Tuesday, October 13, 2015

Guest bleg: Novel organic chemistry demos

From the inbox, a good request:
Dear CJ Readers, 
I've been asked for some suggestions on creating a "modern-day" organic chemistry/general chemistry demonstration curriculum.  Basically I'm looking for some fresh ideas on how to make the S in STEM bigger.  This is what I'm looking for:
  1. A "modern-day" organic chemistry demonstration.  I know we've all had experience with making Nylon, silly putty, etc., but was hoping for some new ideas.  
  2. The demos need to be tailored toward K-12, and we are looking for some "hands-on" demonstrations.  Something that students can do on a desk/table.  
  3. We also would like ideas that could be "mobile."  That is we can take the demos from site to site, and/or have the students take part in the demo on a bus or some type of trailer.
  4. Since we're dealing with K-12 the demos need to cover a range of experience.  Older students could work on the more complicated demos, while the younger students can get exposure to more fun experiments.
  5. We are looking at developing some lesson plans as well and are thinking about making a crime scene investigation that students could work out over a course of a couple of days that would introduce some chemistry techniques that are used in the field.  
I know it's asking a lot, but I would appreciate any type of feedback and/or suggestions. 
With today's litigation-eager society, it's hard to come up with useful/fun/exciting organic chem applications for students.  A lot of demonstrations we were exposed to growing up are unable to be performed in today (guncotton for example).  That's why I'm asking for some help from you on a modern approach to organic/general chemistry demos. Thanks for reading, and I look forward to your suggestions.
Signed, NZ 
My very preliminary suggestion - a very long time ago, I did the synthesis of aspirin in a vial, with salicyclic acid, acetic anhydride, complete with TLC.

Readers, I'm sure you can do better than that. Thoughts? 


  1. I remember a really fun quinine metabolism experiment from undergraduate analytical chemistry. (It's memorable because it was a little yucky.) I think you can probably come up with some fun things to do with tonic water and a black light that are unrelated to bodily fluids.


  2. I taught a two day course for high school students that had an aspirin synthesis actually starting from wintergreen oil (methyl salicylate) and also involved looking at degradation of azo dyes catalyzed by steel wool. It essentially is a very simple qualitative analysis test. The dyes of interest are Kool-Aid packets. Some of the common color additives are azo dyes and degrade, others will remain. I thought it was a nice exercise to relate structure and properties. You can even get fancy and talk about kinetics, entropy, and catalysis.

    1. My seniors are doing the opposite right now - starting from aspirin and taking it to ethyl/methyl salicylate. So far they've managed to crystallize the acetylsalicylic acid out of a couple bottles of Dollar Tree aspirin and set up acid-catalyzed hydrolysis to salicylic acid. We're in the process of building reflux apparatus to do the final esterifications - might use ferric chloride complex test to monitor esterification progress. If we make good 'wintergreen oil' we might sprinkle a little of it on sugar and crush the mess in a mortar in the darkroom to see if we get luminescence.

  3. Its old, but for electrochemistry, you can't beat the Zn/Cu lemon battery (or other citrus).

    A newer electrochemistry experiment that would require some rather specialized materials and knowledge, but is do-able and would be very cool, would be to make some enzymatic biofuel cells and watch how their performance changes with different fuels (sucrose, fructose, glucose, coke, etc.), different pH, different temp., etc.

    This is an undeveloped thought, maybe for a physical chemist to contemplate, but would there be away for students to calculate dielectric constants of liquids by microwaving them and measuring the temperatures? For instance, microwave toluene, ethyl acetate, and ethylene glycol each for 5-10 sec., and the three will have very different temperatures. At the very lease you could demonstrate the concept.

    One thing I did in undergrad that I thougt was cool was taking different colored LED's, dipping them in liquid nitrogen and watching how the color changed vs. RT.

    1. Zinc dendrites make a great demo too. Zinc sulfate solution with a bit of sulfuric acid mixed in, zinc sheet anode, run a good 5 amps of current through it to a copper wire cathode. You can grow some very biological-looking foliage that way.

  4. 300 mL DMSO, 0.1g luminol, then 20-35 mL of 3M KOH(aq) in a clear glass bottle gives you a home-made blue glow stick (appropriate as Halloween approaches). It can be quite bright if you don't add too much base (or possibly with more luminol) and is safe as long as whoever is handling the DMSO/KOH has gloves. If you pour some of that solution into a second bottle with fluorescein, you get a fainter orange glow. These can be used to discuss chemiluminescence and energy transfer, as well as acid/base properties. This demo obviously works better in the dark but if you were on a bus, you could lower the bottles into a backpack and that works pretty well. The Tollen's test in an Erlenmeyer flask probably falls into the category of old demos but it is still one of my favorites and has a bunch of concepts wrapped into it (solubility, pH, metal-ligand complexes, redox chemistry), as well as leaving behind a souvenir for the teacher/class. Chemjobber or NZ, I am always looking for some new demos myself so if you hear about any cool new ones that don't show up in the comments here, could you please post them?

  5. I have done some demos in my children's elementary school. I have tried to keep them easy and fun since the kids are still young. The best hands-on one that I have done has been paper chromatography of water-based ink markers. You use coffee filters as the stationary phase and water as the mobile phase. For the younger kids (I did this for second graders), just having them make a dot of a black marker and watch it separate into the three dyes works well and keeps them engaged. Makes a good lesson about color (Is black a color?). With older kids you can have them do a crime scene investigation where the identity of a black pen can be determined using this technique. Each manufacturer uses different dyes to make their black pens so you can determine which one was used in a 'crime', for example.

  6. I recall a demo of making various esters at test tube scale with combining ingredients adding a drop of acid (HCl) stoppering and giving a shake or swirl then opening up and having people ID the smells. May be good info already out there but assume could make it easy and safe after determining which combos do well.
    I also believe showing a crystallization process can be pretty cool especially using seed crystals or flask scratch technique

  7. I find quality, effective organic demos to be challenging. A couple of years ago, I did a hands-on activity with middle-schoolers that covered molecular structure, of all things. It's based on a VSEPR demo using balloons. Blow up 4 standard balloons to a pretty big size, and tie them off. Now try to take the ends and tie them all together. You will notice when you do that that you get a tetrahedral arrangement. It is a great intro into 3D structure. Then if you pop one of the balloons, it is trigonal planar, and pop one more and they go linear. In principle, every student can do this activity.

    I coupled it with model kits. From there we gave everyone a model kit and showed how that leads to 3D shape of molecules. I focused on molecules that have descriptive names like housane and bowtieane, and even boat and chair conformations. We finished up by having the kids make and name their own molecules. Like dinosaurane, of course, but my favorite was keychainene, which was interlocking rings.

    It's fun because it's like playing with blocks (or erector sets), and, most importantly, it's SAFE

    1. You could also discuss why a balloon filled with helium floats and a balloon filled with air falls.

  8. I personally like the synthesis of iodoform - I use ethanol, iodine crystals, and sodium carbonate. I chose it for my students because it is literally the easiest organic reaction in the book. It's got a great element of suspense: the reaction mixture looks like crap up until all of a sudden the iodine clears and the canary yellow iodoform crystals start to precipitate out of solution. What's even better is that a simple test-tube decomposition of the product proves that it is a halocarbon - purple iodine vapor boils off, leaving carbon black behind. The only downside is that it smells like disinfectant - for obvious reasons - the classroom will retain that old-fashioned hospital smell for a few days, everybody in the building will know that you're doing o-chem.


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