Monthly Archives: January 2017

Cleaning Pennies!

Last week, we had the first meeting of the semester! After a month off, it was great to get started with Girl’s Science Club again. And what better way than with some chemical reactions! 

First, Jane led a discussion on chemical reactions. One of the girls said, “a chemical reaction is when you mix two things and there is an explosion!”, which I think is great description of chemical reactions based on our previous meetings. We have done a lot of exploding reactions, so this activity was a nice way to introduce a new reaction that cleans rather than explodes.

For this activity, we had the girls make and label three different solutions: (1) water, (2) water + soap, and (3) vinegar + salt.

Then, we each made a hypothesis which solution would clean the dull pennies the best. On my side of the table, the popular choice was water! We put old, discolored pennies in each solution, stirred, and waited. After about 10 minutes, we examined the pennies and found that the vinegar and salt solution cleaned the pennies the best, making them look new! We explained that this was because the vinegar and salt were reacting with the “dirt” (aka copper oxide) on the pennies.

Then, after removing the pennies from the cup, we gave each girl a new nut to put in the already used vinegar and salt solution. After a few minutes, the nut became dull and looked like the old pennies! This was unexpected and exciting!

Overall, the hour was filled with experimentation. Many girls tried solutions we hadn’t suggested, including salt water, salty vinegar, soapy vinegar, etc. They were engaged and curious, which was an amazing way to start the semester!