Test Tube Science:Dancing Raisin

   -One test tubes
   -One raisin
   -10 mL soda pop

For a gas to come out of a liquid it needs a nucleation site.  The raisin provides nucleation sites for the carbon dioxide in the soda pop.  The carbon dioxide sticks to the raisin surface until it is brought to the surface of the soda.  The bubbles pop and the raisin drops to the bottom and the process repeats.

Pour 10 mL soda into the test tube.  Now place the raisin into the soda.  Watch what happens.  What else can you get to dance (try a pea or peanut, bead or button)?  Does the time between rising and falling change over time?


Happy Birthday Louis Pasteur

Louis Pasteur was born today, December 27, in 1822. Pasteur's early work as a chemist resolved a problem concerning the nature of tartaric acid. A solution of this compound derived from living things (specifically, wine lees) rotated the plane of polarization of light passing through it. The mystery was that tartaric acid derived by chemical synthesis had no such effect, even though its reactions were identical and its elemental composition was the same.

Upon examination of the minuscule crystals of synthetic sodium ammonium tartrate, Pasteur noticed that the crystals came in two asymmetric forms that were mirror images of one another. Tediously sorting the crystals by hand gave two forms of the compound: solutions of one form rotated polarized light clockwise, while the other form rotated light counterclockwise. An equal mix of the two had no polarizing effect on light. Pasteur correctly deduced that the molecule in question was asymmetric and could exist in two different forms that resemble one another as would left- and right-hand gloves, and that the organic form of the compound consisted purely of the one type. This was the first demonstration of chiral molecules.


Happy Birthday Vladimir Markovnikov

Vladimir Markovnikov, born December 22, 1838, was a Russian scientist who stated with the addition of water to an alkene to form an alcohol, the hydroxyl group bonds to the carbon that has the greater number of carbon-carbon bonds, while the hydrogen bonds to the carbon on the other end of the double bond, the one that has more carbon-hydrogen bonds.