Which Temperature Affects Crystal Growth the Most?

Researched by Kaitlyn S. 
1999-2000

Purpose

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. 


Hypothesis

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. 


Experimental Design

The constants in this study were:

    •  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 manipulated variable was the temperature of the crystal growth locations (a hot, cold, or room temperature).

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 beakers.
 



Materials

QUANTITY ITEM DESCRIPTION
1 Refrigerator
1 Closet with a door
9 Stirring spoons
9 (10-inch) Pieces of string
9 Beakers (must hold more than 250 ml)
2 tbsp. Rock salt
9 (medium-sized) Paper clips
250 ml Heating pad temperature water
250 ml Refrigerator temperature water
 250 ml Closet temperature water
1 Heating pad (11" by 14")
9 (5-inch) Pencils



Procedures

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 string. 
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. 



Results

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.
 


Conclusion

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 crystals. 

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. 


Research Report

Introduction
 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. 

Crystal Formation
 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 chemicals. 

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. 

History
  '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 crystals.

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.

Summary
 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. 


Bibliography

Burgess, Dr. Jeremy  "Salt Crystals" Microsoft Encarta Deluxe 99, 1999

"Crystals"  Comptonís Interactive Encyclopedia,  1995

"Crystal (Mineral)" Microsoft Encarta Encyclopedia Deluxe 2000

"Crystal Structure and Crystallography"  Comptonís Interactive Encyclopedia  1995

"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. 8

"Matter"  Comptonís Interactive Encyclopedia,  1995

"Quartz" Microsoft Encarta Encyclopedia Deluxe 2000

Sander, Lenore, The Curious World of Crystals, New York, Prentice-Hall, Inc., 1964

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 Watts, 1990

"What is a Crystal?"  (Online) Available http://www.geology.wisc.edu/~jill/Lect4.html, November 3, 1999 
 
 
 


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