What is the science behind cleaning pennies?
What is the science behind cleaning pennies?
Here’s what’s happening: The oxygen in the air and the copper in the pennies form an oxide that coats the pennies and makes them look dirty. The acids (usually vinegar – acetic acid) break the copper oxide free from the penny. As we have seen experimentally, acid alone does not clean as well as acid and salt.
What cleans a penny better experiment?
Pour ½ cup of vinegar into the bowl and add 2 teaspoons of salt to it. Hold a penny halfway into the liquid for about 15 seconds and remove it. Make some observations. Put the rest of the pennies into the vinegar/salt solution and wait 10-15 minutes.
What kind of juice cleans pennies best hypothesis?
You can “clean” a penny a little bit and very slowly with lemon juice or vinegar (mild acids), but put a dash of salt in the lemon juice and the penny will turn orange with a quick rub.
What happens to the pennies in the experiment?
When you place the pennies in the salt and vinegar solution, the acetic acid from the vinegar dissolves the copper oxide, leaving behind shiny clean pennies. The copper from the copper oxide stays in the liquid. You could use other acids instead of vinegar, like lemon juice.
Is cleaning pennies a chemical reaction?
This acid removes oxidation from pennies. Removing the copper oxide is a chemical change. The copper molecules in the vinegar and salt solution settle on paper clips after a period of time, but wipe off easily. This is not a chemical change.
Is a penny turning green a chemical change?
As the penny dries and is exposed to the air, a chemical reaction occurs and the penny turns green! The green compound is called malachite.
Why does salt and vinegar clean a penny?
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!
What substance will clean a dirty penny?
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.
Why does lemon juice clean pennies better than vinegar?
Vinegar has a pH level of 3.0, while lemon juice has a pH level of 2.3. This means that lemon juice is a slightly stronger acid than vinegar. The stronger the acid, the better it will clean copper pennies.
What liquids can clean a penny?
For many pennies, one tablespoon (15 g) of salt in 1/2 cup (4 oz) of vinegar will get the job done. Stir the mixture to dissolve the salt. If you don’t have vinegar, use lemon or even orange juice. Copper oxide (the gunk on your pennies) dissolves in weak acid, and that’s just what all three of these liquids are.
Is cleaning pennies a chemical change?
What was the control in the penny experiment What is the purpose of this control?
The control is the penny without soap. If a penny is covered with soap, then it will not hold as many water drops because the soap does not allow for adequate surface tension to occur.
Is cleaning a penny a physical or chemical change?
Why does lime juice clean pennies?
Pennies are made out of a metal called copper. The copper mixes with oxygen, the same gas that we breathe. This cause something called oxidation and makes the penny look dirty. Lemon juice has acid in it that removes the dirty color or oxidation and makes the penny nice and shiny again!
Is cleaning a penny a chemical change?
What is the chemical reaction between vinegar and salt?
The combination of salt and vinegar creates sodium acetate and hydrogen chloride. This chemical reaction will take an old penny and shine it like new.
How do you clean coins science project?
In one cup, pour enough vinegar to cover the penny. In the other cup, pour enough liquid soap to cover the penny. Wait at least ten minutes. Remove the pennies, rinse them in water, and rub them with a paper towel.
Why does vinegar make pennies turn green?
Why did the unrinsed pennies turn blue-green? When the vinegar and salt dissolve the copper-oxide layer, they make it easier for the copper atoms to join oxygen from the air and chlorine from the salt to make a blue-green compound called malachite.
Why do pennies change color in vinegar?
When copper is exposed to oxygen, it forms molecules called copper oxide that make pennies look dirty. Pouring vinegar over the pennies helps break up this copper oxide and expose the pure copper on the penny. As the penny dries and is exposed to the air, a chemical reaction occurs and the penny turns green!