Ca -> CaO -> CaCl -> Ca(OH)2 -> CaCo3
1)2Ca+O2=2CaO
2)CaO+2HCl=CaCl2+H2O
3)CaCl2+2NaOH=2NaCl+Ca(OH)2↓
4)Ca(OH)2+K2CO3=2KOH+CaCO3
2Ca +O2=2CaO
CaO+HCl=CaO=H2O