For Carnegie Mellon's Karen Stump, Independence Day brings to mind two memories: waving sparklers as a newlywed at the Bicentennial festivities in Wildwood, N.J., and Introduction to Chemical Analysis classes.
As a chemistry professor, Stump says she is continually looking for ways to involve students in the discipline in a way that is useful and interesting to them. Sparklers happen to be the source of a consistently popular project in her introductory class.
"I think that many times people of all ages forget to marvel at the wonders of the world around us," she said. "I think too often as we get older we silence that inner child that truly marveled at things like sparklers and fireworks and wondered, 'how do they do that?'"
Student teams are able to learn a range of lessons from the Fourth of July favorite.
"The student teams generally make their own sparklers but then also perform analyses on commercial sparklers," said Stump. "They might investigate the oxidizing capability, or more often the metal concentrations, before and after burning."
Like any fire, Stump says, you need a heat source. The sparkler supplies a fuel and an oxidizing agent, and the fuel is what burns.
"In the sparklers we make in the lab, we use a paste of potato starch as both a fuel and the binder, which holds the components of the sparkler together and helps it adhere to the iron wire," she explained. "When it burns it primarily forms carbon, the black residue left on the wire after burning. The oxidizing agent is a compound that, when it decomposes, it supplies additional oxygen to the fire. So you get more vigorous burning."
Different colors can be generated by adding metal salts that burn with a color.
"Sodium chloride, for example, in a flame burns yellow while strontium nitrate burns a brick red color," she said.
Team projects like this are an important component of the class for many reasons, notes Stump.
"Much of academic lab work in chemistry is designed to give students experience with techniques, which is critical in developing accurate and effective approaches that can be used in academic and industrial research and analysis," she said.
The course is project-oriented with a focus on quantitative analysis. In other words, students use investigative methods to determine "how much" of something is present in a sample. And there's usually a theme.
"We have had semester-long themes of wine analysis, vitamin analysis, food chemistry, and are currently working on a fall course with a focus on forensics," she said. "The students can be so incredibly creative when given the opportunity, and they engage with the material in a much deeper way."