61.
P2O5+3H2O-->2H3PO4
H3PO4+3KOH-->K3PO4+3H2O
2K3PO4+Ca(OH)2-->Ca3(PO4)2+6KOH
2KOH+H2S-->K2S+2H2O
K2S+2HCL-->H2S+2KCL
62.
2H2S+3O2-->2H2O+2SO2
2SO2+O2-->2SO3
SO3+H2O-->H2SO4
H2SO4+Cu(OH)2-->CuSO4+2H2O
CuSO4+Na2S-->CuS+Na2SO4
63.
CuO+H2O-->Cu(OH)2
Cu(OH)2-->Cu+2H2O
Cu+S--> CuS
2CuS-t->Cu2S+S
Cu2S-->CuS+Cu