Elemental iron in ferrous sulfate

[barryj]

I have read that ferrous sulfate has 65mg of elemental iron per 325 mg tablet. Then I read that dried ferrous sulfate has 50 mg per 160 mg tablet. Does this mean that the wet ferrous sulfate has water with it? It seems that the dried version matches the percentages based on the chemical formula.

 

[Merlin3189]

I think the common form of Ferrous Sulphate is the heptahydrate with a molecular weight of about 276, containing 20% Fe
The anhydrous form would have a molecular weight of about 150 and contain 37% Fe. (Which would suggest the tablet is not all anhydrous ferrous sulphate.)

 

[barryj]

This makes sense. Thanks

 

[Merlin3189]

Oh - just noticed, I can't add up! The MW for anhydrous ferrous sulphate is nearer 152 and the heptahydrate 278, but it's near enough to keep the rounded %s the same.

 

[barryj]

I noticed that. I figured we were using a different version of the periodic table :-)