DrRoyal Pains

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Jul 29, 2010
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PbO2 → PbSO4 : lead goes from +4 → +2 therefore PbO2 is reduced and is the cathode (choice A is correct)
Pb → PbSO4 : lead goes from zero → +2 therefore Pb(s) is oxidized and is the anode

For the first reaction I understand how lead is +4, but I do not understand how it is +2 in product. I know oxygen will be -8, but for some reason I am stumped on the Pb and S in PbSO4. What am I missing?
 

LetsGo2DSchool

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You can approach it in two ways. The easier way is to look at SO4 as one entity which is equal to -2. Thus Pb has to be +2.

The other way is more difficult: O4 is -8 so then S must be ? which makes Pb equal ?

Whenever you see NO3, SO4, PO4, etc, do it the easier way.
 
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