B3
Gọi công thức FexOy:a
=>nH2= nO(FexOy)= ay= 0.15(mol)
=> a= 0.15/y
=> mFexOy= (56x + 16y). 0.15/y= 8
=> x/y=2/3 => Fe2O3
b4
nCaCO3= 0.07(mol)
=> nCO2= 0.07 => nO(FexOy)= 0.07
nFexOy= 0.07/y
=> mFexOy= (56x + 16y). 0.07/y = 4.06
=> x/y= 3/4 => Fe3O4
b5 gọi M2On:a(mol)
M2On + nH2SO4 ---> M2(SO4)n + nH2O
=> nH2SO4= an(mol)
=> mH2SO4= 98an(g)
=>mddH2SO4=490an(g)
=> mddsau= 490an + 2aM + 16an = 2aM + 506an(g)
=> mM2(SO4)n = 2aM + 96an
C%= 22.6%
=> (2aM + 96an)/(2aM +506an)= 0.226
=> (2M + 96n)/(2M+506n)=0.226
=> M= 9n
Xét n=1 => M= 9
n=2 => M=18
n=3 => M=27(Al)
=> Al2O3