1. Section 2: Redox Reactions
A. Redox Rxns
B. Redox in Living Systems

2. A. Redox Rxns
Redox Rxns: oxidation-reduction reactions involving the transfer of electrons
(e- loss & e- gain)
OILRIG

3. A. Redox Rxns
used to be gaining oxygen
2 Fe(s)
+ 3 O2(g)
→ Fe2O3(s)

4. A. Redox Rxns

5. A. Redox Rxns

6. CH4(g) + 2O2(g) → CO2(g) + H2O(g)
A. Redox Rxns -4 +1 +4 -2 +1 -2
CH4(g)
+ 2O2(g)
→ CO2(g)
+ H2O(g)
Oxidized? (charge ↑)
Reduced? (charge ↓)

7. NOT REDOX because… (NO e- loss or gain) A. Redox Rxns 2NaF(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)

8. water (H2O) is oxidized to oxygen (O2)
B. Redox in Living Systems
Photosynthesis
water (H2O) is oxidized to oxygen (O2) +4 -2 +1 -2 +1 -2
6CO2
+ 6H2O
→ C6H12O6
+ 6O2
carbon dioxide (CO2) is reduced to glucose (C6H12O6)

9. B. Redox in Living Systems
Cellular Respiration
C6H12O6 is oxidized to CO2 +1 -2 +4 -2 +1 -2
C6H12O6
→ 6CO2
+ 6O2
+ 6H2O
O2 is reduced to H2O

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

11. 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 -2 +3 +4 -2