[alwaysanewb]

This problem is kinda confusing but here it goes.
Pregnant women take 325 mg tablets of FeSO₄ as a supplement. The Fe ion present in those pills is poisonous to small children.  The ingestion of 550mg of Fe ion will kill a 22lb child.  What is the minimum number of whole tablets a 22lb child needs to ingest to become fatally poisoned?

Here is a little bit of work I put out:
Molecular Weight of Fe = 55.8
Molecular Weight of S =  32
Molecular Weight of 0₄ = 64
Molecular Weight of FeSO₄ = 151.8

Now,I'm looking for chemical composition of Fe
chemical comp of Fe = (mass of Fe/mass FeSO₄) x 100
                            = 36.7%

Now, I set up an equation like this to solve for x (the chemical composition in mass for Fe):
(36.7g/100) * (x/325mg)                  * means to multiply

But then I realized that I have to convert the 36.7 to miligrams and I get this equation:
100000x = (36700)(325)
So x = 119.2mg and we need 550 mg of Fe ion. So 550/119.2 = 4.61 rounded up = 5 tablets of FeSO₄
So i hope i right bc this problem was a time consuming.

[Borek]

So 550/119.2 = 4.61 rounded up = 5 tablets of FeSO₄

Looks OK to me.