Oxidation Rules Review:
1. The oxidation number of an atom in an elemental substance is zero.
2. The oxidation number of a monatomic ion is equal to the ion's charge.
3. Oxidation numbers for common nonmetals are usually assigned as follows:
• Hydrogen: +1 when combined with nonmetals, -1 when combined with metals
• Oxygen: -2 in most compounds, sometimes -1 (so-called peroxides, 0,2^2-), very rarely - 1/2 (so-called
superoxides, 02^-), positive values when combined with F (values vary)
• Halogens: -1 for F always, -1 for other halogens except when combined with oxygen or other halogens (positive oxidation numbers in these cases, varying values)
4. The sum of oxidation numbers for all atoms in a molecule or polyatomic ion equals the charge on the molecule or ion.
Fill out these please:
Assign oxidation numbers to each element. Write correct half reactions for each. Balance these half reactions for extra credit!
Reaction 1: Fe^2+ + MnO4 ——> Fe^3+ + Mn^2+
Reaction 2: Sn^2+ + lO3 ——-> Sn^4+ + l
Reaction 3: Mn^2+ + BiO3^- ——> Bi^2+ + MnO4
Reaction 1:
Fe^2+ --> oxidation number of Fe = +2
MnO4 --> oxidation number of Mn = +7, oxidation number of O = -2
Half reaction 1:
Fe^2+ --> Fe^3+
Oxidation: Fe^2+ --> Fe^3+
Reduction: MnO4 --> Mn^2+
Reaction 2:
Sn^2+ --> oxidation number of Sn = +2
IO3 --> oxidation number of I = +5, oxidation number of O = -2
Half reaction 2:
Sn^2+ --> Sn^4+
Oxidation: Sn^2+ --> Sn^4+
Reduction: IO3 --> I^-
Reaction 3:
Mn^2+ --> oxidation number of Mn = +2
BiO3^- --> oxidation number of Bi = +5, oxidation number of O = -2
Half reaction 3:
Mn^2+ --> MnO4^-
Oxidation: Mn^2+ --> MnO4^-
Reduction: BiO3^- --> Bi^2-