Which Cleaning Solution is Best For Cleaning Coins?

Problem: My problem was I needed to figure out what solution was the best for cleaning pennies.

Hypothesis: My hypothesis was that the lemon juice would be the best cleaning solution because it's used for preserving apples, so it will probably be good for cleaning coins.

Procedure: Get materials

Mix solutions

Put one tarnished penny in each solution

Wait afternight

Using latex gloves, take each penny out and examine

Take picture

Clean each penny with toothbrush

Examine and take picture

Record data and observations

Conclusion: In conclusion, I found out that the lemon juice was the best cleaning solution for the pennies. My hypothesis was correct because I predicted that the lemon juice would clean the best and it did, therefore, I was correct.

Abstract: Which Solution is the Best for Cleaning Coins?

For my science fair project, I chose to clean pennies. I chose to do this project because I was interested in the efficientiency of cleaning solutions. I would find coins on the street or around my house and they would be extremely dirty. I always wondered how I could clean them effectively so I could get a clean coin. I never wanted to pick up money off the ground because it was dirty and germy, but (because I found a way to clean them well), I am able to have clean coins. My hypothesis is the lemon juice would clean the best because it’s acidity will help the coin break down the debris and it’s used to preserve apples from spoiling so it probably prevents bacteria from growing on substances.

I started my experiment by getting my materials. I needed plastic spoons, latex gloves, toothbrushes, and plastic cups along with my six (including my control variable) cleaning solutions. For my cleaning solutions, I used a ½ teaspoon of baking soda mixed with water, lemon juice, soda, dish soap, bleach, and water (control). I filled each cup up to the 1st line. I set up my experiment on a table and mixed each solution together. I dropped a penny in each cup and let it sit for a day. After waiting overnight, I took each penny out (using latex gloves and plastic spoons) and examined them before going in with the toothbrushes. I took some pictures of the before and after images. Then, I went in with the toothbrush, examined each of them, and recorded my results.

My observations concluded that the lemon juice was the best cleaning solution for cleaning coins. I based each solution on a scale of 1-5 (1 being the worst and 5 the best). I ended up with results showing that the baking soda solution scored a 3, the dish soap with a 3, the soda with a 4, the bleach with a 1, water with a 2, and lemon juice with a 5. The bleach was the worst solution because, when I was looking at the penny, I noticed a weird white substance (one like the green substance that grew on the coin) growing on the surface of the coin.

My experiment was accurate because I measured each solution carefully and filled each cup to the same amount. I used really dirty pennies for each solution and waited for a good amount of time before examining. I learned that lemon juice works very well with cleaning coins and bleach does not. I could improve this experiment by using more than one penny in each solution, testing each solution more than once, and maybe if I tested another solution it would’ve been more accurate. My hypothesis was correct because I predicted the lemon juice would be the best and I was right. In conclusion, I found out that the lemon juice was the best cleaning solution for cleaning coins.

Data: