(1)Ca(OH) 2+H 2SO 4==CaSO 4+2H 2O或Ba(OH) 2+H 2SO 4==BaSO 4↓+2H 2O
(2)(NH 4) 2CO 3或NH 4HCO 3(3)Ca(OH) 2和Na 2CO 3(答案和理即可)