Polyatomic ions

[golgiapparatus88]

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Hey guys, I'm kind of confused on how you determine the products of reacting who polyatomic ions.

To give a simple example (which I understand), Pb(NO3)2 + Na2SO4 yields PbSO4 and 2NaNO3.

To give an example which I'm confused on and don't know how to finish, PbSO4 + KI yields PbI2 and 2KSO4?

I guess I'm just unsure of how you determine subscript or coefficient. Thanks

 

[Rabolisk]

It would be PbI2 and K2SO4. Polyatomic ions are just ions with multiple elements. You treat SO4 as any other anion with a charge of -2. That means that there has to be twice as many K+ to balance out the charge. You use coefficients to balance equations and subscripts to balance charge in salt formation from ions.

 

[sanode]

This chart of charges & common ions may help. Once you know the charge of say SO4 is -2, so XS04 = charge 0 (where X is any element total charge +2

http://www2.pvc.maricopa.edu/tutor/chem/chem130/nomenclature/polyatomicion.html