Fe+H2SO4→FeSO4+H2↑
n(Fe)=50×70%/56=0.625mol
n(H2SO4)=70×50%/98=0.357mol
所以铁过量
S守恒,有H2SO4→FeSO4→FeSO4·7H2O
m(FeSO4·7H2O)=0.357×278=99.29g