Taco Sauce Penny Cleaner It's one of those things you hear about but wonder if it's true. email to friend
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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 pennies. Remember to wash your hands... and don't lick your fingers (pennies are really dirty and some taco sauces are really spicy!).
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 of the pennies that touched the taco sauce and the bottom side. It's no myth... taco sauce does the trick.

So, which ingredients are responsible for the cleaning power of taco sauce? Let's find out...

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 (vinegar, tomato paste, salt, and water).
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. Which ingredient cleaned the pennies the best?

 

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 Paste + 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 nor 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.