Use Chemical Reactions to Introduce Financial Literacy

Now, if you have already collected a bunch of pennies for the previous lemon battery experiment, you might as well do this experiment too.  This experiment will make pennies look new, but you can make them extra dirty–or oxidized before you make them shiny.  This experiment is quick and easy and has high impact.

First, to make your pennies oxidize or turn green, put your pennies in a shallow plate (see below) somewhere on a paper towel.  Pour just enough white vinegar to let the pennies sit in the vinegar.  You don’t want the vinegar to cover the pennies because you want the oxygen to reach them.  You could turn the pennies over after they touch the vinegar so that both sides are able to touch the liquid.  The combination of vinegar and oxygen will make them green.  I have only done this when leaving the pennies for several hours or overnight, but the reaction will still happen with less time.   The oxidation just won’t be as noticeable if done for an hour or two.

Note:  I only used pre-1982 pennies which are mostly copper as opposed to new pennies which are filled with zinc and only coated in copper.  This reaction I believe will still work with new pennies because the copper is on the outside.

Here is the end result below…they are all dried off.  When doing this with children make sure you let them know that the pennies are not “rusting”, but that this is a chemical reaction between the oxygen and the vinegar called oxidation.

Now this is what I did in my lesson.  I gave the kids an old green penny and a new penny (made 1982 and after).  I told them to drop each penny on the table and listen to the difference in sound.  Allow the kids to describe the differences in the pennies.

Next, I handed each child a small cup–in this case they are those little medicine cups.  I had each child drop their old green penny in a cup and walked by to pour lemon juice just barely over the top of the penny.  Then I had the children slide the cup from side to side to wash it in the lemon juice.  I bought my lemon juice at Wal-Mart for about $2.  If you have the leftover lemons from the lemon batteries, that juice will work too, but it is just easier to buy the lemon juice already made.

What is interesting is that the oxidation washes off in the cup and the lemon juice turns green.  This is a great time to bring in the social studies aspect of the Statue of Liberty turning green from the oxidation.

I took this science experiment a step further and discussed inflation with the students by showing them a a video like this one about penny hoarders.  We further discussed how the prices of goods and services are rising.  Next, I give the students a chart and have them find the purchasing power of a dollar over time.  We use this website to calculate the purchasing power of a dollar.  They watch inflation from 1913 to the current year.  This is very astonishing to them, and will organically lead to great discussion.  Further, I give them a long term homework assignment and tell them that they are to pick one grocery store item and watch the price over time (this could take years).  They are to see if the price of their item goes up or down and keep a record of this.

I hope you can enjoy using science to teach financial literacy in your classroom, too.