I bet you’ve wondered if all chemistry majors do is play in the lab and make cool stuff all day long. Well, with the exception of all the hardcore studying that goes on outside the lab, being a chemistry major is exactly like that! Lab days are some of my favorite days because I get to see and do some really mind-blowing reactions. For this week’s post, I wanted to share just a few of my favorite chemistry experiments, some that I’ve actually done in the lab at LMU and some that I only wish I could do!
The formation of slime is a classic first-year chemistry experiment that demonstrates the properties of acids and bases. Combining hydrochloric acid and the base sodium hydroxide with borax and polyvinyl alcohol creates a substance with the texture of Silly Putty. You can stretch it, roll it, and bounce it, and it lasts for a very long time. When we performed this experiment in my freshman General Chemistry lab, we even added our choice of food coloring for an added bit of fun.
One of the many carbon compound classes discussed in Organic Chemistry is the ester, which contains a central oxygen atom surrounded on each side by hydrocarbon (hydrogen and carbon) groups. Combining a carboxylic acid compound with an alcohol, both of which have oxygen in their structures, causes a rearrangement of the atoms into an ester shape. In my Organic Chemistry lab, we mixed acetic acid and isoamyl alcohol to create the ester isoamyl acetate, known commonly as banana oil. Esters are important in industry because they are some of the key components in fragrances. Banana oil, naturally, is what gives bananas their sweet, fruity scent. I can always tell when the latest crop of organic chemistry students are discussing esters in class because the entire lab floor in the Hamilton Math and Science Building smells of bananas!
This experiment absolutely blew my mind because nearly all of the experiments I had done in the lab prior to this had involved either mixing two liquids, or dissolving a solid in a liquid. I had always assumed that two solids did not ever react together because none of my chemistry instructors had ever discussed the possibility. But in Organic Chemistry, I found out first hand that this actually can happen, it’s just a little time consuming. We reacted potassium iodide and lead nitrate, two white powders, and they instantly formed lead iodide, a bright yellow powder. It took a little work and manipulation to get every bit of each solid to react, but both powders were completely consumed in the reaction. In the video below, aqueous solutions of the two powders are used. Notice how much faster the reaction happens when the particles are suspended in water.
This Analytical Chemistry experiment was an observation of fluid properties like viscosity, or resistance, under different conditions. We reacted a variety of different substances, including borax, polyethylene oxide, and sodium dodecylbenzenesulfonate (try saying that five times fast!) in different combinations to see which ones yielded the thickest and most stable foam. This reaction has many important industrial applications in the manufacture of substances like shaving cream.
This actually isn’t something that I’ve done in the lab myself, but I saw a video of it and was amazed so I thought I would share. Oscillating chemistry reactions run in a loop. They start out a certain color, transform to another, then return to their original color and go through the process again and again until they eventually reach an endpoint. The reason for this is the periodic change in concentration throughout the reaction process, a concept known as non-equilibrium thermodynamics. A popular oscillating reaction is the Briggs-Rauscher reaction, shown in the video below, which combines hydrogen peroxide and an iodate compound, using manganese as a catalyst.
Screaming Gummy Bear
I have, in fact, seen this reaction take place, but it was at a weekend program at a community college that I participated in during middle school. Because I was so young and knew very little about chemistry at the time, and also because this reaction can be a little dangerous, I had to stand a few feet away while the instructor worked behind a chemical fume hood (You can do it out in the open, like the class in the video below, but we chose to minimize the amount of smoke by doing it under the hood). What happens is that the sucrose in the gummy bear reacts with very warm potassium chromate, releasing lots of energy and creating a lot of noise, almost as if the poor bear is screaming. (Now that I think about it, this is really a pretty creepy experiment!) The result is a really neat demonstration of the explosive power of metallic compounds.
This concludes my first installment of “Crazy Chemistry”! I hope you enjoyed it, and hopefully there will be more to come in a later blog post. If you’d like to be updated whenever I post, you can subscribe to my blog via email using the button in the drop down menu. Thanks for reading, and be sure and comment below with any thoughts or questions!