Hi, I read about an old method of preparing iron (iii) sulfate. You would heat pyrite (FeS2) in air to get FeSO4 which could then be further oxidized,
12 FeSO4 + 3 O2 → 4 Fe2(SO4)3 + 2 Fe2O3.
My question is: will FeS form Fe2(SO4)3 if heated enough in air?
FeS + 2 O2 → FeSO4 ?