The cover photograph of the November 2014 issue of Chem 13 News (pictured above) is more interesting than it might appear at first glance. (Consider this demonstration 1.)
The use of natural gas (methane) and propane as fuel gases exemplifies numerous areas of general science and general chemistry: intermolecular forces, states of matter and changes of state; heats of vaporization; liquid–vapour equilibrium and vapour pressure; stoichiometry and heats of combustion; gas laws; carbon dioxide emissions and climate change.
Chemical reactions are the most exciting part of chemistry class. Over the past five years I have developed an experience-based chemical reactions unit that features instructional videos coupled with a small group laboratory experience, whole-class demonstrations, and an interactive “demo test” as a final assessment.
Citric acid is a user-friendly, inexpensive, water-soluble, crystalline solid carboxylic acid. In comparison to using hydro-chloric acid solutions, using solid citric acid and its solutions in water is safer and more convenient. For inexperienced students its titrations against strong base are easier to perform.
This article was first published online on the blog called Educational Theory and Practices, which is maintained by Stuart T. Haines, a professor at the University of Maryland School of Pharmacy, Maryland. The blog is “random musings by people who think about educational psychology and the practice of instructional design.” We recommend you visit this blog for lots of interesting reading.
Each year after the dust has settled, Carey Bissonnette at the University of Waterloo reviews the CHEM 13 NEWS Exam statistics. As part of an item analysis, a point-biserial correlation coefficient is calculated for each of the 40 exam items (questions). Basically, this is the correlation that quantifies the relationship between how students do on each individual item versus the overall exam.
Your students may find it interesting to determine and compare the acid content of individual sour hard candies. In addition to doing the titration analysis and the calculations, reported as the percent by mass of citric acid, students can learn about the technology of candy making.
Elaine “Lainey” Williams learned the procedure for the thermoplastic shaping activity, tried out various combinations of the dyes, instructed her classmates and shared this activity with 4th to 6th grade girls who recently participated in the FEMMES (Females Engaged in More Math, Engineering, and Science) Capstone event. The following are Lainey’s thoughts about learning the procedure, the underlying chemical concepts and sharing the thermoplastic activity with others.
The catalytic oxidation of tartrate ions by hydrogen peroxide has been a staple of the Duke chemistry instructional program for many years. The demonstration clearly and colorfully brings to life the textbook description of what a catalyst is and how it enables a reaction to proceed at a faster rate by becoming involved in the reaction, yet in the end returns to its original state.
How many of you have heard of para-chlorobenzotrifluoride (PCBTF)? Or to give it a more systematic name, 1-chloro-4-(trifluoromethyl)benzene. In a previous article, I described the hazard of the xylene-ethylbenzene hydrocarbon mixture often used as a solvent in varnishes and glues.