1. 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)

2. 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)

3. 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)

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

5. 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 ↓)

6. 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)

7. 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

8. 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

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

10. Quick Quiz.
2. Which element is reduced in the following chemical reaction?
Fe2O CO  2 Fe CO2 O Fe C
none (not redox) +2 –2 +3 –2 +4 –2