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Redox and electrochemistry

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  1. Redox and electrochemistry

  2. Assigning oxidation numbers • Metals in group 1 have (+1) ox #, group 2 metals (+2) • Any single “Pure” element = 0 • Hydrogen is always (+1) except in metal hydride (-1) LiH 4. Oxygen is always (-2) exceptions: With flourine (flouide) +2 OF2 In Peroxides (-1) H2O2 • The sum of all oxidation #’s must = 0 • The sum of all Polyatomic ions must equal the charge of that ion

  3. Assigning oxidation numbers • Binary Compounds _____ 1. Start with the Non Metal 2. Finish with the Metal HCl 3. Sum up must = 0 _______ MgCl

  4. Assigning oxidation numbers • Ternary Compounds _____ 1. Start with the Non Metal (Oxygen) H2SO4 2. Go to the Metal (H) 3. finish up in the middle 4. Sum up must = 0 __________ Mg(NO3)2

  5. Redox Reactions(reactions where both Oxidation and Reduction take place) The gain of Electrons Half Reaction 2e- + Mg+2 Mg0 (reactant) Loss of Electrons Half Reactions Mg0 Mg+2 + 2e- (product) Leo says ger Oil rig Causes the Reduction of the other elements Acts as a REDUCING AGENT (R.A.) Causes the other species to be Oxidized. Acts as the Oxidation Agent (O.A.) 1. Oxidation Reduction

  6. Writing half reactionsdetermine the Ox / redra / oa Steps (Now this is Doc’s Method! …..Capisco?) 1. Assign the Ox #’s 2. Record the changes 3. Record e- loss / e- gain 4. Determine the species that is oxidized (RA) and reduced (OA) 5. Balance if unequal Ca + Cl2 CaCl2 ***HHH___ All Redox Reactions must demonstrate conservation of both Mass and Charge

  7. Electrochemical cellSpontaneous cell (battery)Voltaic cell, galvanic cell(****Chemical energy  electrical ****) Al Cu

  8. Electrochemical cellSpontaneous cell (battery)Voltaic cell, galvanic cell

  9. Electrochemical cellSpontaneous cell (battery)Voltaic cellgalvanic cell

  10. Electrochemical cellSpontaneous cell (battery)Voltaic cellgalvanic cell

  11. Electrochemical cellSpontaneous cell (battery)Voltaic cell, galvanic cell

  12. Electrolytic cellnon-spontaneous cell (need a power source)electroplatingelectrolysis(****electrical  chemical energy****)

  13. Electrolytic cellnon-spontaneous cell (need a power source)electroplatingelectrolysis (****electrical  chemical energy****)

  14. Electrolytic cellnon-spontaneous cell (need a power source)electroplatingelectrolysis of water!!!

  15. Electrolytic cellnon-spontaneous cell (need a power source)electrolysis of water!!! 2H2O  2H2 + O2

  16. Electrolytic cellnon-spontaneous cell (need a power source)electroplatingelectrolysis of water!!!

  17. Electrolytic cellnon-spontaneous cell (need a power source)(separation of a fused salt) 2NaCl  2Na + Cl2