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Science Dept.

Chemistry CHE 100 Notes
S. Redox

1. Definitions
   1. Redox: Trading of electrons, e^-

   2. Oxidation Number: is a whole number used to describe the combining capacity of an element in a compound with a + or - assigned

   3. Oxidation: Loss of electrons, an increase in oxidation number
      1. Fe²⁺ to Fe³⁺

      2. S^2- to S⁶⁺

   4. Reduction: Gain of electrons, a decrease in oxidation number
      1. Fe³⁺ to Fe²⁺

      2. S⁶⁺ to S^2-

   5. Oxidation Accompanies Reduction
      1. N.B.: When a substance is oxidized some other substance is reduced

   6. Oxidizing Agent
      1. Oxidizes a substance

      2. The oxidizing agent is reduced

   7. Reducing Agent
      1. Reduces a substance

      2. The reducing agent is oxidized

2. Electrolytic Cells
   1. Use electrical energy to produce certain chemical reactions

   2. For Example, electroplating

   3. General Reactions
      1. Reduction Reactions at the Cathode: X¹⁺ + 1e^1- ----> X^o

      2. Oxidation Reactions at the Anode: Y^1- ----> 1e^1- + Y^o

   4. For Electroplating
      1. Reduction Reactions at the Cathode: Ag¹⁺ + 1e^- ----> Ag^o

      2. Oxidation Reactions at the Anode: Ag^o ----> Ag¹⁺ + 1e^-

   5. Construct a diagram of an Electolytic Cell

3. Voltaic or Galvanic Cells
   1. Produce electrical energy from certain chemical reactions

   2. For example, a battery

   3. Reactions named after Alessandro Volta and Liugi Galvani

   4. Reactions
      1. The total reaction: Zn^o + Cu²⁺ ----> Zn²⁺ + Cu^o

      2. Reduction Reactions at the Cathode: Cu²⁺ +2e^- ---->Cu^o

      3. Oxidation Reactions at the Anode: Zn^o ---->Zn²⁺ + 2e^-

   5. Construct a diagram of a Voltaic Cell

    
   

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