Day 103

Remember the days when science was fun? When candles sucked boiled eggs into jars and food coloring turned carnations blue? Well, you can live through those days once more! Behold the penny-cleaning powers of vinegar and salt on oxidized copper!

Before:


During:


After:

(Fun fact: Note the penny on the far left, which has a small "s" beneath the date 1970. This mint mark indicates that this penny is from San Francisco, just like me.)

My college-level understanding (supplemented by Wikipedia) of what happens runs something like this: salt (NaCl) dissolves in vinegar (which is already a solution of acetic acid, CH3COOH). Both acetic acid and salt dissolve in water, creating sodium (Na+), chloride (Cl-), acetate (CH3COO-), and hydrogen (H+) ions in the solution. Dull pennies, coated with copper oxide (CuO), get thrown into the mix. Chloride ions bond to the copper to make copper chloride (CuCl2) and hydrogen ions bond to to the oxygen to make water (H2O). If we had added our pennies to a solution of hydrochloric acid (HCl), we would have had the same outcome, since hydrogen (H+) and chloride (Cl-) ions were the main actors in removing the copper oxide (CuO).

It sure is reassuring to know that my college education is arming me with the tools necessary to understand an eight year old's rainy day science project, or an entire episode of Bill Nye the Science Guy, for that matter.

Well, that sure was fun.