This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Both metal and copper oxidize when exposed to oxygen and this is a natural process. Copper that is exposed to the outside environment is more likely to turn green and that is why copper vases and decorative pieces in gardens are often green.
Formation of Silver Crystals: When a copper wire is placed in a solution of AgNO3, the Cu reduces Ag+ to metallic Ag. At the same time, Cu is oxidized to Cu2+. As the reaction progresses Ag crystals can be seen to form on the Cu wire and the solution becomes blue as a result of the formation of Cu2+ ions.