SURFACE TENSION
Tyler Davis | Mrs. McNees | Syracuse Jr. High School
Statement of the Problem
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How can the surface tension of water be changed
or weakened by adding different substances or
compounds to the water?
Research
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Summarize:
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When dealing with surface tension it is like a layer of skin.
Different liquids have different surface tensions.
The oxygen atoms tend to hold on the shared electrons from the
hydrogen atoms more tightly.
Hydrogen bonding between water molecules leads to many
interesting consequences at the visible, microscopic level.
Hydrogen bonds also give liquid water a high surface tension.
Citations:
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http://www.sciencebuddies.org/science-fairprojects/project_ideas/Chem_p021.shtml#background
http://www.education.com/science-fair/article/soapy-surfacetension/
Hypothesis
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If I add dish soap to a glass of water, then when I
put the paper ball in it will sink, because the surface
tension of soap is much denser then water.
Procedure: Materials
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Two glasses
Spoon
Water
Dish soap
Pieces of paper
Procedure: Steps
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Fill two glasses equally full with water.
In one of the cups, add about 1 oz (30 mL) of dish
soap and gently stir the solution.
Create two identical balls of paper that can fit into
your glasses of water.
Gently drop one paper ball into the plain water
and drop the other paper ball into the glass with
the soapy water solution.
You will quickly observe that the paper balls react
differently to the two fluids.
Observations Pictures
Variables
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Constants: The one glass of water without dish soap.
Controlled variables: The water that has soap
added to it compared to the original glass of
water.
Independent (manipulated) variable: The glass of
water that had dish soap added to it.
Dependent (measured) variable: The glass of water
that doesn't have dish soap added to the substance
Data/Observations
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When I put some dish soap in the glass of water
and stirred it up it was interesting seeing the surface
tension change. When I got the two paper balls and
put them in at the same time, it was cool to observe
what happened. One paper ball floated while the
other one sank. When one of the pieces of paper
sank, the other one was on the top of the glass
swimming.
Conclusion
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Surface tensions can be changed by adding
compounds to different substances. You can add, for
example, soap and that will change the surface
tension of a substance. My data does support my
hypothesis because when you add soap to the
water and then put the paper balls into it, the soap
compound will sink and the one with water will
make the other paper ball float on the top.
Citations
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http://www.stevespanglerscience.com/lab/experim
ents/sink-or-swim-surface-tension
http://www.sciencebuddies.org/science-fairprojects/project_ideas/Phys_p012.shtml
http://www.education.com/sciencefair/article/soapy-surface-tension/
http://www.sciencebuddies.org/science-fairprojects/project_ideas/Chem_p021.shtml#backgro
und