Investigating Chemical Reactions

We invite you to try out Imagination Igniter # 3 -- Investigating Chemical Reactions

Be sure to share your pictures or video with us!

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Transcript of video:

Imagination Igniter #3 -- Investigate chemical reactions

These are both pennies. They are both worth one cent, but one is very shiny and the other is not.

I wonder why?

Let’s take a closer look at the dull penny.

Do you see the year on that penny?  It’s been circulating since 1940.

Over that long time, the oxygen in the air has reacted with the copper in the penny.

This reaction creates a new substance called copper oxide that now coats the penny 

and keeps us from being able to see the shiny surface below.

When we look up close, you’ll notice that the shiny penny has only been in circulation for about a year.

To make the old, dull penny shiny again, we’ll create a chemical reaction to dissolve the copper oxide.

For Imagination Igniter #3, you’ll need two dull pennies, lemon juice, a bowl, water, and a timer.

Your pennies should be both about equally dull.  We’ll call one the control penny and not do anything to it during this investigation.  And the other penny is the one we’ll investigate with.

The juice from a lemon is acidic.

In fact all, citrus fruits have acidic juice, but the lemon is the most acidic.

That’s what makes a lemon taste so sour!

Squeeze or pour some lemon juice in a bowl.

 And put your investigation penny into the lemon juice

And set a timer for 5 minutes and wait.

After 5 minutes we want to stop the reaction so you’ll need to rinse your penny in water.

Dry off your penny and compare it to the control penny.

Do they look different now?

The easiest comparison is to look at before and after which we’ve done with these two pictures of the same penny.

The lemon juice dissolved the copper oxide and made our old penny shiny again.

You know, these chemical reactions remind me of one of our E-skills -- Collaboration. 

A chemical reaction occurs when at least two things work together and create something different.  

One of the most important and powerful parts of collaboration is that,  with the group, you do better work than any one person would do by themselves.  

Through our investigation so far we’ve learned that lemon juice can remove the copper oxide from a penny.  Now let’s try an experiment.

With some more dull pennies, we’re going to experiment with two variables -- what we soak the penny in and how long it stays there.

For variable one you can try these different substances:  Soap and Water, Vinegar, Vinegar and Salt, Ketchup, and Lemon Juice

Wait, did she say ketchup? 

Remember that we’ve learned that acidic substances can remove copper oxide.  We know lemon juice is acidic -- so is vinegar.  Check out the ingredients of ketchup!

Your time variables could be 5 minutes, 10 minutes, 15 minutes, or really however long you want to try.

Remember that for an experiment, we’ll want to change only one variable at a time.  

Try putting a different, but about equally dull, penny in each different substance for 5 minutes.  

Compare the results after you rinse off the pennies.  

I wonder, does this experiment work with other coins?

Give it a try, then email your results to

Or share with us on social media.