Leprechaun Lincolns – Science Cents! Part 1 (3/1/17)
- Table Salt
- Distilled White Vinegar
- Clean bowl
- Measuring Cups and Measuring Spoons
- Shallow tray with a lid or cover (we used Petri Dishes from the lab, but any leftover food containers will work just as well)
- Pencil, Pen, or Marker
- Sheet of White Paper
- Several Paper Towels
- Pennies (we used several older Pennies as well as some newer Pennies to see if they would react differently)
Step 1 – Turning Pennies Squeaky Clean Copper
- First, we need to thoroughly clean our Pennies. One easy way to do this is to use a mixture of Table Salt and Vinegar to remove the dirty, discolored layer of oxidation from the coins. In a clean bowl, mix ¼ Cup of Distilled White Vinegar with 1 Tablespoon of Table Salt. Stir this mixture until all (or at least most) of the Salt is dissolved.
- Add the Pennies to the mixture (either add them all at once, or try slowly lowering individual Pennies into the mixture to observe any immediate color changes).
- After sitting for 15-30 seconds in the cleaning mixture, remove the Pennies to a dry Paper Towel. If there are any remaining dirty spots on your Pennies, scrub them with another Paper Towel that has been soaked in Vinegar.
- Repeat step 3 as many times as needed until you have Squeaky Clean Copper Pennies!
Step 2 – Turning Pennies “Four-Leaf Clover Green“
- With a pencil, pen, or marker, divide a blank sheet of paper into two halves. Label one half of the paper “Rinsed” and the other half “Not Rinsed”. This will be your Experiment Observation Sheet.
- Take ½ of your Squeaky Clean Copper Pennies, and rinse them with clean water. Dry them with a clean Paper Towel.
- Line the bottom of 2 lidded containers with clean, dry Paper Towels that have been folded to fit.
- To one container, add 1-2 Tablespoons of Water. Place the Clean Copper Pennies that were rinsed with water onto this Paper Towel, and place the lid onto the container. Set this container on the “Rinsed” spot of your Experiment Observation Sheet.
- To the other container, add 1-2 Tablespoons of your Vinegar-Salt cleaning solution. Place the remaining Clean Copper Pennies (the ones that have NOT been rinsed) onto the Vinegar-soaked towel.
- Sprinkle a small amount of Table Salt over the un-rinsed Pennies before covering them with the container lid. Place this container in the “Not Rinsed” spot of your Experiment Observation Sheet.
- Place your Experiment Observation Sheet in a safe and undisturbed spot. Check the two containers of Pennies after 15 minutes. After 30 minutes. After 1 hour, 2 hours, etc, and then again the next day. Record any changes that you observe in each container.
- Did you notice a color change in any of the Pennies in your containers? Were there some Pennies that didn’t change color? If you did not see ANY color changes in either container, then repeat this experiment using only older Pennies (particularly choosing Pennies that were made before the year 1982).
HOW DOES IT WORK:
We are witnessing a chemical reaction (or a combination of two substances that creates something new) between Copper Metal and Oxygen in the air. This chemical reaction, known as oxidation, happens naturally. The Vinegar and Salt helps to greatly speed up this reaction, which can take several years to happen naturally. The blue-green colored substance that appears on the Pennies is called Malachite.
While all Pennies are made of a combination of Copper and Zinc, Pennies that were made before 1982 are made of a copper-heavy mixture with 95% Copper metal and 5% Zinc metal. Newer Pennies have as little as 2.5% Copper and 97.5% Zinc, which makes them almost entirely non-reactive in this experiment!
THE MORE YOU KNOW:
Outdoor Copper structures (including Copper roof tops, hand rails, statues, and more) can naturally develop a thin coating of blue-green Malachite over time. When it occurs on its own, this layer of Malachite is called a patina.
One of the most famous instances of a patina-coated Copper figure is the Statue of Liberty, which stands in the New York Harbor of New York City. The Statue of Liberty—which was officially unveiled in 1886—was originally a bright reddish-brown copper color. Only 20 years after construction, the entire surface of the Statue of Liberty had reacted with oxygen in the air to develop the blue-green patina that still covers this 151-foot-tall statue today!
Penny Alchemy – Science Cents! Part 2 (3/1/17)
- Squeaky Clean Copper Pennies dated 1982 or earlier (see Step 1 of “Leprechaun Lincolns” for complete instructions)
- Sample of Zinc metal*
- Glass Container (a drinking glass, scientific beaker, or even a small canning jar would work well)
- Distilled White Vinegar
- Battery (we used a 1.5 Volt D cell battery, but a AA battery works just fine—it just takes a bit longer to work!)
- 2 Copper Electrical Wires (wires with Alligator Clip Ends are ideal, but are not required)
- Electrical Tape
- Plastic Spoon or Popsicle Stick
- Paper Towels
- Heat Source (Candle, Hot Plate, or Butane Torch)
- Heat-safe metal pincers or tongs
- Safety Goggles
- Adult Assistant
*Zinc can be found in many Hardware stores. It is sometimes used to make Nails, Screws, Piping, or Plating. Check the package to see if an item is made of Zinc or not. Remember, you only need a small piece of Zinc to perform this experiment.
Step 1 – Turning Pennies Super Shiny Silver
- Fill your Glass Container ½ full of clean Water at room temperature. Add Distilled White Vinegar until the glass is about ¾ full. Set this Glass in a safe spot.
- Tape one end of each Electrical Wire directly to your live Battery using Electrical Tape. Be sure to keep the other ends of the Wires from touching! If the Wires do come in contact, they might cause an electrical spark, which could give you a small burn!!!
- To the open end of the Wire attached to the Positive (+) Terminal of your Battery, attach your sample of Zinc metal using Electrical Tape or Alligator Clip.
- To the open end of the Wire attached to the Negative (-) Terminal of your Battery, attach your Squeaky Clean Copper Penny. Refer to the left-side illustration below for a diagram of this setup.
- Carefully lower the Zinc wire and the Copper wire ends into the Water-Vinegar solution. The two objects should remain close to each other within the Glass, but should not actually be touching each other. Do you see any immediate change?
- With a plastic spoon or wooden Popsicle stick, give the solution a gentle stir every 2 minutes or so. Watch closely for any changes!
- After 10-20 minutes, rotate the Penny wire so that the opposite side of the coin now faces the Zinc metal. Let the metals sit inside of the Glass for another 10-20 minutes, stirring occasionally.
- Once the Penny has completely turned a dark gray color, remove it from the wire and wash it with clean water and paper towels until it is a Super Shiny Silver. Because the silver-colored layer is so thin and delicate, it is advised to NOT use your Vinegar-Salt solution…use plain water to clean these Silver Cents.
HOW DOES IT WORK?:
This is an exciting example of the method of Electroplating (or the use of electricity to transfer metal from a charged object to cover the surface of another charged object.) Because you have attached the Penny to the negative end of the battery, or cathode, it quickly builds up a negative electric charge. The Zinc is attached to the positive end of the battery, or anode, so it will gain a positive electric charge. Just like the opposite ends of two magnets, the negative charges in the Penny will attract the positively charged Zinc particles toward it. These charged Zinc particles, which are called ions, will float through the Vinegar-Water mixture, or electrolyte, and attach to the surface of the Penny. Over time, these Zinc ions will eventually build a full coating of Zinc metal on top of the Copper Penny!
Step 2 – Turning Pennies Glittering Gold
- We’ve finally made it! This is the final Step to making out own Golden Pennies!
- Grab your Super Shiny Silver Penny (or Pennies if you’ve made a lot of them) and fill a Glass with cool water. Get an Adult Assistant to help with this last step, and be sure that everyone wears a pair of Safety Goggles!
- Ask your Adult Assistant to use a pair of heat-resistant Tongs to place your Silver Penny over the Heat Source (Butane Torch**, open Candle flame**, or clean surface of a Hot Plate).
**If you are using a Candle or a Torch, the Penny may turn a sooty black before this change actually occurs. Continue heating the Penny for 15-30 seconds after this blackening occurs to ensure that the desired chemical reaction has taken place.
- Carefully transfer the hot penny to the Glass of cool water using the heat-resistant Tongs. Be very careful, because the Penny is EXTREMELY hot! Allow the coin to return to a normal temperature before removing it from the water bath (about 30 seconds).
- Go ahead and clean your Glittering Gold Coin using the same Vinegar-Water solution from our very first experiment until it truly shines like a Gilded, Glittering, Glamorous Gold Coin!
HOW DOES IT WORK?
An alloy is a combination of metals, or a combination of a metal with another element. In the case of our ‘Gold’ Penny, Zinc atoms in the Electroplated coating have combined with the Copper atoms underneath to create a yellowish alloy called Brass.
Brass has been produced for thousands of years for its unique properties of durability and bright yellow, gold-like appearance. While it is very shiny and golden colored, unfortunately it is not real GOLD.
THE MORE YOU KNOW:
Alchemy is an ancient philosophical tradition in which alchemists worked to purify objects, especially metals, into their perfect form. One of the most extraordinary desires of European Alchemists was to discover or to create a Philosopher’s Stone—a legendary substance that could transform anything into pure gold!
Sir Isaac Newton (the famous scientist who first described the Law of Gravity) was interested in Alchemy, and he even wrote about his own private experiments and discoveries using Alchemical practices. Sadly, nobody (not even Newton) has discovered or created a Philosopher’s Stone, but many of the discoveries and practices of Alchemists have helped to form and create the Science of Chemistry!