Na2S
2Na+H2S--->Na2S+H2
2NaOH+H2S--->Na2S+2H2O
Na2O+H2S--->Na2S+H2O
2Na+S--->Na2S
3Na2CO3+Al2S3--->Al2(CO3)3↓+3Na2S
Ca3(PO4)2
3Ca(OH)2+2H3PO4--->Ca3(PO4)2+6H2O
3Ca+2H3PO4--->Ca3(PO4)2+3H2
3CaO+2H3PO4--->Ca3(PO4)2+3H2O
6CaO+P4O10--->2Ca3(PO4)2
6Ca(OH)2+P4O10--->2Ca3(PO4)2+6H2O
Mg(NO3)2
Mg(OH)2+2HNO3--->Mg(NO3)2+2H2O
Mg+2HNO3--->Mg(NO3)2+H2
MgO+2HNO3--->Mg(NO3)2+H2O
MgO+N2O5--->Mg(NO3)2
Mg(OH)2+N2O5--->Mg(NO3)2+H2O