SCIENCE FAIR PROJECT
Changing The Freezing Point of Water
Corben Cardon| Mrs. Mcnees| Syracuse Jr. High
STATEMENT OF THE PROBLEM
• If I add salt or sugar to water, will it lower the freezing point of the
water.
RESEARCH
– The freezing point of water is 0˚ Celsuis, or 32˚ Fahrenheit.
– Salt and sugar molecules have more atoms of carbon, hydrogen, and sodium.
– A salt molecule forms a network of sodium and chlorine atoms.
– These atoms are linked together in very polar covalent bonds.
– A sugar molecule is made up of of of 12 atoms of carbon, 22 atoms of hydrogen, and 11 atoms of oxygen.
• http://www.exploratorium.edu/cooking/candy/sugar.html
http://answers.yahoo.com/question/index?qid=20081129155048AAxU9okd
http://chemistry.about.com/od/waterchemistry/f/freezing-point-of-water.htm
HYPOTHESIS
• If salt and sugar molecules have more atoms of carbon, hydrogen and
sodium, then the water will take longer to freeze, because there will
be more molecules to freeze.
PROCEDURE: MATERIALS
• Freezer
• Water
• Cups
• Salt
• sugar
PROCEDURE: STEPS
• Fill three cups of the same size with one cup of water.
• Add on tablespoon of salt to one cup, add one tablespoon of sugar to
another cup, leave one with just water.
• Put them in the freezer.
• Check every 30 minutes to see if frozen.
VARIABLES
• Constants: Temperature of freezer.
• Controlled variables: Water with salt or sugar added.
• Independent (manipulated) variable: Plain water.
• Dependent (measured) variable: Freezing point.
DATA/OBSERVATIONS
•
The cups were placed in the freezer at 5:30.
•
5:35, All three cups were still completely ligquid.
•
5:40, Still liquid.
•
6:00, Still liquid.
•
7:00 , The plain water is starting to freeze on the top. The other 2 cups are still liquid.
•
7:30, Saltwater: Liquid, Sugarwater: slush forming on top, plain water: starting to harden on the top.
•
8:00, Little (if any) change has occurred.
•
8:30, All three cups are frozen on top, the plain water has the thickest ice on top.
•
9:00, Slush on the saltwater, ice forming on sugarwater, plain water freezing through.
•
9:30, The saltwater is soft slush, the sugarwater is harder slush, the plain water is frozen solid.
•
10:00, Same.
•
10:30, The saltwater slush is hardening, the sugarwater is almost solid. The plain water is frozen solid.
•
11:30, The saltwater is almost frozen solid, the sugarwater and water are frozen solid.
•
12:00, All cups are frozen.
The plain water froze first, the sugarwater second, then the saltwater last.
CONCLUSION
Problem: Yes, adding salt or sugar to water will lower the freezing point.
Hypothesis: Supported. Conclusion:
Problem: Yes, adding salt or sugar to water will lower the freezing point.
Hypothesis: Supported.