KOH + H3PO4 ->
Ca(OH)2 + H2SO4 ->
Ba(OH) + HNO3 ->
Fe(OH)2 + H2S ->
Fe(OH)3 + H2S ->

1 K3PO4+H2O

2 CaSO4+H2O

3 Ba(NO3)2+H2O

4 FeS2+H2O

5 FeS3+H2O

3KOH+H₃PO₄=K₃PO₄+3H₂O

Ca(OH)₂+H₂SO₄=CaSO₄+2H₂O

Ba(OH)₂+2HNO₃=Ba(NO₃)₂+2H₂O

Fe(OH)₂+H₂S=FeS↓+2H₂O

2Fe(OH)₃+3H₂S=Fe₂S₃+6H₂O