M=Cu,Ag,Au 4M+,+2H,O+8CN>4[M(CN)+40H 4Cu+0,+2H,O+8NH3> 4[CuNH3)2](无色)+4OH 02 [CuNH,)4]2+(蓝) Aqueous ammonia can't be shipped in copper containers. 2Ag+2H2S+02->2Ag2S+2H2O 银器年久变黑。M  C u, Ag, A u [Cu(N H ) ] ( ) 2 3 4  蓝 Aqueous ammonia can’t be shipped in copper containers. 2Ag  2 H 2 S  O 2  2Ag 2 S  2 H 2 O O2 银器年久变黑.        4[Cu(NH ) ] ( ) 4OH 4Cu O 2H O 8NH 3 2 2 2 3 无色    4MO2  2H2 O8CN 4[M(CN)2 ]  4OH