Those tart little lemons work to remove copper oxide because they contain citric acid. Since lemon juice has the highest concentration of citric acid of any fruit, it works the best. Other juices that rank highly include lime, grapefruit, and orange juice.

What You’ll Do

1. Guess which liquid will make a penny shine.
2. Set one penny aside.
3. In one cup, pour enough vinegar to cover the penny.
4. In the other cup, pour enough liquid soap to cover the penny.
5. Wait at least ten minutes.
6. Remove the pennies, rinse them in water, and rub them with a paper towel.
7. Compare all three pennies.

If you choose to clean a penny with a heated liquid, the penny may consequently be cleaner or less clean than if you chose to use the liquid at room temperature. The temperature is the independent variable, the consequent cleanliness is the dependent variable.

The “dirt” on the pennies was a new chemical substance called copper oxide. It doesn’t easily come off, as you found out by trying to scrub them with plain water. When you mix the salt and vinegar, however, this makes a new substance, too; a type of acid. This acid is really good at breaking down the dirty pennies.

Copper oxide dissolves in a mixture of weak acid and table salt-and vinegar is an acid. You could also clean your pennies with salt and lemon juice or orange juice, because those juices are acids, too.

That’s because cola has acid in it – phosphoric acid, to be precise. When the copper oxide (the pennies) and the phosphoric acid (the cola) get together in the bath, the acid reacts with the copper oxide on the pennies and dissolves it. That’s why the pennies get shiny.

The active ingredient in Coke is phosphoric acid. Its pH is 2.8. It will dissolve a nail in about 4 days.

Simply place one coin in a glass or tub and pour coke over the top, enough so that it is fully submerged in the liquid. Leave the coin to soak for about 5 minutes or so and then check on its condition. If you feel that it needs longer, you can soak it for up to 15 minutes.

25 Most Valuable US Pennies

• 1.) 1944 Steel Wheat Penny – Worth $110,334.
• 2.) 1943 Copper Wheat Penny – Worth $85,782.
• 3.) 1856 Flying Eagle Penny – Worth $25,000.
• 4.) 1873 Indian Head Penny – Worth $10,000.
• 5.) 1858 Flying Eagle Penny – Worth $10,000.
• 6.) 1857 Flying Eagle Penny – Worth $7,000.
• 7.)
• 8.)

CoinTrackers.com has estimated the 1946 Wheat Penny value at an average of 15 cents, one in certified mint state (MS+) could be worth $4.

The combination of vinegar (a weak solution of acetic acid), and table salt (sodium chloride) helps to dissolve the copper oxide, and also forms the blue copper(II) ion, which is soluble in water. The penny becomes shiny again!

Leave the pennies for around five minutes in the glass of vinegar or lemon juice. If they’re extra dirty or if you’re cleaning a lot simultaneously, give them a few more minutes for good measure.

If your soap-washed, vinegar-soaked pennies still need more cleaning, scrub them with baking soda. As a gentle abrasive, baking soda is great for getting into the tiny nooks and crannies of coins to polish away the last traces of dirt and tarnish.

Hydrogen peroxide is the perfect, all natural solution to clean coins with. Its as simple as dropping the coins in the hydrogen peroxide solution and then waiting for 1-2 days. Before you start, get rid of any excess dirt and debris where applicable. Instead, rinse the coins using running water.

Baking soda will bring back the shine to most coins. Baking soda is used for many things, including cleaning costume jewelry. Due to its mild abrasiveness, it removes stuck-on particles and will polish most hard substances, including coins.