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We did a little penny cleaning experiment today. We filled some cups with different things in or kitchen to see which one would get our dirty pennies the cleanest. I had my kids each take a guess at which thing would get the pennies the cleanest. They were way off, so it was fun to see which really did get them clean. We left them in for 5 minutes then wiped them clean with paper towels.
Soy sauce and lemon juice were the clear winners, with vinegar & ketchup coming in after- maybe with a little more time they would have gotten a little bit cleaner.
Pennies are made of copper. Over time the oxygen in the corodes it with a coating called oxide. The acid in lemon juice & apparently soy sauce chemically break down the oxide and leave the penny shiny.
I remember one time doing this with a packet of hot sauce from Taco Bell- I know random- I was in high school. My friends & I thought it was so cool that the penny got so shiny. I didn’t have any hot sauce on hand, but you could try that one out if you have it…