Author: P Lawson

Chemistry 30
Unit 6: Redox Reactions and Electrochemistry
Practice Set 1: Oxidation Numbers and Redox Reactions

1. Determine the oxidation number of each element in the following compounds.

Rules: | 1.	Pure elements have an oxidation number of 0
| 2.	If the compound is an ionic compound, the oxidation number for each element is the ion’s charge
| 3.	The oxidation number of hydrogen in a compound is +1

4.	The oxidation number of oxygen in most compounds is –2 
(peroxides are the exception; in peroxides oxygen has an oxidation number of –1)

| 5.	The sum of the oxidation numbers in a compound is zero.
| 6.	The sum of the oxidation numbers in a polyatomic ion is equal to the ion charge.

| | Hint | Oxidation Numbers for each Element
a. | SnCl_4 | Rule 2 | Sn | | | Cl | | | | | | |
b. | Ca_3P_2 | Rule 2 | Ca | | | P | | | | | | |
c. | SnO | Rules 4, 5 | Sn | | | O | | | | | | |
d. | Ag_2S | Rule 2 | Ag | | | S | | | | | | |
e. | HI | Rule 3, 5 | H | | | I | | | | | | |
f. | N_2H_4 | Rule 3, 5 | N | | | H | | | | | | |
g. | Al_2O_3 | Rule 4, 5 | Al | | | O | | | | | | |
h. | S_8 | Rule 1 | S | | | | | | | | | |
i. | HNO_2 | Rules 3, 4, 5 | H | | | N | | | O | | | |
j. | O_2 | Rule 1 | O | | | | | | | | | |
k. | H_3O^+ | Rules 3, 4, 6 | H | | | O | | | | | | |
l. | ClO_3^- | Rules 4, 6 | Cl | | | O | | | | | | |
m. | S_2O_3^2- | Rules 4, 6 | S | | | O | | | | | | |
n. | KMnO_4 | Rules 4, 5, 6 | K | | | Mn | | | O | | | |
o. | (NH_4)_2SO_4 | Rules 4, 5, 6 | N | | | H | | | S | | | O |

				

2.  Determine the oxidation number of carbon in each of the following compounds:

	a.  methane, CH_4					b.  formaldehyde, CH_2O		

	c.  carbon monoxide, CO				d.	carbon dioxide, CO_2

Unit 6: Redox & Electrochemistry	Practice Set 1	Page  of