CaO + H₂O = Ca(OH)₂ CaO + CO₂ = CaCO₃ 2HCl + Be(OH)₂ = BeCl₂ + 2H₂O Be(OH)₂ + CO₂ + 3H₂O = [BeCO₃·4H₂O] H₂O + CO₂ = H₂CO₃