How do I get the ferrous sulphate into crystal state?

Question

I put steel wool into sulfuric acid. After reaction I should have ferrous sulphate. How do I get the ferrrous sulphate into crystal form?

Answer 1

Evaporate the solvent, ferrous sulfate is soluble in water

Answer 2

First of all put the steel wool in the acid and react until no more steel dissolves.  That way there's no acid left over.  The liquid should be green and non-acidic.  Test with an indicator or, if you're brave, by taste.  Then you've got an aqueous solution of FeSO4.  Evaporate the water and you'll be left with green crystals of FeSO4.  If you go on heating it you'll drive off the water of crystallisation and the green crystals will turn into a white powder; anhydrous FeSO4.