So you've got positively charged iron ions floating in your vinegar with the positively charged copper ions. Originally, the steel nail was neutrally charged-but when the iron ions left their electrons behind, the nail then became neg-atively charged. And remember what we said way back at the beginning of this section: negative charges attract positive charges.
The negative charges on the nail attract positive charges in the liquid. Both the iron ions and the copper ions are positively charged. The copper ions are more strongly attracted to the negative charge than the iron ions, so they stick to the negatively charged nail, forming a coating of copper on the steel. Each water molecule is made up of two hydrogen atoms and an oxygen atom. In an acid like vinegar or lemon juice , lots of hydrogen ions hydrogen atoms that are missing an electron are floating around.
In the chemical reactions at the surface of the screw, some of these hydrogen ions join and form hydrogen gas. The bubbles that you see coming off the screw are made of hydrogen gas.
This and dozens of other cool activities are included in the Exploratorium's Science Explorer books, available for purchase from our online store. Lean another nail against the side of the bowl so that only part of it is in the liquid. After 10 minutes, take a look at the nails. Why did the pennies look dirty before I put them in the vinegar?
Why did the vinegar and salt clean the pennies? Why did the unrinsed pennies turn blue-green? How did the nail and the screw get coated with copper? Dip your old toothbrush into the soapy water so that it is thoroughly soaked. While holding the penny with one hand, use the soapy toothbrush to scrub the dirt and gunk off the surface of the penny. Rinse under warm running water and dry with a soft clean cloth. For this method, you will use a commercially available cleanser called Bon Ami.
If you can't find this exact brand name, you can substitute baking soda. In our experience, the name-brand cleanser produces the best results.
This fun process begins by taking the powdered cleanser or baking soda and placing it in a small bowl or container. Start mixing small amounts of water into the powder until you have a paste-like consistency.
Pick up a small amount of the paste on your thumb and forefinger by dipping them into the container. While holding the penny with your other hand, rub the mixture onto the front and the backside of the penny at the same time.
Using small circular motions produces the best results. Rinse the penny and your fingers under clean running water and dry with a soft cloth. While this method will remove surface contamination, it may not make the copper penny bright. You may want to use one of the above methods such as lemon juice or ketchup to brighten the surface of the copper.
Additionally, be careful how many pennies you do at one time. The constant scrubbing of the cleanser or baking soda may cause abrasions on your fingertips. If your coins have glue, adhesive , tape residue or any unidentified gooey substance on the surface, this is your best bet to remove it. Depending on the type of metal that your coin is made out of, Goo Gone may also restore the shiny surface to the coin. If the shine is not restored after you use Goo Gone, use the soap and water, or the pencil eraser method as described above.
Pour a small amount of Goo Gone into a small bowl. Dip a corner of the paper towel into the liquid. While holding the coin on a flat surface rub the Goo Gone onto the surface of the coin. If the foreign substance on the coin is not easily removed, place the coin in the small bowl and let it soak for a bit. Then try rubbing the foreign matter off the surface again.
Finally, wash the coin using the soap and water method mentioned above to remove any Goo Gone residue left on the surface of the coin. If the residue is difficult to remove, some rubbing alcohol purchased from a drugstore can be used to remove stubborn residue.
Actively scan device characteristics for identification. How does it work? To make it a true experiment, you can try to answer these questions: 1. Will other acids like lemon juice or orange juice work as well? Does this cleaning chemistry work on other coins? Do other amounts of salt make a difference in the chemistry of the experiment? What is different about the pennies?
What is the same? Older kids: In this experiment, you left the penny in the vinegar for ten minutes. What do you think would happen if you left it in for 30 seconds? What if you left it in for an hour? What would happen if you put only part of the penny in the vinegar? Make a guess and test these ideas with other pennies. If you run out of vinegar, you can also use other acidic liquids, such as lemon juice or pickle juice. See how they compare! View our Privacy Policy and Terms and Conditions.
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