a. Na → Na2O → NaOH → Na2CO3→ NaCl → NaOH
2Na + 1/2O2 --t0--> Na2O
Na2O + H2O -> 2NaOH
2NaOH + CO2 -> Na2CO3 + H2O
Na2CO3 + 2HCl -> 2NaCl + CO2 + H2O
2NaCl + 2H2O --điện phân nóng chảy--> Cl2\(\uparrow\) + H2\(\uparrow\) + 2NaOH
b. Ba → BaO → Ba(OH)2 → BaCO3 → BaCl2
2Ba + O2 -> 2BaO
BaO + H2O -> Ba(OH)2
Ba(OH)2 + Na2CO3 -> BaCO3 + 2NaOH
Ba(HCO3)2 +CaCl2 -> BaCl2 + CaCO3 + H2O + CO2