The purpose of this experiment was to determine which temperature (hot,
cold or room temperature) affects crystal growth rate the most.
I became interested in this idea because I've wondered about crystals
and crystal growth since I was little.
The information gained from this experiment may help other scientists
and people who study crystals and crystal growth. Also, it may help computer
chip manufacturers, as there are crystals in computer chips.
My hypothesis is that crystals will grow faster in hot temperature rather
than in room temperature or cold temperature.
I base my hypothesis on information from several books that suggest
growing the crystals in hot water for the best crystal size.
The constants in this study were:
The manipulated variable was the temperature of the crystal growth locations
(a hot, cold, or room temperature).
The same length of string
The same brand and amount of rock salt
Start growing the crystals at the same time
Same size of beakers for the crystals to grow in
Same amount of water
The responding variable was the growth rate of the crystals.
To determine the crystal growth rate, I defined the beaker with the
most crystal growth as 100%. If any beaker had no growth, that would be
called 0%. I estimated the percentage between 0% and 100% for all other
||Closet with a door
||Pieces of string
||Beakers (must hold more than 250 ml)
||Heating pad temperature water
||Refrigerator temperature water
| 250 ml
||Closet temperature water
||Heating pad (11" by 14")
1. Pour 250 ml of heating pad temperature water into 3 beakers
labeled 1,2 and 3, and place them on the heating pad, which should be on
high, for 10-15 minutes.
2. Do the same as #1, but pour closet temperature water into 3 beakers,
and put them in the closet for 10-15 minutes.
3. Do the same as #1 and #2, but pour refrigerator temperature water
into the remaining 3 beakers which should also be labeled 1,2 and 3 and
put them in the refrigerator for about 10-15 minutes.
4. While the water is adjusting to the temperature it should be, tie
1 piece of string to each pencil around the middle, and tie one paper clip
to the end of each piece of string. Repeat this same step until all the
string pieces are tied to each pencil and the paper clips are tied to the
5. When the water is ready, have 1 person go to each temperature of
water. (1 person at the refrigerator, 1 person at the heating pad, so on.)
Have all 3 people measure 2 tbsp. of rock salt into all 3 beakers, all
3 people measuring simultaneously.
6. Wait for about 3 days for the full growth.
7. Record all the data from the experiment.
The original purpose of this experiment was to determine which temperature
(warm, cold or room temperature) affects crystal growth rate the best.
The results of the experiment were that the hot temperature grew the
fastest, and the room temperature grew half as fast and the cold temperature
did not grow at all.
See the graph below.
My hypothesis was that the crystals would grow faster in a hot temperature
rather than a cold temperature or a room temperature.
The results indicate that this hypothesis should be accepted, because
my prediction was right, the hot temperature crystals did grow fastest.
Because of the results of this experiment, I wonder if I should have
waited 2 days to determine which grew the most. I also wonder if
the same thing would happen with sugar, epsom salts, or other types of
If I were to conduct this project again I would have run more trials
and would have used more substances (table salt, sugar or rock salt ).
I would also have measured the mass of the crystals rather than the time
it took them to grow.
Crystals are used for many reasons. Some people use them as healing
stones. They are also used in jewelry, such as diamonds. The Merriam-Webster's
Collegiate Dictionary defines a crystal as quartz that is either transparent
or nearly so and that is either colorless or slightly tinged.
Crystals form whenever a solid is formed from fluid. Crystals
form from vapors, solutions or molten materials, and are built from repeating
units. Crystals grow from the outside, salt crystals build up from sodium
and chloride ions. Crystal formation is called ëcrystallizationí.
Crystallization means "become crystals". Snowflakes form from water vapor.
Rocks are usually made up of 1 or more minerals. Most non-living substances
are made of crystals. If the cooling of obsidian is slower than usual,
a new rock is formed called felsite. Felsite is crystalline, and its crystals
cannot be seen with the naked eye.
Shapes and Kinds of Crystals
There are many different shapes and kinds of crystals. For starters
there are the shapes. There are about 22 crystal shapes. Some of them are
cubes, hexagonal and prisms. All crystals are not the same shapes. All
perfect crystals have flat surfaces.
There are also the kinds. For example, there is basalt, salt,
sand, quartz, granite, obsidian, shale, marble, slate, petrified wood,
diamonds, snowflakes, rhyolite and felsite, they are all crystals.
Basalt has crystals inside them. Quartz is the most common mineral,
and is also distributed all over the world. Rock quartz can only be melted
at a very high temperature. Granite is not similar in nature, or in other
words it is homogenous, and cannot be a single crystal. Obsidian
is a glassy, lava-made rock. Shale, marble, slate, granite and petrified
wood contain crystals that can be seen with a magnifying glass. Granite,
rhyolite and felsite are not similar in nature and cannot be single crystals
but are crystalline.
What is Salt?
Salt is a clear, brittle mineral that is used for flavoring food
and preserving food since ancient times. Salt is used in a manufacture
of a large number of chemicals. Salt consists of sodium and chlorine. Its
chemical name is ësodium chlorideí, and its mineral name is
ëhaliteí. Salt forms crystals that are almost perfect cubes.
Salt can be broken down to make a variety of sodium and chlorine products.
About 5% of the salt consumed in the U.S. today is used as a flavoring
for food. Seawater contains about 2.5% salt. Salts are among the most important
The Study of Crystals
The study of a crystalís growth, shape and geometric character
is called crystallography. A crystallographer is a scientist who studies
the atoms in crystals and crystals themselves. Crystallography is very
important in physics, physical chemistry and biochemistry.
'Crystal' comes from a Greek word meaning clear ice. In the
late sixteenth century, Andreas Libavius, made the theory which said, "Mineral
salts could be identified by studying the shapes of the crystal grains."
In 1669, Nicholas Steno observed that corresponding angles in 2 crystals
of the same material were always the same (1669). 'Krystallos' came from
Ancient Greek meaning ice and quartz. Ancient Greeks thought quartz was
another form of ice that was permanently solid. 'Amorphous' comes from
a Greek word meaning without form, but the English meaning is solids that
have no crystalline structure. 'Crystalline structure' means made up of
What's inside Crystals
Ions, atoms and molecules make up crystals. All matter on Earth
is made of atoms. Molecules in a crystal are held tightly together, but
they still vibrate because of thermal energy. Melting is a phase change.
Ice has heat energy.
In this report, there are facts about crystals. For example,
what's inside crystals, the study of crystals, crystal's history, formation
and shapes and kinds.
Burgess, Dr. Jeremy "Salt Crystals" Microsoft Encarta Deluxe 99,
"Crystals" Comptonís Interactive Encyclopedia, 1995
"Crystal (Mineral)" Microsoft Encarta Encyclopedia Deluxe 2000
"Crystal Structure and Crystallography" Comptonís Interactive
"Crystals" The World Book Encyclopedia of Science, vol. 2
Dean, Walter E., Jr. "Salt" The World Book Encyclopedia
1991 vol. 17 Pg. 72-73, 75
Holden, Alan "Crystal" Encyclopedia Americana, 1999 vol.
"Matter" Comptonís Interactive Encyclopedia, 1995
"Quartz" Microsoft Encarta Encyclopedia Deluxe 2000
Sander, Lenore, The Curious World of Crystals, New York, Prentice-Hall,
Schumann, Walter Rocks, Minerals and Gemstones Boston, New
York; Houghton Mifflin Company 1993
Simmons, Jr. William "Crystal" World Book Encyclopedia 1995
Stangl, Jean, Crystals, New York, London, Toronto, Sydney, Franklin
"What is a Crystal?" (Online) Available http://www.geology.wisc.edu/~jill/Lect4.html,
November 3, 1999
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