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?
Show the kids an event. Have them develop a model. Have each kid draw and write about the model and force them to ask themselves if this model can explain the event. As a teacher, first say something nice about it and then look for their misconceptions and use this as a formative assessment. Combine the individual models with others. Slowly build a larger model and constantly ask if this really explains the event.
This is the first isotope activity I have tried where the students can look inside the model that resembled the atom and find information that reinforced what an isotope actually is. Furthermore, the quantitative data forced them to examine beliefs about different types of averages and what the numbers really mean.
You probably know what happens when you place dry ice in water. Do you know what happens when dry ice is placed in acetone or glycerin? Read this and find out!
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.
My IB seniors are just wrapping up our unit on electrochemistry and redox. This has always been a challenging topic within the IB curriculum. Admittedly, electrochemistry has not ever been my strong suit either, so this year I aimed to strengthen the unit with two additional demonstrations.
Solution to Chemical Mystery #8, and...a challenge!
To squash any misconceptions, I would like to say first and foremost I am not a great cook. My husband graciously does most of the cooking in our house. However, as a chemist, I am fascinated by the complex reactions involved in everyday life. Pair this curiosity with the requirement to teach an elective, and the Chemistry of Cooking elective was born.
For years my students would heat the hydrates in glassware, burn themselves, break the glassware and splatter salts and thus their data, all over the lab bench. A few years ago Bob Worley came up with a great microscale technique. Essentially, it takes a used bottle cap without the plastic and this is used as the dish. Next, there is about a three inch machine screw that goes through a drilled hole in the cap. A nut is placed on the screw to hold everything in place and cheap pliers are used to hold the entire assembly over the flame.
Red dye #40 found in strawberry Kool-Aid and various cloth fibers can be used in a very simple experiment that can teach students about intermolecular forces. A video is included that describes the experiment and analysis of results.
