My first year teaching chemistry, I was looking for a soap-making lab or activity that I could run in my chemistry class with 25-30 students working at the same time. I usually do this activity right before spring break, as it provides enough time for the soap to harden and cure (high school students are impatient to use their soaps right away, which you should not do with cold process soap). I have used the activity at different points in the curriculum: during intermolecular forces during acids and bases, and during stoichiometry. Although I know teachers who use soap making as a project during their stoichiometry unit, I chose to not emphasize the calculations as it would require more time than I have available. Simply making the soap easily fits in a 45-minute period.
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.
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.
Just this week I'm reviewing equilibrium with my IB Chemistry seniors after they finished some summer study on the topic. One of our classes was spent manipulating a classic equilibrium involving copper ions and a copper-chloride complex ion.
Students combine sodium carbonate and hydrochloric acid generating carbon dioxide gas which is allowed to escape. They measure the actual yield of carbon dioxide produced (missing mass), calculate the theoretical yield using stoichiometry, and then the percent yield. Students understand that 100% yield is the most appropriate answer (based on the Law of Conservation of Mass), so after considering the meaning of significant figures and the uncertainty of their measurements they are asked to decide if they did (or did not) get an answer that might indicate the validity of the Law.
Suitable for Online Instruction: An independent study on the chemistry topic of coordination compounds and complex ions suitable for AP Chemistry and first-year college chemistry students is presented. Originally published 3/20/2014.
This laboratory exercise accompanies the article "A guided group inquiry lesson on coordination compounds and complex ions". The laboratory serves as part of an extended exercise on the chemistry topic of coordination compounds and complex ions. The entire lesson as described in the article also exposes students to how chemical research is conducted and the conflicts and uncertainties that lead to new theories and discoveries.
I expect that most high school chemistry teachers assign some type of laboratory related to types of chemical reactions including synthesis, decomposition, single replacement and double replacement reactions. I have used several published versions, but I am sharing my modifications.
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.