2Cu+O2=2CuO
CuO+2HCl=CuCl2+H2O
CuCl2+2NaOH=Cu(OH)2+2NaCl
Cu(OH)2=CuO+H2O
2CuO=2Cu+O2
Cu+Ag2SO4=CuSO4+2Ag
CuSO4+2NaOH=Cu(OH)2+Na2SO4