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Surface Tension. Challenge to Excellence 2009 Science Fair. Big Question. What is the Surface Tension of Water? I chose this experiment because I was curious of what the surface tension of water was with different solutions. Hypothesis.
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Surface Tension Challenge to Excellence 2009 Science Fair
Big Question • What is the Surface Tension of Water? • I chose this experiment because I was curious of what the surface tension of water was with different solutions.
Hypothesis • I think the surface tension of water will be less with soap in the water. • I think this because when the smaller bubbles pop, they’ll pop the big bubble.
Interesting facts • With salt in the water, the surface tension is much higher. • With soap in the water, the surface tension was much less. • The tails side of the penny had a lower surface tension when tested.
Experiment-Materials • Penny • Water • Eye dropper • Salt • Liquid dishwashing detergent • Clean glass jars • Pencil and paper • Towel
Take the eye dropper with plain water and drop water on the heads side of the penny. Count the number of drops until it popped. (Don’t count the drop that popped the bubble of water.) Repeat steps one and two 4 more times. Record data after each test. Then repeat steps one, two and three on the tails side of the penny. Add 1 teaspoon of salt to 100 mL of water. Test solution 5 times on the heads side of the penny. Test same solution 5 times on the tails side of the penny. Record data after each test. Take new water and mix in 1 drop of dishwashing detergent into 500 mL of water. Test that solution 5 times on the heads side of the penny, and 5 times on the tails side of the penny. Record data after each test. Experiment-Steps
Control Group My control group would be my plain water solution. Variables My variables would be my saltwater solution, and my soap-water solution. Experiment-Control/Variables
Observations • The soap-water seemed to have thinned out. • The saltwater had a very high surface tension. • The plain water had a higher surface tension than I thought. • The soap-water solution had a lower surface tension that I thought.
Analysis of Data • Yes my experiment did test my hypothesis . • I know because I tested the surface tension of water with three solutions; plain water, water with salt, and water with soap.
Conclusion • Yes my hypothesis was correct. The only things I would change would to be to use a bigger coin, and to use more solutions. New questions: Why was the surface tension so high with the saltwater solution? What is the surface tension of other liquids?
References • http://www.sciencebuddies.org/science-fair-projects/project_ideas/Chem_p021.shtml • http://hyperphysics.phy-astr.gsu.edu/hbase/surten.html • http://www.ksvinc.com/surface_tension1.htm • http://en.wikipedia.org/wiki/Surface_tension