Racquetball Modified to Jingle Bell using Liquid Nitrogen

A racquetball can be modified to ring like a jingle bell when chilled with liquid nitrogen.  First, attach a wire or string to the ball.  Next, cut an "X" into the ball and insert a glass marble into the ball.  At room temperature, the rubber is flexible and the jingle bell ball does not ring.  When the ball is cooled to liquid nitrogen temperature, the rubber cools to a glassy material (polymer chain mobility is decreased) and the jingle bell ball rings.  A movie of the demo has been posted to YouTube: https://www.youtube.com/watch?v=xfIm29nNo8g.  Happy Holidays!

Hoarfrost crystals

I like how these ice crystals on my car this morning had symmetry resembling full hexagonal or truncated snowflakes.

Comments on Tangle Proteins Building Set

I recently purchased a Tangle Proteins Building Set from Educational Innovations and just put together the first model in the set: the third IgG-binding domain from Streptococcal Protein G.  The pieces in the primary chain were hard to wrestle together. My assembly tactics ranged from dish soap to sandpaper to leather gloves to simple "elbow grease",  and the pieces eventually came together.  The clear lengths of plastic used to make hydrogen bonds should have probably been just a smidge longer.  The directions in the book had issues, too.  It was difficult to tell from the photographs where one structural element ended and the other began.  I have experienced similar difficulties in displaying the seams between LEGO bricks on my Exploring the Nanoworld with LEGO Bricks website (they are also brightly colored plastic pieces).  On the LEGO site, we have had to sometimes color the seams between the bricks with permanent markers to emphasize them.  The  first model also has an error in the instructions: only 12 red helix pieces were given in the list for the primary sequence, yet everywhere else in the instructions 14 red pieces are required.  Despite all these challenges, I think this little protein model is pretty cool when finally assembled. It features an alpha helix and a beta pleated sheet, and this inorganic materials chemist can appreciate the fact that, as others have said, the hydrogen bonds and other secondary interactions between various parts of the primary chain  really direct the structure of the entire molecule.  Two other models are also described, but this inorganic materials chemist would love to eventually see some metal binding sites (e.g. a heme group) added.

Elephant's Toothpaste in a Pumpkin (catalytic decompostion of hydrogen peroxide within dishsoap creates a foam)

ORIGINALLY POSTED 5-1-12:

Doing the "Elephant's Toothpaste" reaction inside a carved pumpkin (a plastic pumpkin works too). The foam oozes from the mouth and eye holes of the pumpkin, resulting in a totally gross demonstration! ABOVE: The foam is just beginning to ooze out. BELOW: At the end of the demo (left) and photographs of another run (middle and right). Aqueous potassium iodide was used as the catalyst. Special thanks to Kathleen Shanks from the Institute for Chemical Education for helpful advice.

This demonstration is based on an article published in Chem 13 News. We do not have the article information, but we would be happy to post it if anyone finds the reference.

UPDATE 11-18-13:

Here is a picture of the pumpkin that we have used for years of shows.  We tell the audience that the pumpkin is green because it does not feel very well.  The lid has been recently redesigned: 1) it is clear so that the demonstrator can monitor the initial progress of the reaction, and 2) the "stem" of the pumpkin is a wooden dowel that is long enough for the demonstrator to use to hold the lid down without discomfort from the exothermic reaction.  

Diffraction "rainbows"

At the church I attend there are some window decorations that are essentially diffraction gratings oriented in a variety of different directions.  When the morning sun shines through the gratings, an arc of colored lines appear on the opposite wall (top).  Now real rainbows (bottom) are a refraction phenomenon, not diffraction, but the resulting color pattern is the same, plus it is a good illustration of the impact of wavelength on diffraction patterns.

Gas Laws in a Microwaved Plastic Container

I have seen demonstrations of atmospheric pressure and the gas laws performed by first heating water inside a container (like a solvent can or an aluminum can), and then closing the container and allowing it to cool.  As the vapors inside the cooling container cool and condense, the pressure inside of the container decreases relative to the surrounding atmosphere and the container collapses.  Instead of these metal containers, one could also simply heat a water source like food inside a plastic container in a microwave oven while the lid is placed loosely on the container. As the contents of the container start to cool, the lid can accidentally seal onto the container, and the plastic container contracts.   This is a phenomenon many people have observed, lending itself to discussions of gas properties.

Photobleaching Construction Paper with Fluorescent Lights

I took down an old Bradley University Chemistry Club bulletin board and was impressed how, over the course of years, light from the fluorescent lights in the hallway in Olin Hall had penetrated thin copy paper (upper sheet in picture) and bleached the underlying construction paper from blue to gray (lower sheet in picture).  I was also impressed how ink on the paper had slowed that process sufficiently that the printed ink on the copy paper left an image on the construction paper.

Armored Mud Ball

I just learned over the last year what armored mud balls were (balls of mud that are rolled by moving water over stones, which stick to the surfaces of the balls) and how they have been found associated with the Kankakee torrent here in Illinois: http://books.google.com/books?id=cPfw7aIlowIC&pg=PA158&lpg=PA158&dq=armored+mud+ball+kankakee+torrent&source=bl&ots=Rp44nRB-4p&sig=8cV05df3PEM_MenwDzPRPgllykA&hl=en&sa=X&ei=a4URUpbsGaWIyAH9v4HICw&ved=0CC0Q6AEwAA#v=onepage&q=armored%20mud%20ball%20kankakee%20torrent&f=false.

I was surprised to find an armored mud ball, presumably recently made, in a creek bed in Bartonville where I was fossil hunting.  I saw a recipe for making a food analogy of the mud balls that was published by the National Park Service: http://www.nps.gov/badl/forkids/upload/Make%20an%20Armored%20Mud%20Ball.pdf.  I am reminded of yummy nut-covered fudge balls that I have eaten around Christmastime.

Measuring Magnetic Properties of Materials (Including Your Hand) with an Electronic Balance

featuring contributions from Paul Lee and John Tian

All materials display some magnetic properties depending on such factors as their electron arrangement, temperature, and particle size/orientation. Three notable types of magnetism displayed in matter are diamagnetism, paramagnetism, and ferromagnetism. Diamagnetic materials have orbitals containing only paired electrons; each occupied orbital contains two electrons in opposing spin states. They tend to be nonmagnetic or slightly repelled by magnetic fields. Paramagnetic materials have some orbitals with unpaired electrons, each containing only a single electron with a single spin state. These materials are attracted to magnetic fields, but their random unpaired spin orientations only enable weak attractions.  Ferromagnetic materials have unpaired electrons similar to paramagnetic materials. However, the unpaired electron spins of the ferromagnetic materials are aligned cooperatively in magnetic domains, which enable much stronger attraction to a magnetic field than in simple paramagnetic materials.

It is possible to measure the relative strengths of magnetic properties in materials with simply an electronic balance (that should have draft doors and measure to tenths of milligrams), a strong magnet (preferably a neodymium-iron-boron magnet), and two polystyrene foam cups. This demonstration is based on that described in Ellis, A. B.; Geselbracht, M. J.; Johnson, B. J.; Lisensky; G. C.; Robinson, W. R. Teaching General Chemistry: A Materials Science Companion; American Chemical Society: Washington, DC, 1993.

First, level the balance in a stable area, with few outside forces that can disrupt the balance. Next, place both cups on the balance pan with both openings facing each other forming a diamond-like structure. Place the magnet on top of the cups to isolate it magnetically from the balance mechanism.  The top of the magnet should be only a millimeter or two under the top draft door. Cut the cups smaller if the apparatus does not fit within the draft doors of the balance. Finally, with all draft doors closed, tare the balance to cancel out the mass of the cups and magnet. To measure the magnetic behavior of substances, place samples on top of the top draft door.  Paramagnetic and ferromagnetic substances will attract the strong magnet upward away from the balance pan, resulting in a negative reading on the balance display.  Diamagnetic substances will repel the strong magnet toward the balance pan, resulting in a positive reading on the balance display. It was amazing to us when we observed that even a hand held over the draft door over the magnet without touching the door will cause a slight positive reading on the balance display! We presume that water and other diamagnetic substances in human hands act to slightly repel the magnet.

Chlorophyll fluorescence from a violet laser pointer (updated)

A friend with a 405 nm laser pointer noted that if it is pointed at some plant matter like a spinach leaf then there is a reddish fluorescence (that can be a challenge to photograph).  Algae-laden water probably works best for showing this.  I'm guessing it is from the chlorophyll (see Figure 3 in http://icecube.berkeley.edu/~bramall/work/astrobiology/fluorescence.htm). NASA is using the fluorescent activity of chlorophyll to map photosynthesis on the Earth, see: http://www.space.com/22111-satellites-capture-photosynthesis-in-action-video.html

Estimating the Pressure Required to "Pop" a Film Canister Popper

Featuring contributions from Paul Lee and John Tian.

Boyle’s law states that the volume of a gas is inversely proportional to its pressure (assuming constant temperature and moles of gas). This demonstration uses this principle to create a powerful launch of a film canister top. NOTE:  Wear eye protection and enlist adult supervision for this demonstration!

Materials:

- Luer-lock plastic syringe with at least 60 mL capacity

- film canisters used for Alks-Seltzer popper demonstrations (white Fuji film canisters work best, ours was measured to have a 39 mL capacity)

- Luer lock syringe needle (we used 12 gauge)

- hot glue and glue gun

Preparation: 

1. Poke a small hole with the needle, preferably no wider than the diameter of the needle, in the bottom of the film canister. Be careful not to poke yourself! Remove the needle, cut and discard the sharp end of the needle off with a wire cutter, and replace in the canister.
2. Glue the needle firmly in the place with hot glue gun. Make sure to glue both the inside and the outside of the canister to keep the needle firmly in place. Make sure not to plug the hole of the needle with glue.
3. After the glue has cooled, attach the syringe to the needle using the Luer lock.
4. Carefully place the cap on the film canister without bending or twisting the needle in the canister. 

Demonstration:

1. Remove the cap from the canister.
2. Pull the syringe back to 60 mL.
3. Carefully place the cap back on the canister.
4. Aim the apparatus at a target away from people (e.g. the ceiling).
5. Pop the film canister cap by rapidly pushing in the syringe plunger as far as it goes.
6. If the "pop" does not work, go back to step 1.
7. Retrieve cap. 

The film canister cap flies off the film canister because of the buildup in gas pressure during a rapid decrease in volume. In our hands, 60 mL of air was added to a 39 mL canister to produce a powerful pop. Therefore, the pressure inside the canister would have built up from about 1.0 atm to about 2.5 atm. Pictures of the apparatus are shown below.

A Vinegar/Baking Soda Baster Blaster

Featuring contributions from Giuliana Bailey, Paul Lee, John Tian

The reaction of baking soda and vinegar is a familiar one for many science students; the formation of carbon dioxide gas as a byproduct is often used to create a “volcano” or “rocket” effect. This demonstration uses the buildup of pressure from the formation of the carbon dioxide gas in a water bottle to propel a turkey baster into the air. The baster tube should have a round cross-section in order to effectively fit the bottle opening, and we recommend that the rubber bulb be fastened to the tube with electrical tape.  To perform the demonstration, add about 16 g of baking soda to an empty 500 mL water bottle.  It is not necessary to clear the baking soda powder away from the hole in the bottle  Use the baster to draw up about 40 mL of vinegar.  Quickly place the point of the baster with vinegar into the bottle with baking soda.  The baster tip should seal into the bottle but not fit so tightly that the baster cannot move.  Squeeze the vinegar into the bottle, and, making sure that the bottle and baster are still standing upright, release your grip on the baster bulb.  Within seconds, the carbon dioxide produced by the reaction will propel the baster into the air.

Sorry, some sort of error is turning my pictures sideways!

Seltzer Popper Launches Glow Stick

I discussed in previous blog entries how pressure from chemical production of carbon dioxide can be used as the basis for propulsion. The carbon dioxide can be produced by reaction between acids and carbonate salts. The picture below shows a rocket based on the popular demonstration involving water and AlkaSeltzer® in a 35 mm film canister placed on a chassis made from LEGO® parts. The "fuel" for the popping canister demonstration is approximately half an AlkaSeltzer® tablet, which is placed into a 35 mm film canister (Fuji-brand film canisters seem to work best). Water is added to the canister (to fill it approximately one third to one half full) and then the canister is capped. Ordinarily, in demonstrating these sorts of poppers the canister is placed upright, but in this case the canister is placed upside down and a bit of poster putty is used to hold a glow stick upright on the canister.  The force of the popper explosion is sufficient to launch the glow stick a few feet into the air. ABOVE: The glowing popper rocket assembly. BELOW: Launch of a blue glow stick popper rocket.  The orange glow stick popper rocket has not launched.

Igniting an LED-containing Balloon

I purchased a few LED-light containing balloons last night at Wal-Mart to fill with hydrogen and explode.  The thought is that the LED light would make the balloon out of the ordinary, maybe producing a line like "Hmmm...this balloon seems to have a warning light in it..."  I turned on the light in one of the balloons (it was dimmer than I would have liked) and filled it with hydrogen gas.  Tonight after dark I set it off with a candle on my back porch - still shots from a movie are shown below.

The LED light was tossed a couple feet but otherwise seemed unharmed - I opened it up and put a piece of plastic between the batteries to try to reuse later.  The balloon explosion seemed to have a few more sparks than usual - not sure why.  I'm also not sure what a more intense hydrogen-oxygen explosion would do to the LED and the batteries.

Bad Elements on Notebook Cover

A friend (Brittany Trang) found this notebook cover.  Seems like the goal is to make science somewhat appealing to girls (which is good) but the elements symbols are messed up (which is bad).  It's even sadder to think that it could have been done using boron (B), radium (Ra), indium (In), and yttrium (Y).

End of Demo Crew Season 4

Last Friday the Bradley University Demo Crew (a part of the Bradley University Undergraduate Chapter of the American Chemical Society) did its last event of the academic year. We reached out to about 2375 participants over the course of 25 events (these numbers are new seasonal highs for us) utilizing the assistance of 34 students (one did 13 events) and other faculty members.  Our grand total over the four years of the Demo Crew project exceeds 100 events and 8800 participants - we hope to exceed the 10,000 mark next year.  We are grateful for support, including from the Bradley University Mund-Lagowski Department of Chemistry and Biochemistry, the Illinois Heartland Section of the American Chemical Society, and the Illinois Space Grant Institute. If you have suggestions for more funding sources for this sort of thing let me know. One of the attached pictures shows what my backyard looked like after hosing off and hanging all of those green tarps from last week's shows.

Planet gravity bottles at the Challenger Learning Center

Earlier this week, one of my classes visited the Challenger Learning Center at Heartland Community College in Normal, IL.  As noted on their website (http://challengerlearningcenter.com/):  

“The Challenger Learning Center provides simulated space missions to central Illinois schools of K-12 students. Kindergarten through fourth grade students take on the roles of astronauts, scientists, and engineers during their MICRONAUT mission. Students in grades fifth through eighth become the flight controllers and astronauts during their SCHOOL mission to Rendezvous with a Comet, or take a Voyage to Mars. Ninth through twelfth grade students not only become the flight controllers and astronauts during their HIGH SCHOOL mission, but also lead their mission, Operation: Planet Rescue.”  The place is pretty awesome, though the cost of the missions might require some creative funding on the part of schools.  Since we were a group of teachers, we got a free tour after hours (though we did not run any missions).  One demo that a lot of us liked were 20 oz. Pepsi bottles that were emptied, refilled with sand and metal shot to alter their weights, and then relabeled to explain what the weights of the bottles would be on various planets.  These were developed by the director of the center.

Ammonium nitrate in the news and over the years

Ammonium nitrate finds its way into any good discussion of nitrogen chemistry.  This compound, used as a fertilizer in many cases, also can be used as an explosive.  A former student of mine had a parent that worked at a company that mixed ammonium nitrate and oil to produce a blasting material for construction purposes. The oil adds more reducing power to the redox reactions involved in the explosions, increasing their potency. Unfortunately, many terrorists have produced a similar mixture and used it in events such as the World Trade Center bombing in 1993 and the Alfred P. Murrah federal building bombing in Oklahoma City in 1995.  Ammonium nitrate can explode to do plenty of damage without oil, too.  One example is the  explosion at the fertilizer plant in West, TX (which is located in the eastern half of Texas), see:  http://www.cnn.com/2013/04/19/us/texas-explosion/index.html?hpt=hp_inthenews.  Previous to that there was an explosion at a fertilizer plant in France in 2001.  And of course there is the Texas City disaster in 1947, in which two ships loaded with ammonium nitrate exploded and did extensive damage.  I visited Texas City in 2011 and stopped by their city museum and other sites.  They featured, among other exhibits, information about the disaster.  Some pictures of that visit are featured in this post.

Heterogeneous Catalysis with the AOSept System

I wanted a small demo of heterogeneous catalysis for class today, and found a package featuring the AOSept contact lens cleaning system in my demo area.   In this system,

the contact lenses are placed in a cleaning solution that contains hydrogen peroxide.  To help keep the peroxide from getting into person's eyes, the vial containing the peroxide solution and the contact lenses also contains a platinum-coated disk, which catalytically decomposes the hydrogen peroxide into oxygen gas and water.  After about 6 hours, the contacts are clean and the peroxide has decomposed.  The picture shows oxygen bubbles in the vial that I passed around my class.  It should be noted that there is a gas vent in the top of the vial and therefore the vial should be kept upright to prevent spills.

Space Shuttle Tile

Years ago, NASA gave away space shuttle tiles to educational institutions for demonstration purposes. One thing that amazed me when I first picked one up is how lightweight

it was - but I guess that makes sense if they needed to be launched into space. We still use them as props at outreach events.  I have included an optical micrograph of the glass fibers in the tile structure.  The black marks at the bottom of the picture are one millimeter apart.

Elastic Strip (Rubber Band or Balloon) Thermodynamics

Some elastic polymers heat up when they are stretched (and cool down again when they are allowed to relax back to their original position).  These temperature changes can be demonstrated by stretching thin polymer strips such as rubber bands, deflated balloons and even plastic grocery bags.  These temperature changes can be detected with thermometers that can monitor the temperature of surfaces or by placing the polymer strip against your upper lip - a temperature-sensitive body part.

The origin of this thermal behavior lies within the attractions between the chainlike molecules of the polymer.  In an unstretched polymer, the molecular chains are tangled like a plate of spaghetti.  In this tangled arrangement the molecules do have optimum contact (or optimum attraction) between the chains.  When the polymer is stretched, the molecular chains are pulled into alignment in the direction of stretching and have greater contact (and greater attraction) with each other.   When attractive forces are satisfied, energy is released.  In this case the energy is released in the form of heat.  When the polymer is released and the chains move back to their original position against their attractive forces, energy is consumed and the polymer cools down.

This polymer strip behavior can also be explained using more in-depth thermodynamic concepts such as enthalpy (H), temperature (T), entropy (S), and Gibbs free energy (G).  These concepts can be connected by the mathematical relationship that states that the change in Gibbs energy (G) for a process is equal to its change in enthalpy (H) minus the absolute temperature (T) multiplied by the change in entropy (S).  Stretching the strip is nonspontaneous, with a positive value of for its change in free energy, and its change in enthalpy must be negative, since the strip heats up and indicates an exothermic process.  Mathematically, its change in entropy must be negative.  This happens because as the strip is stretched and the molecular chains are pulled into alignment, the disorder within the plastic strip decreases.  Releasing the strip and allowing it to contract to its original shape is spontaneous with a negative change in free energy, and the change in enthalpy must be positive, since the strip cools down as it contracts.  Therefore the change in entropy must be positive.  This happens because as the strip relaxes and the molecular chains are moved out of alignment, the disorder within the elastic strip increases.

The pictures show a non-contact thermometer measuring the temperature of a relaxed and stretched deflated balloon.  Sorry about the rotated picture - there is a glitch in my software.