Notes from Janice’s Desk
Lately there have been several water leaks in my house. One was due to an old water heater that has not been used for years. I must admit that the beautifully colored crusted areas on the pipes caught my eye. If you look close you can see dark blue crystals. While I was intrigued with the colors and the chemistry behind their production, most of the excitement was dampened by the plumbers bill. But I did learn something new from him. Seems that the corrosion started because two metals were in contact with each other. I later discovered that this is called two metal corrosion or galvanic corrosion.
The term corrosion seems to be a catch all for stuff deteriorating because of chemical reactions. My water pipes were made of different kinds of metals–copper, zinc, and iron–thus all the different colors of corrosion.
Iron generally corrodes by combining with oxygen forming a reddish-brown chemical commonly called rust.
The white corrosion in the photo is zinc oxide, commonly called zinc white.
Except for water pipes, copper corrosion is expected and wanted by artists who create copper sculptures placed outdoors as well as copper used for roofs. Copper corrosion has a common name of patina.
For information about the rusting of iron, see CHEMISTRY:RUSTING
For instruction on how to write the chemical reactions for the rusting of iron, see CHEMISTRY: RUSTING Equation.