The solution to Chemical Mystery #9: Liquid Nitrogen vs. Dry Ice is presented. Why does liquid nitrogen launch the bucket so much higher than dry ice and water?
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?
Ringing in Volume 94
The January 2017 issue of the Journal of Chemical Education is now available online to subscribers. Topics featured in this issue include: NMR spectroscopy; examining assessment; inquiry-based practices; cost-effective instrumentation; miscibility demonstrations; innovative laboratory experiments; from the archives: lightsticks.
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.
15 minutes of prep time and 20 minutes of class time if you have multiple hoods available for students to use. I only have one hood, so I have another activity for students to complete while two groups rotate through the lab over two 60 minute class periods.
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.
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.