In Chemical Mystery #7, a can of Coca-Cola was observed to sink in one container of water and yet float in another! This trick made use of the fact that the density of water changes with temperature.
Q: Does an unopened can of soda pop float or sink in water?
A: It depends!
See if you can figure out what is happening in this twist on the classic floating-and-sinking soda can experiment.
Inspired by Tom Kuntzleman*, I started using mysteries in my chemistry curriculum this past year. The first mystery I shared with my students was burning water. While my magician skills aren't perfect, I was able to get the students asking questions and proposing hypotheses. For my IB students, it really allowed me to delve into a number of topics (e.g. combustion, intermolecular forces, polarity, density). And thus an idea was born: Using one mystery per topic. In this blog post I'll discuss my beginning effort to find or develop a mystery for each topic within the IB Chemistry curriculum.
Solution to Chemical Mystery #6 is presented. Also, concepts related to the chemical can crush demo are briefly discussed.
Can you figure out how this experiment works?
How can I engage my students (and myself) for the last half of the semester? I read recently that the human attention span in 2015 is 8.25 seconds(link is external), which is down from 2000’s 12-second span. Currently, we are just beneath goldfish, who can attend to one thought for 9 seconds. I’m not sure of the methods of the research study, and I maintain a level of healthy skepticism. However, I admit my thoughts often spring from topic to topic like a bubble gum machine bouncy ball.
One of my favorite things to talk about with my colleagues is the use of lecture demonstrations in teaching. There seems to be a push in my district to stop using chemicals whenever possible and get to computer simulations and video in place of wet chemistry. I don’t think they are thrilled with me since I can’t envision ever taking the chemistry out of chemistry.
Flinn Scientific has a great elearning video series. Many of the videos have master teachers demonstrating some great labs and techniques that they do in the classroom.
Most chemical educators will agree that exciting demonstrations are excellent motivators to create interest in science. They are also a way to create interest in the community, motivate the student-demonstrators, and perhaps to make a little money to support special activities of an ACS Chem Club. Chemical demonstration shows, organized around holidays or other special occasions have a long and honored history. Pacifica High School (Garden Grove, CA) took its inspiration from the lecture-demonstrations of Michael Faraday, given during the Christmas holidays of 1860-61. (The Chemical History of A Candle).
How does the blue to white color change occur in the foam of Scrubbing Bubbles or KABOOM Brand cleaners? Watch this video and find out.