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.
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). The lab practicals on the exams are presented as problems. No procedure is given. Students must use their chemistry knowledge and lab experience to devise a plan and solve the problem. The best part is that the released exams come with lists of materials and equipment, helpful hints to the proctors, and solutions! This is a great source for Inquiry-Based Lab Practicals.
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.
One day during class I presented the disappearing rainbow demonstration and explained the chemistry behind it. After doing so, I had a student ask me if a particular bartending trick called “rainbow shots” was done in a manner similar to the way the disappearing rainbow demonstration is performed.