Taco Sauce Penny Cleaner
It's one of those things you hear about but wonder if it's true. Can you
use taco sauce to clean the tarnish off of a penny? Believe it or not,
taco sauce does a great job of cleaning pennies, but how does it
work? Which ingredients in the taco sauce really do the cleaning?
Eight year old Jack Spangler tackled these questions as part of his
science fair project and made a surprising discovery.
Materials
•Dirty Pennies - try to collect tarnished pennies that all look the same
•Taco Sauce - Mild sauce from Taco Bell was used for these tests
•Vinegar
•Tomato Paste
•Salt
•Water
•Small plates
Experiment
1.Let's start by proving that taco sauce does a good job of cleaning
pennies. Place several tarnished pennies on a plate and cover them
with taco sauce. Use your fingers to smear the taco sauce all over
the surface of the penny. Remember to wash your hands... and don't
lick your fingers (pennies are really dirty).
2.Allow the taco sauce to sit on the pennies for at least two minutes.
3.Rinse the pennies in the sink and look at the difference between
the top side that touched the taco sauce compared to the bottom
side. It's no myth... taco sauce does the trick.
Which ingredients are responsible for the cleaning power of taco
sauce?
1.Place two or three equally tarnished pennies on each of four
plates. Use masking tape or a sticky note to mark each plate with the
ingredient you are testing.
2.Cover the pennies with the various ingredients and allow them to
sit for at least two minutes.
3.Rinse the pennies from each test plate with water and write down
your observations.
Much to our surprise, none of the ingredients did a good job of
cleaning the dirty pennies. In fact, the results were terrible. Where did
we go wrong? Maybe two or more of the ingredients work together to
react against the copper oxide on the penny. This assumption
helped set up our second test using various combinations of tomato
paste, vinegar and salt.
1.Place two or three equally tarnished pennies on each of three
plates. Make three signs that say "Tomato Paste + Vinegar", "Salt +
Vinegar", and "Tomato Past + Salt".
2.Cover the pennies with each of the mixtures and give the
ingredients at least two minutes to react.
3.Rinse the pennies under water and write down your observations.
Observations
How does it work?
The clear winner is the mixture of vinegar and salt. Neither vinegar or
salt by themselves cleaned the pennies, but when they were mixed
together something happened. The chemistry behind the reaction is
somewhat complicated but very interesting. Dr. Laurence D.
Rosenhein from the Department of Chemistry at Indiana State
University published an article in the Journal of Chemical Education
in 2001 about this very reaction. According to Dr. Rosenhein, salt
(sodium chloride) plays a very important role in making a copper
chloride complex. Salt breaks down into sodium ions and chloride
ions and it is the chloride ions that form a surprising complex with
the copper ions (specifically the Cu+1). It is also well known that a
mixture of lemon juice and salt does a good job in removing tarnish
from metals and works very well on pennies. By themselves the salt
and weak acid do very little in the way of removing the coating of
copper oxide on the penny, but together these ingredients make a
great cleaning agent. Now you know the cleaning power of taco
sauce.
Additional Info
Editor's Note: A number of versions of this experiment have been
submitted to this website over the years. Recently, a reader pointed
out a great write-up found at www.cruftbox.com The author shows
similar results.
Experiment From Steve Spangler Science
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