Is tarnishing considered a physical or chemical change?

1 Answer
Nov 28, 2016


#"Tarnishing"# is properly considered a chemical change.


Chemical change is characterized by the formation of new substances, and the making and breaking of chemical bonds. When a metal tarnishes, typically copper, brass, silver, aluminum, or magnesium, it reacts with atmospheric oxygen to form a thin oxide coating. When iron tarnishes, we call the phenomenon #"rusting"#. Some metals, particularly gold, are very resistant to tarnishing, and this is one of the reasons why gold is so valued as an ornamental metal.

And then you have to tell your butler to polish the silverware with some (usually abrasive) metal cleaner.