Fe+S===FeS
FeS+H2SO4(稀)=FeSO4+H2S,Fe+H2SO4===FeSO4+H2
(1)Fe----FeS----H2S
(2)Fe-----------H2,由(1)(2)得1摩尔铁对应1摩尔气体
Fe----------气体
1------:----1
x------------8.4/22.4=0.375mol
x=0.375mol
m(Fe)=0.375mol*56g/mol=21g
所以m(S)=8g,得n(S)=8g/32g/mol=0.25mol
所以n(S):n(Fe)=0.25:0.375=2:3