Measuring the Size of an Oil Molecule Grades_ 9-12 Subject

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Measuring the Size of an
Oil Molecule
Subject: Nanotechnology
National Science
Education Standards
• Science and Technology: Content Standard E
• Understandings About Science and Technology
• Abilities of technological design
What is Nanotechnology?
• Used in a wide variety of applications including:
1
medicine, waste disposal and remediation, energy
production and efficiency, electronics,
manufacturing and consumer goods
What is Nanotechnology?
• A branch of engineering on molecular scales,
typically less than 100 nanometers.
• Can help us understand how chemicals,
water, and oil interact on a molecular scale.
Deep Horizon Oil Spill
What is a Nanoscale Object?
•   Human hair averages about one tenth of a millimeter (just
less than the thickness of a dollar bill)

So just how small is 100 nanometers in comparison?
How to Calculate Nanometers
• Step 1: Convert to meters
100 nm = 10-7 m
0.1 nm = 10-4 m
• Step 2: Subtract the exponents: 7 – 4 = 3,
therefore the difference is 10-3 m, and 10-3 =
1/1000 = a thousandth
• Therefore, a hundred nanometers is a
thousandth of the diameter of a human hair.
Time to Explore!

The accuracy of your results will depend on the care
and precision you take in performing the
experiment.
Optional Preparation
• Melt wax in the saucepan.
• When entirely melted, run hot water over the
tray and dry thoroughly.
• Carefully pour the wax into the still warm tray
and spread evenly across the bottom and
sides.
Optional Preparation, continued
• If using wooden levelers, dip one of the long
ends into the wax. Repeat for the second
piece of wood.
• Ensure the wax is evenly distributed across
the bottom and sides of the tray.
• Allow to cool overnight.
To Measure the Molecule
Prepare the tray of water.
•   Pour distilled water into the tray until it is brimming over.
•   Use the small wooden wedges underneath the tray to
ensure it is level.
•   Place the levelers in the middle of the tray, until they are
about an inch from the ends.
•   Very gently sprinkle the powder onto the water surface.
Cover the entire surface between the levelers with a very
fine coat of powder. If the powder is too thick, the oil will
To Measure the Molecule
• Prepare the oil droplet.
• Make a V-shape from the fine wire.
• Tape the two ends of the V to the card so that a
portion of the wire remains protruding from the
side of the card.
• Add the oil to the small dish or tray.
• Dip only the very tip of the wire V into the oil.
To Measure the Molecule
• Make the measurements.
•   Hold the oil droplet up to the ruler and estimate the
diameter of the oil drop. It should be exactly 0.5 mm,
as measured with the micrometer (if available).
If the droplet is bigger than 0.5 mm it will spread too
wide when added to the water. If it is too big, make it
smaller by using a second piece of wire to pull away
small amounts of oil. If the droplet is smaller than 0.5
mm, record the diameter.
To Measure the Molecule
• Make the measurements, continued.
• When the droplet size is 0.5 mm or less, gently
touch the end of the wire V to the water. The
droplet will spread out in the water.
• Then measure the maximum diameter (D) of the
oil spread out on the water.
Calculate the Size of the Oil Molecule
• Calculate the volume of the oil drop:
Assume that the drop is spherical in
shape.
4 3
• The volume of a sphere is: V = p r
3
Calculate the Size of the Oil Molecule
• Calculate the area of the spread oil drop: To
calculate the area of the oil spread out on the
water assume the oil is spread out in an
approximate circle shape, so using D, the area
equals: A = p (D / 2)2
Calculate the Size of the Oil Molecule
• Calculate the thickness of the oil layer.
• Since we know the volume of the oil drop, we
can work out the oil layer thickness from the
formula for the volume of a cylinder: V = p r h
2

where height (h) equals the thickness of the
oil layer.
V
Therefore, h =
A
• The oil molecule spreads across the water
until it forms a monomolecular layer only a
molecule thick.
• The oil drop is spherical.
• The oil patch is circular.
• Unimolecular composition of the oil.
Evaluate
A molecule of motor oil is about two times the
diameter of an oleic acid molecule. If you use a
drop of motor oil the same size as the one for
olive oil, how would the size of the motor oil
patch compare?
Evaluate
Describe two possible ways to improve the
Evaluate
If the average human height is 200 cm, and the
distance from Los Angeles to New York is 4,000
km, what would be the distance from LA to NY if
the human was shrunk to 100 nanometers?

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