Erica Jacobsen shares highlights from the June 2017 issue of the Journal of Chemical Education that are of special interest to high school chemistry teachers.
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.
30 minutes including preparation time.
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.
15 minutes of prep time and 20 minutes of class time if you have multiple hoods available for students to use. I only have one hood, so I have another activity for students to complete while two groups rotate through the lab over two 60 minute class periods.
A description of a quick and easy lesson that is sure to add some spark into your next lesson on stoichiometry.
Fostering Engagement in Nanotechnology The Feburary 2014 issue of the Journal of Chemical Education is now available online to subscribers at http://pubs.acs.org/toc/jceda8/91/2. The February issue features articles on nanotechnology in the areas of public engagement, instrumentation, and laboratory experiments.
Students proceed through a prior knowledge activity, practice creating and using a voltaic cell and use of a model designed to simulate the particulate level activity within a voltaic cell. The teacher checks for student understanding at specific points as groups work together. A discussion follows to help clarify ideas.
About one 60 minute class period for lab and manipulative procedure.
The reaction of a copper penny (minted pre-1982) and concentrated nitric acid (15 M) is shown. Red-brown nitrogen dioxide is generated and some of the copper dissolves to form a blue solution of copper(II) nitrate.