Chem Chap 10

• Redox Reaction

  Redox : Oxidation + Reduction

  • Happens at the same time

  2 Versions:

  • Gaining/losing oxygen
  • Gaining/losing electrons
• Redox & Oxygen

  When there's oxygen in given equation

  • Oxidation : Oxygen is gained
  • Reduction : Oxygen is lost

  eg:

  • Oxi : 2Mg + O2 ---> 2MgO
  • Redu : CuO + H2 ---> Cu + H2O
• Redox & Electron Transfer


  When there's NO oxygen

  • Electrons move between atoms
  • Reduction : GAIN electrons
  • Oxidation : LOSE electrons

  Atoms/Ions = 0 charge

  Compunds = +/- so its 0 charge
• OIL RIG

  • O : Oxidation
  • I : Is
  • L : Losing electrons

  &

  • R : Reduction
  • I : Is
  • G : Gaining electrons

  If a substance...

  • Loses electrons - oxidized
  • Gains electrons - reduced
• Full equations

  1. Based on half equations
  2. Oxidized + Reduced (before) ---> Oxidized + Reduced (after)

  eg:

  • Zn + Cu (2+) ---> Zn (2+) + Cu

  MUST write after the half equations
• Half equations

  1. Identify oxidized & reduced elements
  2. Make them their own equation
  3. Oxidized : Write new one + electrons lost AFTER arrow
  4. Reduced : Write current + electrons gained BEFORE arrow

  eg:

  • Oxi: 2Mg ---> 2Mg (+2) + 4e^-1
  • Redu: O2 + 4e^-1 ---> 2O2 (2-)

  Rules(?):

  • Write the element's actual charge
  • Ignore the #__ or __#
• Oxidizing Agent

  A.k.a Oxidant

  • Oxidation state: decreases
  • Gains electrons
  • Substance is: reduced
• Reducing Agent

  A.k.a Reductant

  • Oxidation state: increases
  • Loses electrons
  • Substance is: oxidized
• Redox Color Tests

  Oxidant: Potassium Iodide

  • Colorless ---> Yellow-brown
  • Iodine Ion (1-) ---> Iodine2

  Reductant: Acidified Potassium Maganate(VII)

  • Purple ---> Colorless
  • Potassium (7+) ---> Potassium (2+)
  • MUST put ' acidified '