Did you know there is a simple test you can do to see if an alkaline battery is fresh or dead? All you need to do is bounce the bottom of a battery onto a hard, flat surface. Guess what causes this difference in bouncing ability between fresh and dead batteries? Chemistry, of course!
I found a version of this demonstration online a couple of years ago. I admit, when I first tried it with my class it was mostly for a crowd pleaser to demonstrate the activity series of metals, but I then became very intrigued by the processes occurring. The original source only referenced the “single replacement reaction” between Mg(s) and AgNO3(aq). Therefore, when I saw a grayish product (silver) I was not surprised. However, I was surprised by the white flash and the production of a white product, which were reminiscent of the classic combustion of magnesium demonstration. This led to some research and my conclusions that follow. Read through to the end and you will find a video of the demo.
The lab was a success as I watched startled students produce the so-called barking dog sound as they combusted the hydrogen gas in their inverted test tubes.
I have used several different versions of the Silver Mirror or Tollen's Test lab. I am sharing the method that has proven to be the most reliable for me. The solutions should be made fresh, the directions must be followed closely and timing is very important. I like the fact that relatively small amounts of the chemicals are required, but as always you must be vigilant with safety precautions.
My IB seniors are just wrapping up our unit on electrochemistry and redox. This has always been a challenging topic within the IB curriculum. Admittedly, electrochemistry has not ever been my strong suit either, so this year I aimed to strengthen the unit with two additional demonstrations.
Looking for an easy, hands-on experiment to use in your classroom at the beginning of the school year? In the June, 2013 issue of the Journal of Chemical Education, Isao Ikemoto and Kouichi Saitou describe a simple experiment to demonstrate the electrolytic dissolution of copper ions from a copper electrode. This experiment can be conducted using only items that are easily obtained around the home or in grocery stores.
This lab was written as part of the Target Inquiry program at Grand Valley State University in Michigan. Students build an electrochemical cell, learn about the symbolic equations used in electrochemistry and manipulate a model representing the particulate level of what is happening during the electrochemical process.