Ca-cah2-ca(oh)2-caco3-cao
Ca + H₂ = CaH₂ CaH₂ + 2H₂O = Ca(OH)₂ + 2H₂ Ca(OH)₂ + CO₂ = CaCO₃ + H₂O CaCO₃ = CaO + CO₂ (t)