Oxidation and Reduction Reactions (REDOX Rxns) video clip Redox Rxns: oxidation-reduction rxns transfer e–’s LEO says GER video clip – Zn and O2 redox (2 min)

4 Fe(s) + 3 O2(g) → 2 Fe2O3(s) Oxidation: lose e– charge ↑ Reduction: gain e– charge ↓ REDOX: transfer e– –2 +3 –2 –2 used to be gaining oxygen +3 +3 –2 4 Fe(s) + 3 O2(g) → 2 Fe2O3(s)

Mg(s) + S(s) → MgS(s) Metals: tend to be oxidized (lose e–) Nonmetals: tend to be reduced (gain e–) magnesium magnesium sulfide sulfur +2 –2 +2 –2 +2 –2 Mg(s) + S(s) → MgS(s)

LEO says GER Metals: tend to be oxidized (lose e–) Nonmetals: tend to be reduced (gain e–) LEO says GER +2 –2

CH4(g) + O2(g) → CO2(g) + H2O(g) -4 +1 +4 -2 +1 -2 CH4(g) + O2(g) → CO2(g) + H2O(g) Oxidized? (charge ↑) Reduced? (charge ↓)

NOT REDOX because… (NO e– loss or gain) 2NaF(aq) + CaCl2(aq) -1 +2 -1 +1 +1 -1 +2 -1 2NaF(aq) + CaCl2(aq) → 2NaCl(aq) + CaF2(s) Oxidized? (charge ↑) Reduced? (charge ↓) NOT REDOX because… NO charges changed (NO e– loss or gain)

Redox in Living Systems Photosynthesis O–2 is oxidized to O20 +4 –2 +1 –2 +1 –2 6CO2 + 6H2O → C6H12O6 + 6O2 C+4 is reduced to C0

Redox in Living Systems Cellular Respiration C0 is oxidized to C+4 +1 –2 +4 –2 +1 –2 C6H12O6 → 6CO2 + 6O2 + 6H2O O0 is reduced to O–2

Quick Quiz! 1. During oxidation, an element _______ electrons. During reduction, an element ________ electrons. gains, loses loses, gains gains, donates gains, accepts

Quick Quiz. 2. Which element is reduced in the following chemical reaction? Fe2O3 + 3 CO  2 Fe + 3 CO2 O Fe C none (not redox) +2 –2 +3 –2 +4 –2