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10: Reduction and Oxidation Chemistry

  • Page ID
    469955
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    Learning Objectives

    • Balance a redox reaction in acidic or basic solution
    • Calculate the cell potential and free energy of an electrochemical cell under standard and non-standard conditions
    • Use Latimer diagrams to determine unknown reduction potential values and to quickly identify stable and unstable species
    • Use Frost diagrams to determine which oxidation states of a species are stable and which are unstable
    • Use Porbaix diagrams to determine which species will be present in solution under given conditions

    Thumbnail image shows the Porbaix diagram of chromium (CC BY-SA 3.0, Denis Zhilin via Wikimedia Commons)

    • 10.1: Review of Redox Chemistry
      An electric current consists of moving charge. The charge may be in the form of electrons or ions. Current flows through an unbroken or closed circular path called a circuit. The current flows through a conducting medium as a result of a difference in electrical potential between two points in a circuit. Electrical potential has the units of energy per charge. In SI units, charge is measured in coulombs (C), current in amperes, and electrical potential in volts.
    • 10.2: Oxidation States of Transition Metals
      The oxidation state of an element is related to the number of electrons that an atom loses, gains, or appears to use when joining with another atom in compounds. It also determines the ability of an atom to oxidize (to lose electrons) or to reduce (to gain electrons) other atoms or species. Almost all of the transition metals have multiple potential oxidation states.
    • 10.3: Electrochemical Potentials
      In electrochemical cells, or in redox reactions that happen in solution, the thermodynamic driving force can be measured as the cell potential. Chemical reactions are spontaneous in the direction of -ΔG, which is also the direction in which the cell potential is positive
    • 10.4: Latimer Diagrams
      Latimer diagrams helpfully summarize elements' redox chemistry in a compact visual format.
    • 10.5: Frost Diagrams
      Frost diagrams represent how stable an elements' redox states are relative to the free element. In a Frost diagram a proxy for the free energy relative to that of the free element (oxidation state zero) is plotted as a function of oxidation state.
    • 10.6: Pourbaix Diagrams
      Pourbaix Diagrams plot electrochemical stability for different redox states of an element as a function of pH. As noted above, these diagrams are essentially phase diagrams that plot the map the conditions of potential and pH (most typically in aqueous solutions) where different redox species are stable. Typically, the water redox reactions are plotted as dotted lines on these more complicated diagrams for other elements.
    • 10.7: Exercises
      These are homework exercises to accompany the Textmap created for "Chemistry" by OpenStax. Complementary General Chemistry question banks can be found for other Textmaps and can be accessed here. In addition to these publicly available questions, access to private problems bank for use in exams and homework is available to faculty only on an individual basis; please contact Delmar Larsen for an account with access permission. Exercises 51-60 were added with support fro OpenAI. (2024). ChatGPT


    10: Reduction and Oxidation Chemistry is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts.

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