Chemistry
Clare McGrath
December 17, 2009
Pat McClelland
The Surface Tension of Water
Procedure (part A):
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Wear your goggles and lab apron during this lab.
Obtain a penny from your teacher.
Obtain approximately 50 mL of Deionized water from the lab source.
Place the penny on a clean dry section of the lab bench
Fill the pipette with Deionized water
Hold the pipette vertically over the penny and carefully place drops of water onto the penny. Do
not touch the penny or the water with the pipette.
Count the number of drops you can add onto the penny before the water flows off the penny.
The water will tend to bulge above the penny until the surface tension is exceeded and the
water pours off the penny. Record all the total number of drops added before the water floes
off the penny.
Repeat steps 4-7 at least two more times, or until you get three consistent results.
Part B:
Independent variable: The independent variable in this experiment is the chemicals.
Dependent variable:
The dependent variable in this experiment is the surface tension with
the drops.
Control: The control of this experiment is the amount of chemicals.
Purpose: The purpose of this experiment was to find what chemical affects the surface tension.
Procedure (part B):
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Gather materials
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Fill pipette with chemical number one
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Start dropping the chemical solution vertically out of the pipette onto the penny(keep count)
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Stop adding drops of the solution onto the penny when the solution leaks off of the penny
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Record data
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Grab a new penny and repeat steps 2-4 with chemical number two
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Grab a new penny and repeat steps 2-4 with chemical number three
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Determine which chemical affects surface tension the greatest
Part C:
Independent variable: The independent variable in this experiment is the amount of chemicals.
Dependent variable:
The dependent variable in this experiment is the surface tension with
The drops.
Control: The control of this experiment is the kind of chemicals used.
Purpose: The purpose of this experiment was to find which amount of chemical affects the
surface tension the greatest.
Procedure (part C)
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Gather materials
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Determine the amount of chemical solution to use
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Fill pipette with 2 mL of chemical solution
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Start dropping the chemical solution vertically out of the pipette onto the penny(keep count)
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Stop adding drops of the solution onto the penny when the solution leaks off of the penny
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Record data
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Grab a new penny and repeat steps 3-6 with 3 mL of chemical solution
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Grab a new penny and repeat steps 3-6 with 5 mL of chemical solution
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Determine what amount of the chemical solution affects the surface tension the greatest.
Materials:
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Beakers-100 mL (1)
Disposable pipettes (4)
Disposable weighing trays (5)
Deionized water
Graduated cylinder-10 mL
Paper towels
Penny-clean, dry
Chemicals
o Sodium carbonate (Na2CO3) solution-10 mL
o Sodium Chloride (NACL) solution-10 mL
o Sodium lauryl sulfate (SLS) solution-10 mL
Observations:
Drops of
Water
Trial 1
Trial 2
Trial 3
Average
34
41
36
37
Drops of
Sodium
Carbonate
33
29
37
33
Drops of
Sodium
Chloride
19
21
21
20.3
Drops
of (SLS)
Drops of Sodium
Chloride
6
13
10
9.67
35
33
35
34.3
Conclusion
(Part B):
In this lab that my partner and I conducted, we were determining chemical affects the
surface tension.
(Part C):
In this lab that my partner and I conducted, we were trying to determine what mount of
chemical affects the surface tension the greatest.