The lab was a success as I watched startled students produce the so-called barking dog sound as they combusted the hydrogen gas in their inverted test tubes.
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It’s the end of one semester and the beginning of another. Final exam week. For the first time in my teaching career, I had my grades caught up and posted prior to the beginning of final exams. This gave me time to reflect and plan ahead.
Whether you are introducing collision theory or something more demanding like reaction order, the reaction between sodium thiosulfate—Na2S2O3 and hydrochloric acid can provide a consistent, accurate, and engaging opportunity for investigating these topics.
Students will build models of isomers while the instructor walks around from station to station to critique the models. If the model is incorrect, the students rebuild until they get it right. The paper that accompanies this assignment is very easy to grade.
There are many places online to build a DIY Hoffman apparatus. The ACS offers an electrolysis of water lesson that includes a hand made Hoffman apparatus(link is external) as part of a unit on energy that I used as a resource.
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?
Looking over my student's papers, there may have been more misconceptions created because of the way I planned the curriculum. In all of the experiments students can see and observe that not all of the crystals or material dissolves yet the water starts to conduct. In their minds there is evidence that they believe either something DOES dissolve or it does NOT. Clearly, partial dissolving is initially too much to consider.
Chemical kinetics is one of the five challenge areas in AP Chemistry. My students and I have been working our way through one of the teaching and learning activities called Concentration vs. Time. The graphical analysis, guided-inquiry questions, and application to past and future content are seriously challenging, and my students report higher levels of understanding than in past semesters.
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?
Highlights from the January 2017 issue of the Journal of Chemical Education of special interest to high school chemistry teachers.