1) PTHH: Fe +2 HCl -> FeCl2 + H2
-> Khí đó là khí H2 (hidro)
nFe= 2,8/56=0,05(mol) -> nH2=nFe=0,05(mol); nHCl= 0,05.2=0,1(mol)
V(H2,đktc)=0,05.22,4=1,12(l) ; mHCl=0,1.36,5=3,65(g)
2) nCaO=42/56=0,75(mol)
PTHH: CaCO3 -to-> CaO + H2O
nCaCO3=nCaO=0,75(mol) => mCaCO3= 0,75.100=75(g)