The Effect of Temperature and Type of Solute on Crystal Mass

Researched by Brooke S.
2003-04



PURPOSE

The first purpose of this experiment was to determine the mass of crystals grown from various solutes dissolved in water.

The second purpose of this experiment was to determine the mass of crystals grown at different temperatures.  

I became interested in this idea a few years ago when for my birthday my aunt bought me a crystal growing kit. I’ve been fascinated with their colors and how they grow.

The information gained from this experiment could help consumers and manufacturers. It would also be useful to those who make computer chips and people who make sugar.


HYPOTHESIS

My first hypothesis was that alum would grow the greatest mass of crystals.   I based this hypothesis on an article that I found in Britannica Intermediate Encyclopedia that said, “Alum works best…”.  

My second hypothesis was that for all of the various solutes, crystals would grow better in warmer temperatures than in colder temperatures.   I based my hypothesis on the book Crystals and Crystal Gardens you can Grow which said “Place the experiment in a sunny place. ” This made me think that it needs to be in a warm place.

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EXPERIMENT DESIGN

The constants in this study were:

  •  The mass of solute
  •  The volume of water
  •  Size of jar
  •  Amount of light
  •  Time to grow
  •  The procedure I used 
  •  Length of string
  •  Time observations are made
  •  Temperature of water for each group


The manipulated variable in the first phase of this experiment was the solutes.  
The manipulated variable in the second phase of this experiment was the different temperatures crystals were grown.

The responding variable in this experiment was the mass of the crystals grown.  

To measure the responding variable I used a triple beam balance calibrated in grams.

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MATERIALS


QUANTITY ITEM DESCRIPTION
1 Measuring Cup
16 Small plastic cups
16 #2 pencils
16 10 cm. Pieces of string
1 Refrigerator
1 Windowsill
750 ml. Sugar
750 ml. Epsom salt
750 ml. Table salt
750 ml. Alum
Triple Beam Balance
Medium Sauce Pan
Ruler
Pair of Scissors
Wooden Stirring Spoon
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PROCEDURES

  1. Make supersaturated solution of sugar
  2. Pour 500 ml. of water into a medium sauce pan, put it on a burner and turn it on high
  3. Wait until the water starts boiling then start adding spoonfuls of sugar. Keep track of how much you are putting in and stir until no more can dissolve 
  4. Turn off the burner and let the saturated solution of sugar sit until it’s cool. Then it will be supersaturated 
  5. Take 250 ml. of the supersaturated solution and pour it into one of the cups 
  6. Do step 2 three more times
  7. Next tape the 10 cm. pieces of string onto the middle of the #2 pencils
  8. Place one of the #2 pencils on top of each of the plastic cups letting the string hang into the supersaturated solution
  9. Put two of the cups in the refrigerator at about 3*C and two on a safe sunny windowsill at room temperature which is about 21*C
  10. Do steps 1-5 the same for Epsom Salt, Alum, and Table Salt except just pour in 750ml. of the solute right away and take it off the burner
  11. Check and see the growth of the crystals once every day and take observations on the growth
  12. Let them grow for two and a half weeks
  13. After they have grown for three weeks drain all the liquid in all the cups and take the pencils off the strings 
  14. Leave the strings inside the cups and put the cups on the triple beam balance one at a time 
  15. Record the weight 
  16. After you have weighed and record all of the cups weigh another cup with nothing in it 
  17. Subtract the weight of the cup off of the total amount for each cup

RESULTS

The original first purpose of this experiment was to determine the mass of crystals grown from various solutes dissolved in water.

The original second purpose of this experiment was to determine the mass of crystals grown at different temperatures.

The results of the experiment were that Epsom salt grew more crystals than alum. Also that almost all of the crystals grew better at 3*C than at 21*C.

See my table and graph below.


CONCLUSION

My first hypothesis was that alum would grow the greatest mass of crystals.

The results indicate that this hypothesis should be rejected because in both tests, the crystals grown at 3°C and the crystals grown at 21°C, Epsom salt weighed the most and made the most crystals, not the alum.  

My second hypothesis was that for all of the various solutes, crystals would grow better in warmer temperatures than in colder temperatures.

The results indicate that this hypothesis should be rejected because the average mass of the 3*C crystals was 69. 2 and the 21*C crystals was only 53. 2

Because of the results of this experiment, I wonder if different solutes would have similar results at other temperatures.

If I were to conduct this project again I would do more trials for each solute.
 
 

RESEARCH REPORT

Introduction
Crystals are useful and important in several ways. For most of recorded history crystals such as diamonds have been valued by society.   Today crystals are very important in the computer industry. Better understanding the process of crystallization is vital.

Crystals
What are Crystals?
Crystals are atoms placed in a regular pattern. The Greeks word for crystals was “krystallos”, which means both ice and quartz. They thought that quartz was ice that had become permanently solid. In today’s world a crystal is considered a solid object with flat surfaces meeting in straight lines and sharp corners. Diamonds, snow, and rock salt are the best-known crystals. In a crystal color can be its best feature, but in the daylight sometimes it will seem colorless. Almost all non-living things have crystals in them. Things like metals, rocks, snowflakes, salt, and sugar have crystals in them.

Crystals in the World
Crystals are almost everywhere because all rocks have crystals in them.   Crystals are very important to today’s technology and without them people couldn’t make computer chips. Crystalline rock makes mountains and ocean floors.

Classification
The first question asked about a crystal was “What is it” and to find out you have to test its properties. Crystals grow as atoms rearrange and it is very rare to find a perfect crystal. While a crystal is growing, in about one hour millions of atoms will move into place in the surface of the crystal.

Habits
The habits of a crystal are very important in crystallography and a habit also helps identification. The habits are so important that sometimes no other feature is necessary to look at. When they grow some of the sides develop more than others and it will create a whole different crystal shape. Most of the minerals come in groups of many crystals instead of single crystals and this is called aggregates.

Discovery
People have been searching for deposits such as metals and gems for a long time. There are large quantities of copper but silver, diamonds, and gold come in much smaller amounts and so the prices are much higher. Scientists have tried to make crystals for over a century. Synthetic crystals are made flawless unlike a real crystal and they are made for a specific size and shape. Since crystals are so important to modern technology they have to keep making crystals more efficiently.

Solutes

Alum
The chemical formula for common alum is K2SO4·Al2(SO4)3·24H2O.   Alum is formed when two single salts form with water into a double salt.   In common alum the single salts are potassium sulfate and aluminum sulfate.   Sometimes this is called potassium alum. It is used to help stop bleeding and shrink body tissues.  

Epsom Salt
Epsom salt is magnesium sulfate. Epsom salt was first found in Epsom, England that is why it’s called Epsom salt. Epsom Salt was used for a laxative a long time ago but now is hardly ever used.   It was also used for soaking inflamed body parts.

Salt
The chemical formula for salt or sodium chloride is NaCl. Salt has always been used for preserving and flavoring food. Now salt is used in chemical products and chemicals. Salt crystallizes in almost perfect cubes that are clear even though they can appear multiple colors. The United States of America and China are the highest rank of salt production.

Sugar
Sugar is used as a sweetener. Sugar is a carbohydrate and is used for mixing cement and making plastics. Since most medicines taste awful some have sugar in them to hide that. Bagasse is a material found in sugar when it has been removed from sugar cane. Bagasse is either made into wallboard or paper or turned into an energy source.   Monosaccharides and disaccharides are the two types of sugar. The simplest carbohydrates are monosaccharides and disaccharides have two monosaccharides.   Glucose and fructose are the two types of monosaccharides and sucrose and lactose are the two types of disaccharides.

Crystallization

What is Crystallization?
The study of crystallization is called crystallography. Crystallization is when substances turn into crystals. Crystallographers measure angles on crystals.

Summary
Crystals are both useful and important. Ever since the ancient Greeks, people have studied crystals. Crystals come in several types each with different properties. Better understanding of crystals will benefit the computer industry.

BIBLIOGRAPHY





“Crystals,” Britannica Intermediate Encyclopedia. 2003.

“Crystals,” ENCARTA Encyclopedia Deluxe, 2001.

Dazed. “Supersaturated Solution” December 3, 2003.
http://www. askjeeves. com/supersaturatedsolution

Stangl, Jean. “Crystals and Crystal Gardens you can Grow” New York: Franklin Watts 1990

Summons, William B. Jr. "Crystal," World Book Encyclopedia, 1999.

Symes, Dr. R. F. and Harding, Dr. R. R. “Crystal and Gems” New York: Alfred A. Knopf Inc. 1991

Vancleave, Janice.   “A+ Projects in Chemistry” New York: John Wiley & Sons, Inc.
 

ACKNOWLEDGEMENTS

 I would like to thank the following people for helping make my project possible:

  •  My mom for helping me pick a topic and helping get all of the materials for my experiment
  •  Mr. Newkirk for guiding me the whole way
  •  Mrs. Helms for answering all my questions
  •  My friends for being there for me and making sure I took a break once in a while

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