Oxidation and reduction deals with the transferring of electrons between reactants. The reactant that loses electrons is oxidized, while the reactant that gains electrons is reduced.
Concept #1: Understanding Oxidation versus Reduction
When in doubt about oxidation or reduction just remember the phrase: "LEO the lion goes GER."
Concept #2: Rules for Oxidation Numbers
We use these oxidation number rules whenever we are asked to determine the oxidation number of an entire compound or the individual elements within a compound.
Example #1: What is the oxidation number of each underlined element?
Instead of being asked who is oxidized or reduced, sometimes you may be asked to determine the reducing and oxidizing agents.
Example #2: In the following reaction identify the oxidizing agent and the reducing agent.
Try your skills at determing the oxidation number of elements within molecules or polyatomic ions.
Practice: What is the oxidation number of each underlined element?
a) P4 b) BO33– c) AsO42– d) HSO4–
Just remember if you've been oxidized then you're the reducing agent and if you've been reduced then you're the oxidizing agent.
Practice: In the following reaction identify the oxidizing agent and the reducing agent:
Cr2O72- + 6 Fe2+ + 14 H+ → 2 Cr3+ + 6 Fe3+ + 7 H2O
Concept #3: OXIDATION-REDUCTION (REDOX) reactions deal with the transfer of electrons from one reaction to another.
Concept #4: From our understanding of redox reactions we can draw connections to voltage, current, charge and power.