Copyright © 2008 Pearson
Prentice Hall, Inc.
Oxidation-Reduction (Redox) Reactions
Cr2O72-
-2
+1
x
4.The sum of the
oxidation numbers is 0 for a neutral compound and is equal to the net charge for a polyatomic ion.
x = +6
2(x) + 7(-2) = -2 (net
charge)
H2SO3
x
-2
x = +4
2(+1) +
x + 3(-2) = 0 (net charge)