Date: Thu, 10 Dec 1998 21:53:16 -1000
From: Gail Peiterson <peite@punahou.edu>
To: Pinhole Listserv <pinhole@exploratorium.edu>
Subject: (no subject)
Aloha from Hawaii
This is a repeat of posting that I sent last year but figured
a. if you're like me you may have "filed" it too well
b. there are new folks on the list
c. I should be doing a million other things but this was the best
alternative to the things I should be doing
d. The recent power outage ate your lesson plans
My holiday favorite "chemically correct" candy canes.
A Christmas Chemistry Experiment
Purpose: To observe the effect of temperature and torsion on the visible
configuration of certain groups of molecules.
Apparatus: 600 ml beaker, graduated cylinder, Bunsen burner (with ring
stand & ring & wire gauze), or hot plate, stirring rod, 150oC, thin
sheets of elemental aluminum, paraffin coated paper, newspaper to cover
work area. *This should be new equipment or substitute kitchen equipment
of comparable measurements, do NOT use previously used lab equipment for
this lab.
Chemicals/solutions: sucrose (s), concentrated glucose solution (l),
water, potassium hydrogen tartrate (s), extract from peppermint plant
(l), hydrated vegetable oil, consumable color altering solution
Procedure:
1. Using a 600 ml beaker and a stirring rod, thoroughly mix 225 g of
sucrose, 75 ml of concentrated glucose solution, 75 ml of water, and 1 g
potassium hydrogen tartrate.
2. When a uniform heterogeneous mixture is achieved, subject the
mixture to intense heat from the nearest source of burning methane. (Or
hot plate if no burning methane available.) continue to boil the
mixture, distributing the heat application evenly. During this
operation, avoid stirring because any external agitation will be
detrimental to the desired effect.
3. The viscosity is directly proportional to the quantity of heat.
This is an important factor in determining the end product of the
reaction. When the thermometer reaches 132oC, a sufficient quantity of
heat has been added. Extinguish the burning methane or stop the flow of
electrons to the hot plate.
4. Add extract of the peppermint plant, approximately 2 ml, and stir.
Pour one half of the mixture on a thin layer of elemental aluminum which
has been lubricated with the hydrogenated vegetable oil. To the portion
remaining in the beaker, add 1 ml consumable color altering solution and
then pour the mixture onto another piece of lubricated paraffin coated
paper. Also by friction, convert from solid to liquid some of the
hydrogenated vegetable oil in the palms of your hands.
5. When the mixture has cooled, work it to counter tensile strength of
both portions. Continue to stretch until the honey colored portion
becomes white. Divide each color into four segments approximately 20 cm
each. When ready combine one segment of each color. Do so with
torsion. Place the distorted object on a clean section of the
lubricated elemental aluminum sheet and shape in the form of a J tube.
Allow this remain undisturbed until the viscous J tube becomes rigid in
this position. Clean up all supplies and the work area while this
occurs.
Conclusion: This experiment may be summarized by the critical analysis
of the following question: How do your results compare with the
commercial product of the same species?
This experiment is fun to do but requires setting aside a set of
glassware just for food labs or going to your local thrift shop for used
glass measuring cups in metric (cover other side with tape)
and old glass corning ware pots etc. instead of beakers. The only
thing I had to buy new were candy thermometers. It is possible. This
recipe makes 4 good size candy canes but you can also clip the 4 canes
into bite sizes pieces for the entire class with a good pair of kitchen
scissors lubricated with margarine. Then each kid gets a sample & the
cost is less. Hope you have time to try this before the holidays.
Wishing you all a happy and healthy new year,
Gail Peiterson
Punahou School
Honolulu, Hi