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Science Rocks!

Polishing Pennies


your results

Sent in by:
Adriana of AZ

Make your pennies sparkle!

Materials Needed

  • lemon juice
  • old, dull pennies
  • paper cups
  • paper towels



  1. Check with a grown-up before you begin.
  2. Put a penny in a paper cup.
  3. Pour some lemon juice into the cup. Make sure the penny is completely covered.
  4. After about 5 minutes, take the penny out of the lemon juice, rub it off with a paper towel. What does the penny look like now? It should be much brighter.
  5. A new penny is partly made from bright, shiny copper. But after a while, it loses its shine. Why? Because the copper mixes with the oxygen in the air and makes a coating called an oxide. When you put the penny in lemon juice, the acid in the lemon chemically removes the oxide, and you're left with a bright copper penny.

Now's your chance to experiment. Try out different kinds of liquids, make some predictions, compare your results and send them to ZOOM. Which liquids shined your pennies the most? The least? Do acids work better than bases? To find out which liquids are acids and which are bases, check out the grOOvy online gizmo, Kitchen Chemistry, for more scientific kitchen kOOkineSS!

Some of your Results

Elizabeth, age 7 of Latham, NY wrote:
I tested lemon juice, lemon lime soda, canola oil, baking soda and vinegar, soy sauce, and jalapeno pepper juice. The soy sauce worked well, but the jalapeno juice was the best!

Matthew, age 7 of Wylie, TX wrote:
the acid and the base made it clean off.

Alma, age 11 of Ventura, CA wrote:
it worked the penny polished amazingly. I couldnt believe it was that clean I was flabergasted!!!

Abigail, age 9 of Chicago, IL wrote:
i found out that soysauce made the penny shiny then the others I used. the others I used were olive oil vegtable oil and vinager

Asley, age 6 wrote:
when I did this experiment I found out that the lemon juice worked better than vinegar and pepsi it was pretty fun doing this project

Madeline, age 8 of Elgin, IL wrote:
Some of the pennies were still dirty and had bubbles on them.

Rebecca, age 5 of New York City, NY wrote:
I used lemon juice and it was so bright, I could hardly keep my eyes open.

Therese, age 10 of Lusby, MD wrote:
We tried white vinegar, lemon juice, orange juice, hand soap, dish soap, clear soda and water. The winner was lemon juice.

Jaden, age 9 of Lithia, FL wrote:
Using lemon juice, water, coke zero, and ginger ale, I found that because of the acid in the lemon juice, the penny appeared brighter than just scubbing with water. The c. z didn't work as well because it contained no acid and just made it sticker with all the carbonation. In last comes the g. a with a bad outcome. Because of the no acid liquid, it did not make the penny any more shiner than it already was.

Brian, age 8 of Burnaby, BC wrote:
I tried it with a weaker acid-vinagar-pH 2. 2, lemon juice pH 2(The lower to 0, the more acidic)

Noah, age 7 of Half Moon Bay, CA wrote:
lemon juice and vinegar worked the best.

Caitlin, age 12 of Philadelphia, PA wrote:
When I did it I predicted that vinegar/baking soda was going to work the best. The Result: Lime Juice worked the best. Vinegar/Baking Soda was the worst. ~sigh~

Alxia, age 9 of Brooklyn, NY wrote:
I used fresh lemons and squeezed it my self. It was fun. Seeds got in it though. BUT, IT WORCKED THATS WATS INPORTANT!!!

Evan, age 8 of Waterford, OH wrote:
i used salt and vinegar and it works good!

Marie, age 14 wrote:
I did an expierement it consisted of ketchup, mustard, salt water, and lemon juice. I found that the lemon juice worked best. It also had chemical reaction, it starts to bubble.

Jessica Ann of Glen Ellyn, IL wrote:
After trying vineger and lemon juice I tried mixing them and it worked out awsome!

Celeste, age 10 of Sun Valley wrote:
I put the penny in coke and the penny turned brighter and cleaner. It was so much fun.

Tatianna, age 11 of Raleigh, NC wrote:
It was fun. I polish every single pennies I saw.

Tony, age 6 of Easton, MA wrote:
My penny became very shiny when I put it in the lemon juice and then polished it.

Jailene, age 12 of Chicago, IL wrote:
the lemon made the britest.

Malique, age 12 of Fall River, MA wrote:
I used four new liquids: orange juice, apple juice, milk, and red gatorade. #1 was a tie between apple juice, gatorade, and orange juice.

Fianna, age 11 of OH wrote:
i tried a mix of lemen juice, vinegar and baking soda and my pennies were polished in about 10 - 15 minutes!

Cassie, age 8 of OH wrote:
when I poured the lemon juice they where clean as a cleand and polished dimend.

David, age 8 of Brooklyn, NY wrote:
When I did this experement my pennies really did shine! But I was amazed that lemen juice can shine pennies so good!

Victoria, age 10 of Gilbert, AZ wrote:
the soda and the lemon juice actually worked.

Lucy, age 9 of Duluth, MN wrote:
I did it in school and we tried it with coke and or water.

Andrew, age 11 of Los Angeles, CA wrote:
I tried it with bleach, Taco sauce, vinegar and salt, soap and water, ketchup, and cola.

Sriha, age 6 of Novato, CA wrote:
I did it with lemon juice and it worked. I did it at home and at school. I was the rock star I know how pennies get dull.

Daniel, age 12 of Ridgewood, NJ wrote:
It cleaned most of the penny but still left with a tiny bit of dirty spots but barely noticeable. This works with just about any acid.

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