In Chemical Mystery #10, plastic straws are observed to “magically” change color when waved in the air. Check out the explanation and the video.
As part of a two-week Chemistry Modeling Workshop™ in Houston, TX, I had the opportunity to read the Journal of Chemical Education article “When Atoms Want” by Vicente Talanquer of the University of Arizona. I researched Dr. Talanquer and discovered he created a collection of simulations called Chemical Thinking Interactives (CTI). These digital tools illustrate many chemistry topics with a focus on the particulate nature of matter.
In this simple trick, colors are made to "magically" appear and disappear on a straw. This science experiment is very easy to do...if you know your chemistry!
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.
A 2L soda pop bottle is filled about one-third full with either liquid nitrogen or solid carbon dioxide (dry ice) and water. The bottle is sealed and a plastic bucket is placed on top. Do you think the liquid nitrogen or dry ice and water will make the bucket go higher? Can you explain the results using chemistry?
Improving Student Understanding
The December 2016 issue of the Journal of Chemical Education is now available online to subscribers. Topics featured in this issue include: synthesis in the laboratory, examining and using a flipped classroom, improving labs through multimedia-based and student-directed learning, using applied math for better understanding, improving student understanding of thermodynamics, inclusive chemistry teaching, using manuscript review for assessment, climate chemistry, spectroscopy experiments, performing safe demonstrations.
I have a confession: thermodynamics is not my strong suit. The data set I got from the College Board confirmed my lack of confidence in the summer of 2015. With the hope of improvements, I spent some time revamping my thermo unit and I implemented it near the end of last school year. I will share an activity that I feel was quite formative for students and for me in making connections among thermodynamic principles and equilibrium.
Engaging Student Interest and Inquiry
The September 2016 issue of the Journal of Chemical Education is now available online to subscribers. Topics featured in this issue include: copper chemistry; safety; using brewing to teach chemistry; 3D-printed models; learning using games; open-ended approaches to teaching; innovative methods to teach biochemistry; polymer chemistry; organic synthesis labs; teaching physical chemistry; chemistry field trips.
Solution to Chemical Mystery #6 is presented. Also, concepts related to the chemical can crush demo are briefly discussed.
Thinking Like a Chemist
The May 2016 issue of the Journal of Chemical Education is now available online to subscribers. Topics featured in this issue include: assessment & learning theories, science literacy & chemical information, engaging young chemists in chemistry, analysis of real-world samples, organic chemistry in the classroom and lab, computational chemistry in the laboratory, thermodynamics, kinetics projects, understanding hydrophobic & hydrophilic materials.