How does temperature affect the growth of copper sulfate crystals?

Background Research A crystal is a clear, transparent mineral or glass resembling ice. It is a

very beautiful thing that many people admire daily. Many things affect the way a crystal grows but the one thing I am testing is temperature.

A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is crystallography. The process of crystal formation via mechanisms of crystal growth is called crystallization or solidification. (Campbell)

The word crystal is derived from the ancient Greek word “krustallos”, which had the same meaning, but according to the ancient understanding of crystal. At root it means anything congealed by freezing, such as ice. The word once referred particularly to quartz, or rock crystal.

The purpose of this experiment was to see if different temperatures affect the growth rate of crystals. I became interested in this idea because I saw a television show about crystals and wondered if temperature  affected the growth  rate of a crystal’s mass.

Hypothesis

• Temperature affects things in the world greatly. Everything around us is affected by temperature. The researcher wanted to know if the growth of crystals was affected by temperature. This would be measured using qualitative data . I hypothesize that the slower the crystals cool the larges the crystals will be, while the faster the crystals cool the smaller the crystals will be.

Experimental Design DiagramIndependent Variable:Temperature the crystals are grown in

Levels of IV

Cold temp (10 deg. C)

Med temp (20 deg C)

Hot temp (40 deg C)

Trials 3 3 3

Dependent variable: Growth of crystals.

Constants:Amount of sugarKind of soluteSame concentrationSame container

MATERIALS AND EQUIPMENT

•Water•Copper sulfate•Hot plate•Small glass beakers•Heat gloves•Latex gloves•Apron goggles•Funnel•Large beaker•Graduated cylinder

• Procedures: Preparing the solution:1. Measure 1000 mL of water into the beaker. Turn on the

warming tray and heat water until it begins to bubble slightly. Remove the beaker from the plate by using the tongs provided.

2. Add copper sulfate to the water using the metal holder. Add chemical to water until the solution is saturated.

3. Heat your solution again, until it begins to boil. Remove the beaker from the hot plate and try to add more chemical to the solution.

Prepare the small beakers by:1. Pouring the saturated liquid into the small beakers filling

them halfway.2. Place three beakers in the refrigerator (10 degrees

Celsius)3. Place three beakers on the counter at room temperature

(20 degrees Celsius)4. Place three beakers on a warming tray (40 degrees

Celsius)5. Let the crystals sit for a week at the end of the week you

will have to move the three beakers at 40 degrees Celsius to room temperature at 20 degrees Celsius.

 

Safety:

Wear goggles and aprons. Be careful when pouring hot liquids.

Data TableOn a scale from 1-10 , overall growth. (1 being low to no growth,10 high growth):

DV: Growth of Crystals

IV: Trial1

Trial 2 Trial 3 Mean

10 deg. C 4 3 4 3.67

20 deg. C 8 9 9 8.67

40 deg. C 6 6 9 7

Data Analysis

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Effect of temperature on growth of Copper Sul-fate crystals

10 deg. C20 deg. C40 deg. C

Different temperatures the crystals were grown in

Grow

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f cry

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of 1

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The crystals that were cooled at room temperature(20 deg. C) were larger than the others.

SETUP

Pictures taken by Student

MORE SETUP Pictures taken by student

COLLECTING THE CRYSTALS Pictures taken by student

50 DEGREES CELSIUS

20 DEGREES CELSIUS

10 DEGREES CELSIUS

Conclusion The purpose of this experiment was to see if the cooling rate of crystals effected the growth of them.

In the experiment the researcher found that the slower the cooling rate the larger the crystals. The differences were all ranked qualitatively. They were rated on a scale from one to ten based on overall mass, height, width, and depth. The mean of the 10 degrees Celsius group was 3.67. The mean of the 40 degrees Celsius group was 7. The mean of the room temperature group(20 degrees Celsius) was 8.67. The 10 degrees group had rankings of 4, 3, and 4 . The 40 degrees group had rankings of 6,6,and 9. The room temperature group(20 degrees) had rankings of 8,9, and 9. The range from the room temperature group to the 10 degrees Celsius group was 5. The room temperature group had the greatest ranking of crystals. The experiment could have been more accurate if there were more levels. A 30 degree Celsius group would have broken the distance between to 20 degree group and the 40 degree group . Also a gradual cooling rather than a quick shift of climate might have affected the results of the experiment. The data did support the hypothesis which was the slower the crystals cool the larges the crystals will be, while the faster the crystals cool the smaller the crystals will be.

When the crystals reach an equilibrium with a saturated solution, the free energy is more accepted by the molecules in the bulk of a crystal than on the surface. Bigger crystals have a slightly more free energy than small crystals because the fraction of surface molecules is smaller in bigger crystals. So, when crystals are in equilibrium with the surrounding solution, molecules are moving on and off crystal from and to the solution .Bigger crystals will grow over time at the expense of smaller crystals. This is true as long as they have time to equilibrate which is why cooling slower creates bigger crystals.

To study this further, the experimenter could conduct a study on whether crystals that are grown, melted, then re-grown are bigger than crystals that are only grown once. To see if the re-growing of crystals affect the size of them.

Works Cited "Crystals and Gemstones - Crystalinks." Crystalinks Metaphysical and

Science Website. Web. 03 Dec. 2009. <http://www.crystalinks.com/gemstones.html>.

"TPWD: Crystals -- Young Naturalist." Texas Parks & Wildlife Department | Welcome. Texas A&M University Press, 1983. Web. 02 Dec. 2009. <http://www.tpwd.state.tx.us/publications/nonpwdpubs/young_naturalist/earth_sciences/crystals/>.

"What is a Crystal? Crystals Defined." Chemistry and New Zealand. HA Campbell, 1998-2008. Web. 01 Dec. 2009. <http://www.chemistry.co.nz/crystals_defined.htm>.

"The importance of slow recrystallization." CU Boulder Organic Chemistry Undergraduate Courses. Web. 02 Dec. 2009. <http://orgchem.colorado.edu/hndbksupport/cryst/crystdiag.html>.

Von Bonsdorff-Nikander, Anna. "Optimizing the Crystal Size and Habit of." PharmSciTech: Home. 8 Sept. 2003. Web. 03 Dec. 2009. <http://www.aapspharmscitech.org/view.asp?art=pt040344&pdf=yes>.