Liquid Nitrogen Marshmallows

This evening I brought home a little liquid nitrogen and we added marshmallows that were cut into quarters.  The marshmallows soak up a little liquid nitrogen and become crunchy, almost like the marshmallows you find in cereal.  When you bite into the marshmallows, their coldness causes the moisture in your breath to condense and produce the appearance of steam as you chew them.  No need to use a full-sized marshmallow or just liquid nitrogen itself.  Too much cold shock to the mouth could crack a tooth.

Collecting Sap to Make Maple Syrup

Original post 3-20-14: The sap is running in our maple trees and I am collecting some to try to make maple syrup.  What an interesting exercise in working with colligative properties like boiling point elevation! I tried boiling down a little sap several years ago, but overshot the syrup stage to produce sugar.  To collect the sap, I drilled a hole in each tree to a depth of about 5-7 centimeters and angling somewhat upward into the tree.  For each spile, I used a (clean) plastic syringe and removed the plunger.  I cut the tip end off of the barrel with a razor blade, and then cut a sort of slit in the side of the barrel from the cut end until maybe a centimeter from the finger flange.  I inserted these spiles into the holes in the tree until only about a centimeter was showing (if you push too hard you might break the spile).  I oriented the finger flanges of each spile in a vertical position, which I used to wire on a one-gallon freezer bag with a zipper.  New post 4-13-14: I collected over 2 liters of sap (represented by the pitcher of water), which I boiled down to make about 100 mL of yummy maple syrup.  The whole process was fun, but it strikes me as quite energy intensive.

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.