Chemistry Experiment Cleaning Coins

Materials Needed:
Old Coins
1/4 Cup of white vinegar
1 Teaspoon Salt
Non-metal Bowl
Water

Objective:
Clean the old and dull pennies using vinegar to make them "blink" and shine again.

Procedure:
1) Pour the vinegar into the bowl and add salt.
2) Stir the solution.
3) Put 4-5 pennies inside the solution.
4) Wait for about 10 seconds.
5) Take the pennies out and rinse them in water.
6) Observe (You should be able to notice the coins become shiny again).

Reason:
Vinegar is an acid and reacts with salt to remove the dullness or remove copper oxide which was making the coin dull.

Now, some questions to ponder about...

1) Will other acidic stuff like lemon and orange work in this experiment?
2) Can this experiment be done on other old coins and work as well?
3) Does it matter if I add more salt or more vinegar in this experiment? Does it affect the results?

Reflections:

This experiment clearly shows the reaction between acid and salt- solution to removing copper oxide. This experiment is very useful and interesting as a teaching tool (if possible) as just talking about chemical equations in class can be very boring. Doing the experiments for the students to see, they could understand the lesson better. I hope to have more experiments in time to come, maybe to prove chemical equations or just to show students how the chemicals really react with each other. This kind of experiment would be able to capture the attention of the students, making it a fun learning experience for the students!\

Source: http://www.sciencebob.com/experiments/pennychem.php