Oxidized Copper
Figure 1. Oxidized copper (patina) on a building. (Source: "Beacon Hill copper patina facade" by gregraisman) The basic reaction of copper and atmospheric oxygen, which converts copper to copper oxide, is: 2 Cu(s) + O 2 (g) –> 2 CuO(s) The copper to patina conversion is a multiple-step process, and it takes a long time to form …