Are you familiar with the dynamic density bottle experiment? This interesting experiment was invented by Lynn Higgins, and is sold by various science supply companies. Two immiscible liquids (usually salt water and isopropyl alcohol) and two different types of plastic pieces are contained within a dynamic density bottle. The plastic pieces display curious floating and sinking behavior when the bottle is shaken. You can find out even more about how a colleague and I have explored the experiment by attending our session within the ChemEd X Conference: Chemistry Education for the Next Generation.
Like most chemistry teachers, one of the first things I go over in the beginning of the year is unit conversions. Students come into my class with all sorts of prior knowledge concerning unit conversions; some good, some bad and some downright ugly.
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. See the video below.
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.
Each spring my Local Section of The American Chemical Society (ACS) hosts a rigorous two part exam as part of the selection process for the The International Chemistry Olympiad (IChO) IChO is an annual international competition for the world’s top chemistry students. Each year, nations from all over the world will send teams of four to compete for top honors.
Effective Student Engagement
The September 2015 issue of the Journal of Chemical Education is now available online to subscribers. This issue includes articles on flipped classroom; introductory and general chemistry; organic chemistry activities; biochemistry demonstrations and labs; computer-based learning; chemical education research; from the archive: chemistry in context.
The video displays a neat trick you can do for your students. What do you suppose is the secret behind this trick? Hint: >It has to do with chemistry!
Although many students have been exposed to the concept of density before reaching my Chemistry class, I always start the year with this POGIL-like activity.
Approximately one hour including the debrief (I recommend holding a whole-class discussion for the summarizing questions that follow the What is density? activity and a selection of mathematical computation problems from the How can you calculate density? activity.)