Tuesday, September 28, 2010

The Statue of Liberty, Stoichiometry and introductory chemistry.....

(Photo taken from the Introduction to Chemistry text by Bauer, 2010)

What does the statue of liberty in New York have to do with introductory chemistry? Actually, a lot. On the most basic level, the reason it was renovated in the 80s is very related to introductory chemistry. If we want to present the reactions of the statue of liberty accurately then we must consider stoichiometry and balanced equations.

The statue had copper panels on the outside and iron used in the inner framework. Over time, the copper oxidized in air to form copper (II) hydroxide, copper (II) carbonate, and copper (II) oxide while the iron formed iron (III) oxide. This created a displacement reaction situation. Copper metal was in contact with iron (III) ions and iron in contact with copper (II) ions.  Here is where the problem got really messy:

Fe (s)  +   CuO(s)   gives  Cu(s)  +   FeO(s)  (oh how I wish I could figure out subscripts and arrows in blogger.com)
According to the metal activity chart is Fe more active than copper? Yes, therefore it will displace copper's position within the copper (II) oxide compound and create an iron oxide.

This displacemnet further exacerbated the oxidation problem. In fact it accelerated the problem by a factor of 1000 and the statue needed to be rebuilt.

See page 179 of your text for more information.