Bài 2
MnO2+4HCl->MnCl2+Cl2+2H2O
Cl2+H2->2HCl
NaOH+HCl->NaCl+H2O
2NaCl+2H2O->2NaOH+Cl2+H2
FeCl3+3NaOH->Fe(OH)3+3NaCl
2Fe(OH)3->Fe2O3+3H2O
Fe2O3+3CO->2Fe+3CO2
CO2+Ca(OH)2->CaCO3+H2O
Bài 3
CaCO3+2HCl->CaCl2+CO2+H2O
nCO2=0,448/22,4=0,02 mol
=>nCaCO3=0,02 mol
%mCaCO3=0,02x100/5x100=40%
%mCaSO4=100-40=60%