Chemistry Reference
In-Depth Information
Example 1 results summary:
2Na + Cl
2
2NaCl
A.
The oxidation numbers for each substance involved:
2Na
0
+ Cl
2
0
2Na
1+
Cl
1-
B.
The substance being oxidized:
sodium (Na)
C.
The oxidizing agent:
chlorine (Cl
2
)
D.
The substance being reduced:
chlorine (Cl
2
)
E.
The reducing agent:
sodium (Na)
Notice that the oxidizing agent is also the substance that is reduced,
and the reducing agent is also the substance that is being oxidized. Also,
notice that the element oxygen didn't even appear in this redox reaction,
so make sure that you understand the modern definition of oxidation.
Let's try a somewhat more complicated example next.
Example 2
For the following redox reaction, identify:
A. The oxidation numbers for each substance involved.
B. The substance being oxidized.
C. The oxidizing agent.
D. The substance being reduced.
E. The reducing agent.
SnCl
2
+ 2FeCl
3
2FeCl
2
+ SnCl
4
A.
We can start assigning oxidation numbers based on Rule #5, which
tells us that chlorine, being a halogen that is acting as a negative ion in
a compound, must show an oxidation number of -1 in all four com-
pounds, as shown here:
SnCl
2
1-
+ 2FeCl
3
1-
2FeCl
2
1-
+ SnCl
4
1-
Remember: Each atom of chloride has a -1 charge. To get the total
negative charge on each compound, we must multiply by the subscripts
for the chloride ion. The first compound (SnCl
2
1-
), for example, will have
