Oxidation Numbers
Rules for assigning OXIDATION NUMBERS to elements:
1.	The oxidation number of an uncombined element is zero
2.	The oxidation number of a monoatomic ion is equal to the charge on the ion
3.	The oxidation number of hydrogen is generally +1, except when it is in a metal hydride when it is -1.
4.	The oxidation number of oxygen is generally -2, except when it is in peroxide (when it is -1) or when it is bonded to fluorine (when it is (+2).
5.	The sum of the oxidation numbers of a neutral compound is zero.
6.	The sum of the oxidation numbers of a polyatomic ion is equal to the charge on that ion.
7.	The oxidation number for group 1 elements is always +1.
8.	The oxidation number for group 2 elements is always +2.

Balance the following equations using the Oxidation Number Method:
1.	8 I- (aq)  +   SO42- (aq)   + 10 H+ (aq) →    H2S (aq)  +    4 I2 (aq) + 4 H2O

2.	S (s)   +  6 NO3-  (aq)  4 H+ (aq) → 6 NO2 (g)  +   SO42- (aq) + 2 H2O (l)

3.	C (s)   +   4 NO3- (aq) + 4 H+ (aq) →  4 NO2 (g)   +   CO2 (g) + 2 H2O (l)

4.	Sn (s)  +   4 NO3- (aq) + 2 H+ (aq) →  4 NO2 (g)   +   SnO32- (aq)  + H2O (l)

5.	4 Fe2+ (aq) +   O2  (g)  2 H+ (aq) →  4 Fe3+ (aq)  +  2 OH-  (aq)

6.	5 SO32- (aq)  + 2 MnO4-  (aq) + 6 H+ (aq) →  5 SO42- (aq)  + 2 Mn2+ (aq) + 3 H2O (l) 

7.	2 NO3-  (aq) +  3 S2- (aq) + 8 H+ (aq)  →  2 NO (g)  +  3 S (s) + 4 H2O (l)

8.	3 Fe2+ (aq)  +   NO3- (aq)  + 4 H+ (aq) → 3 Fe3+ (aq)  +   NO (g)  + 2 H2O (l)

9.	2 CrO4- (aq)  +  3 S2- (aq)  + 16 H+ (aq) → 2 Cr3+ (aq)  +  3 S (s) + 8 H2O (l)

10.	Cr2O72- (aq)  +   3 Sn2+ (aq) + 14 H+ (aq)  →  2 Cr3+ (aq)   + 3 Sn4+ (aq)  + 7 H2O (l)