-explained.  Please note: these reactions are done in acidic or neutral media.
 
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  • Reading: Jim Clark’s Chemguide: “Writing Ionic Equations for Redox Reactions Done Under Alkaline Conditions” Link: Jim Clark’s Chemguide:  "Wringing Ionic Equations for Redox Reactions Done Under Alkaline Conditions" (HTML)
     
    Instructions: Read the entire webpage.  This material reviews how to balance redox reactions using the half-reaction method in basic media. 
     
    Terms of Use: Please respect the terms of use displayed on the webpage above.

7.1.2 Kinetic factors (Outer Sphere and Inner Sphere Electron Transfer)   - Reading: University of Rhode Island’s “Chemistry 401: Kinetic Considerations” Link: University of Rhode Island’s “Chemistry 401: Kinetic Considerations” (HTML)
 
Instructions: Please read the entire webpage.  This material discusses overpotentials and mechanisms of electron transfers.  Simply stated, this helps explain why a reaction may not proceed even though it is energetically favored. 
 
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7.2 Pourbaix Diagrams   - Reading: Western Oregon University: Dr. Arlene Courtney’s “Pourbaix Diagrams” Link: Western Oregon University: Dr. Arlene Courtney’s "Pourbaix Diagrams" (HTML)
 
Instructions: Please read the entire webpage.  This material dissects Pourbaix diagrams, which are used to predict the dominant ionic species given certain conditions.  Please work the four example problems found in the body of the text to ensure that you understand how to read these types of diagrams.
 
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7.3 Marcus Theory of Electron Transfer   - Reading: University of Oxford: Dr. Dermot O’Hare’s “Lecture 3: Electron Transfer Reactions” Link:  University of Oxford: Dr. Dermot O’Hare’s “Lecture 3: Electron Transfer Reactions” (HTML)
 
Instructions: Please use the “next page” link in the upper right corner to navigate through the slides.  The presentation covers the first part of a lecture on electron transfer reactions.
 
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  • Reading: University of Oxford: Dr. Dermot O'Hare's “Lecture 4” Link:  University of Oxford: Dr. Dermot O'Hare's "Lecture 4" (HTML)
     
    Instructions: Use the “next page” link in the upper right corner to navigate through the slides.  The presentation continues the lecture on electron transfer reactions.
     
    Terms of Use: Please respect the terms of use displayed on the webpage above.