## Chemistry: The Molecular Science (5th Edition)

We see that there is a sulfate ion ($SO_4 ^{2-}$). Here, balancing the charges is more difficult than the previous problems. Since Sulfate has three compounds with a charge of 2-, the 3 sulfate ions create a charge of 6-. Since there are 2 Cobalt atoms, and since the net charge is 0, we know that the Cobalt atoms must have a charge of 6+/2=3+. Thus, we name the compound: Cobalt III Sulfate