Chapter 10.1: Defining Oxidation and Reduction

• Ore: naturally occurring solid compound or mixture of compounds from which a metal can be extracted

• Oxidation: loss of electrons, “oxidized”

• Reduction: gain of electrons “reduced”

• Oxidation-reduction reaction/ redox reaction: oxidation and reduction both occur in the reaction

• Oxidizing agent: a reactant that oxidizes another reactant

  • Accepts electrons

• Reducing agent: a reactant that reduces another reactant

  • Gives or donates electrons

• Half-reaction: a balanced equation that shows the number of electrons involved in either oxidation or reduction

  • Half-reactions can be added to make a redox reaction

• Disproportionation: a ****single element undergoes both oxidation and reduction

  • Ex. 2 Cu+(aq) → Cu(s) + Cu2+(aq)

Chapter 10.2: Oxidation Numbers

• Oxidation numbers: actual or hypothetical charges, assigned using a set of rules

  • Describe redox reactions with covalent reactants or products

  • Help identify redox reactions and the oxidizing and reducing agents

  • Lewis structure can help find oxidation numbers but memorizing rules reduces time drawing lewis structures

    • Pure element: 0

    • Element in a monatomic ion: equals charge of ion

    • Hydrogen

      • In compounds: +1

      • Metal hydrides: -1

    • Oxygen

      • Usually: -2

      • Peroxides are exceptions

    • Covalent compound with no hydrogen or oxygen

      • Most electronegative lament is assigned oxidation number equal to its ion charge

      • Sum of oxidation numbers in element in a compound equal to 0

      • Sum of oxidation numbers in a polyatomic ion equal to the charge of the ion

  • Oxidation: increase in oxidation number

  • Reduction: decrease in oxidation number

Chapter 10.3: The Half-Reaction Method for Balancing Equations

• K→ K+ +e−

  • The net charge on each side is 0

  • Ions must be taken into the present for H+ or OH−

• To balance the net ionic equation for redox reaction number of electrons lost through oxidation must equal the number of electrons gained through the reduction

• Find the LCM (least common multiple) of the number of electrons and multiply by coefficients

Chapter 10.4: The Oxidation Number Method for Balancing Equations

• Oxidation number method: method of balancing redox equations by ensuring that the total increase in the oxidation numbers of the oxidized element(s) equals the total decrease in the oxidation numbers of the reduced element(s)

• Steps of oxidation number method:

  • Write unbalanced equation if not given

  • Assign oxidation numbers to each element to find if it is a redox reaction

  • Identify elements undergoing oxidation or reduction if it is a redox reaction

  • Determine the smallest whole number of redox elements so total oxidation numbers equal to the total decrease in oxidation numbers

  • Use smallest whole ratio to balance atoms of elements oxidized and elements reduced

  • Balance other elements by inspection

  • Include water molecules, hydrogen ions, hydroxide ions for acidic/basic solutions