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This is a nice little experiment for young scientists. We have used this one a
few times and has a pretty good wow factor. Note to macromolecular
crystallographers: Use this experiment along with pictures and stories about
macromolecular crystals to get a pretty good wow factor. For a bigger wow factor
throw in a picture of the space shuttle and talk about the microgravity protein
crystallization program.
Supplies:
600 grams (21 ounces) of sucrose (table sugar)
8 ounces of tap
water
a pot, beaker or saucepan to heat and mix the solution
a candy
thermometer (need to be able to measure 170°F)
a spoon for mixing the
solution
heat source (stove)
crystal growing container (glass or plastic
which can tolerate boiling water)
Caution! Since this experiment
involves heat, hot containers, and a hot sugar solution, there is the risk of
burns. Use extreme caution to protect yourself from burns. Children should be
supervised by an adult when performing this experiment because of the risk of
burns.
Procedure:
Place 600 grams (21 ounces) of sugar into
the pot for mixing and heating.
Pour 8 ounces (one cup) of water into the
pot containing the sugar.
Stir the sugar and water until all the sugar is
wet but not dissolved.
Heat the solution, stirring constantly. Place the
candy thermometer into the solution to measure the temperature of the solution.
Stir constantly until the solution is 170°F then remove the solution from the
heat.
Continue to stir the solution as the solution cools to
125°F.
Pour the 125°F (HOT!) solution into the crystal growing vessel.
Remember to use a vessel which will tolerate boiling water!
Allow the
solution to cool to room temperature. Close/seal the container.
Crystal
will grow in the container within 2 to 3 days. Maximum crystal growth will occur
by 7 days. One can grow more and larger crystals by allowing water to evaporate
from the solution (Crystallization by evaporation). Punch or cut holes in the
top of the container or simply leave the lid off the container. It may take many
weeks for the water to evaporate, therefore this method of crystal growth is
much slower.
Additional Notes:
Adding more sugar will
result in more crystals (likely smaller) and a more rapid appearance of the
crystals.
One can pour the sugar solution into 20 or 30 small containers
to share with an entire classroom.
Once can add a drop of food coloring
to the solution before crystals appear to grow colored crystals.
One can
perform a seeding experiment by doing the following: Soak a toothpick or other
small wood stick in water. Roll the toothpick in granulated sugar. Allow to dry.
Once the sugar solution is poured into the container and has cooled to room
temperature (see above) place the stick in the sugar solution. The granulated
sugar on the wooden stick will act as seed crystals. The seed crystals should
grow larger and one should see most of the crystal growth appearing on the
stick. This is how rock candy on a stick is made. One can also try this with a
thread or string to make rock candy on a rope! Once the crystals have stopped
growing, remove the stick or rope from the container and allow the crystal to
dry. Presto! Rock candy!
Additional
Information:
Sugar
The sugar used in this experiment is called
sucrose. Sucrose is made of three elements, carbon, hydrogen and oxygen. Sucrose
is sweet to the taste. Sucrose can be found in candy, soft drinks, jelly,
cereals, ice cream, gum and many other foods. It is estimated that in the United
States of America that more than 10 million tons of sugar are eaten each year!
Most sucrose comes from the farming of sugar beets and sugar cane. Sugar cane is
grown in Florida, Hawaii, Louisiana, and Texas. Sugar beets are grown in
California.
Rock Candy
Rock candy is one of the oldest forms of candy.
A long time ago, rock candy was used as a home remedy to treat certain
illnesses. Making rock candy is a difficult process and is often referred to as
an art since the trick is not only to grow sugar crystals, but BIG sugar
crystals.
Crystals
A crystal is a solid, but a very special solid
where the atoms are arranged in a very specific and organized geometric pattern.
A crystal is made of millions of atoms. These atoms, so small we cannot see them
even with a microscope, repeat themselves along three dimensions, eventually
making a crystal we can see with our eye.
Hampton Research, the company
hosting this page, helps people grow crystals of molecules much, much bigger
than sugar. These molecules are called biological macromolecules. Hampton
Research and many other scientists called Macromolecular Crystallographers grow
crystal of things called proteins, peptides, and nucleic acids. An example of a
protein would be a virus (AIDS Virus, Cold Virus), an antibody ( the bodies
defense against invaders such as viruses), amylase (converts pasta &
potatoes into energy, well sort of...), or collagen (the stuff that makes your
nose and ears stand up and out), and makes skin stretchy). An example of a
nucleic acid would be deoxyribonucleic acid (DNA - the chemical encyclopedia
that makes you what you are). An example of a peptide would be endothelin, a
molecule that controls your blood pressure.
Macromolecular
crystallographers grow crystals of these big molecules to make a blue print of
the shape of the molecule. The blue print can be used to study and better
understand the molecule. This goes along with the picture is worth a thousand
words concept. Pharmaceutical companies are using this technology to develop the
next generation of miracle medicines. Medicines that work better with fewer side
effects. Of course, crystallography can also be used for pretty ordinary (yet
amazing) stuff too. Stuff like Crisco (the greasy goop used for cooking and
baking) was developed using crystallography. And so was an enzyme used in
laundry detergent which gets the grass stains out of your clothes! (Thank
Procter & Gamble for these miracles)
Some crystallographers are
growing crystals in space on the NASA Space Shuttle. Scientists have found that
some crystal grow better and bigger in space compared to the same crystals grown
on Earth. Scientists are now studying why this is so, and how to take advantage
of the microgravity environment in space.
So while crystals are cool and
they are way fun, they are also very important to scientists, and to you too!
Did you know that crystals can be found in the following: Calculators,
computers, electronics, watches, telephones, and lasers? Did you know that
jewelry such as diamonds, rubies, emeralds and other gems are crystals?
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