Oxidation and Reduction Reactions
(REDOX Rxns)
video clip
Redox Rxns:
oxidation-reduction rxns transfer e–’s
LEO
says
GER
Oxidation: Reduction:
• gain e–
• lose e–
• charge ↑ • charge ↓
0
0 0
0 0
0
0
00
0
0
REDOX:
• transfer e–
00
–2 +3 –2
–2 +3
+3
–2
4 Fe(s) + 3 O2(g) → 2 Fe2O3(s)
Metals: tend to be oxidized (lose e–)
Nonmetals: tend to be reduced (gain e–)
magnesium
0
0
0
0 0
0
0
Mg(s) +
0
→
+2–2
+2–2
+2 –2
Metals: tend to be oxidized (lose e–)
Nonmetals: tend to be reduced (gain e–)
LEO
says
GER
0
0
+2 –2
-4 +1
0
+4 -2
+1 -2
CH4(g) + O2(g) → CO2(g) + H2O(g)
Oxidized? (charge ↑)
Reduced? (charge ↓)
+2 -1
+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
0
+1
–2
0
6CO2 + 6H2O → C6H12O6 + 6O2
C+4 is reduced to C0
Redox in Living Systems
Cellular Respiration
C0 is oxidized to C+4
0
+1
–2
0
+4 –2
+1
–2
C6H12O6 + 6O2 → 6CO2 + 6H2O
O0 is reduced to O–2
Quick Quiz!
1. During oxidation, an element
_______ electrons. During reduction,
an element ________ electrons.
A.
B.
C.
D.
gains, loses
loses, gains
gains, donates
gains, accepts
Quick Quiz.
2. Which element is reduced in the
following chemical reaction?
+3 –2
+2 –2
0
+4 –2
Fe2O3 + 3 CO  2 Fe + 3 CO2
A.
B.
C.
D.
O
Fe
C
none (not redox)