Glacial Movement

I an currently teaching a geology lab for the first time, which has its challenges, but I since I have been rockhounding as a hobby for much of my life it has also been fun and educational.  I have been looking at older topograpic maps and aerial photos of various alpine glaciers and comparing them to more recent information and found that while some of the world's glaciers have advanced, many have been retreating. The picture shows an aerial photo of a Alaskan glacier taken in the 1950's in comparison to a more recent image on Google Earth. This is one of those glaciers in retreat.

Whak-A-Pack Valentines

Around this time of the year a local dollar store sells four Valentines Day-themed Wack-A-Packs for a dollar.  These are fun chemistry demos!  Inside each pack (bottom right in picture) is a deflated polyester balloon.  In the balloon is powdered citric acid and powdered sodium hydrogen carbonate (upper left in picture - much like an Alka-Seltzer tablet) and a pouch filled with water (lower left).  When the pack is struck hard, the water pouch breaks, enabling the water to dissolve the acid and salt.  These react to produce carbon dioxide gas which causes the balloon to inflate (upper right) and pop out of the pouch. I recommend passing the balloons around the classroom as soon as they open, because for a little while, the reaction can be heard fizzing in the balloons as carbon dioxide continues to be produced, and the balloon feels cold (I attribute this to the enthalpy of solvation of the sodium hydrogen carbonate).

Spontaneous Assembly (or "Self Assembly") of Hot Dog Slices and Meatballs

Originally posted May 22, 2012:

Cut hot dogs into ~1 cm thick slices and place them in a pan of water. They will float at the water's surface and attractive capillary interactions will draw them together into an organized close-packed array.

References:

Dungey, K. E. J. Chem. Educ. 2000, 77, 618.

Campbell, D. J.; Freidinger, E. R.; Hastings, J. M.; Querns, M. K. "Spontaneous Assembly of Soda Straws." J. Chem. Educ., 2002, 79, 201.

Campbell, D. J.; Freidinger, E. R.; Querns, M. K. "Spontaneous Assembly of Magnetic LEGO® Bricks." The Chemical Educator, 2001, 6, 321.

Campbell, D. J.; Freidinger, E. R.; Hastings, J. M.; Querns, M. K. "Spontaneous Assembly of LEGO®s." Chem13 News, Sept., 2001, 8.

ABOVE LEFT: Cutting hot dogs into slices. ABOVE RIGHT: Floating them in a pan of water. Note: sometimes tapping the pan will help shake out some of the defects in the assembled pattern.

Updated January 22, 2014:

BELOW: Assembly of meatballs after being churned about in boiling water.

A Redneck "Bleeper"?

It seems that when I fire a piezoelectric grill lighter near my TV tuner, it interferes with the picture a little and cuts out the sound for a about one syllable's length of time.  Another lighter on another tuner seems to just make a brief horizontal line on the screen but not so effective with cutting the sound.  Must be some radio-frequency emission in that electrical pulse? The effect happened on the 3 channels I tried. I do not really have a picture for that experiment, so I will use this pic of a fiery demo. The Bradley University Chemistry Club Demo Crew had their 120th show on Wednesday.  Thank God, we finally reached the 10,000 customer mark.  I was acting as the spotter as a student squirted water into burning liquid wax. If overdone, the flames could probably hit the lecture hall ceiling.  

"Yogurt Lab" (not a demo)

My family and I were in Minneapolis, MN, this past Friday, and while we were exploring the skyway we found a frozen yogurt place called "Yogurt Lab."  It's part of a chain in Minnesota, see: http://www.yogurtlabs.com/. We enjoyed the snack and I loved the decor, especially the lamps that looked (but happily did not smell) like triethylamine molecules.

Very hot water in very cold air

During the present cold snap that is gripping much of the nation (-8 F for a high here in Peoria today), the Internet and other media outlets have been describing what happens when you toss near-boiling water into the very cold air.  Basically, the hot water breaks into fine droplets which instantly freeze to make an ice cloud, see: http://www.huffingtonpost.com/2014/01/04/boiling-water-extreme-cold-water-gun-ice-crystals_n_4538522.html?utm_hp_ref=mostpopular for more explanation.  I tried it, too, with cold water as a control experiment (no "cloud" was produced).  CAUTION: I have heard that people are burning themselves with hot water!  The air is not cold enough to freeze all of the water.  Throw the water away from you and downwind!

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!