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Vocabulary Word of the Week: Acidic

The experiment calls for vinegar but because lemons, oranges and tomatoes are also acidic, you can try them out too.

Today’s vocab word of the day is acidic! Acids are sour substances. Their pH value is lower than 7. An example of acidic substance is vinegar, which we will be using in our experiment.

Have you have seen an older penny that is no longer shiny? Well, today you can learn how to make your pennies shiny again!

On the right you see the penny at the start of the experiment. On the right is the penny after the experiment

On the left you see a shiny penny. On the right is an old penny.


  1. A couple older, no longer shiny, pennies

  2. Vinegar (1/4th cup)

  3. Salt (teaspoon)

  4. Bowl (non-metal)

  5. Paper Towels


  1. Pour the vinegar into the non-metal bowl and also add the teaspoon of salt. Make sure to stir it!

  2. Put a few, around 5, pennies in the bowl and wait about 10 seconds

  3. Take the pennies out of the vinegar and wash them in water. They should be shiny!

    Watch the experiment in action

Why does this work?

The mixture of vinegar and salt creates a weak acid, that will react with the dull, outer copper oxide layer of the pennies! The acid removes this layer when you rinse the pennies underwater. However, if you leave the pennies coated in the acidic substance without rinsing them, it actually makes it easier for your pennies to become dull again.

Maariyah Mustafa

Natalie Duerr

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