Solution to Chemical Mystery #6 is presented. Also, concepts related to the chemical can crush demo are briefly discussed.
Can you figure out how this experiment works?
Flinn Scientific has a great elearning video series. Many of the videos have master teachers demonstrating some great labs and techniques that they do in the classroom.
This year in the midwest United States, winter has been a fickle friend. I haven’t seen the same amount of snow or ice as in recent years, but I still made sure I was prepared for it at our home. I went to my local big box hardware store in December and contemplated buying rock salt (NaCl), and NaCl/calcium chloride mixture, or just calcium chloride. Growing up my dad had switched entirely to calcium chloride because it was less damaging to the brick pavers leading to our porch and backyard. In fact, calcium chloride is generally much safer toward plants and soil than NaCl. Even though calcium chloride is much more expensive than rock salt (it was about twice the cost for 10 pounds more), that what’s I chose. Why?
This past summer our conversations turned to, “How can we improve our instruction to try and prevent the initial misunderstanding?” We had all read Dorothy Gabel’s article Improving Teaching and Learning Through Chemistry Education Research: A Look to the Future. We were intrigued by the author's description of the three fold system of representing concepts in chemistry.
I have always struggled teaching the concept of bonding. What is a chemical bond? Is it just covalent or ionic? What about hydrogen bonds? Are those real bonds or just attractive forces pretending to be bonds? If they are not official bonds, what do we call them? How about intermolecular forces? How are those different from salt crystals that attract to other salt crystals but are called ionic bonds? How about "electronegativity"? If there is a metal nonmetal compound but it is just shy of the "cut off" for the difference between polar covalent and ionic, what type of bond is it? Essentially, as I got confused over the years, this translated into confused students and rushing on to get to the next unit in an attempt to cut my losses.
At Chem Ed 2015, a teacher from Texas showed me this quick and dirty way to do a distillation that the kids can do. I forgot her name. "Lady from Texas", let me just say "thank you". If you are reading this, please shoot me an email and I will be more than happy to give you credit. It worked really well.
What is your definition of the term “mole” in chemistry? Many articles have been written about the term and the confusion surrounding it. It was not considered an SI unit (with an IUPAC definition) until 1971. IUPAC is considering a change to the 1971 definition. There has been discussion about whether the SI definition of the mole as determined by IUPAC necessarily needs to be identical to the definition used by chemists and teachers. This article provides a short list of some recent JCE articles discussing the change and what it might mean for teachers while also considering some misconceptions related to the mole in chemistry class.
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!