Was Ben Franklin an Early NanoscientistWas Ben Franklin an Early Nanoscientist??

Excerpt from Letter of Benjamin Franklin to William Brownrigg (Nov. 7, 1773)

...At length being at Clapham, where there is, on the Common, a large Pond ... I fetched out a Cruet of Oil, and dropt a little of it on the Water. I saw it spread itself with surprising Swiftness upon the Surface ... the Oil tho' not more than a Tea Spoonful ... which spread amazingly, and extended itself gradually till it reached the Lee Side, making all that Quarter of the Pond, perhaps half an Acre, as smooth as a Looking Glass....

... the Oil tho' not more than a Tea Spoonful ...

... perhaps half an Acre

CHALLENGE: How thick was the film of Ben Franklin’s oil?

Volume = (Area)(Thickness)

V = A T

V = 1 teaspoonful

A = 0.5 acre

~ 2 cm3

~ 2,000 m2

T = V/A

20,000,000 cm2

= 2 cm3

20,000,000 cm2

= 0.0000001 cm = 1 x 10-7 cm = 1 x 10-9 mT = 1 nanometer (nm)

The Campus PondThe Campus Pond

A plastic tray will be your model A plastic tray will be your model of a pondof a pond.

You will form a thin film using one of the You will form a thin film using one of the ingredients in olive oil.ingredients in olive oil.

That ingredient is called oleic acid.That ingredient is called oleic acid.

One end of the oleic acid molecule is One end of the oleic acid molecule is attracted to water molecules.attracted to water molecules.

If you oleic acid on water, the ends of oleic acid If you oleic acid on water, the ends of oleic acid molecules that contain oxygen atoms are attracted to molecules that contain oxygen atoms are attracted to

the surface of the waterthe surface of the water

So, even in a small drop of oleic acid, billions So, even in a small drop of oleic acid, billions of small oleic acid molecules will stand up like of small oleic acid molecules will stand up like

blades of grass on the surface of waterblades of grass on the surface of water.

Now its your turn to create a thin Now its your turn to create a thin layer on the surface of water.layer on the surface of water.

• The directions for making a thin film of oleic acid are The directions for making a thin film of oleic acid are at each end of a table.at each end of a table.

• Water has been poured into the plastic tray. Water has been poured into the plastic tray. • Your group needs to make a very dilute solution of Your group needs to make a very dilute solution of

oleic acid.oleic acid.• One drop of the solution will spread out across the One drop of the solution will spread out across the

surface of the water. surface of the water. • The alcohol dissolves in the water leaving a thin film The alcohol dissolves in the water leaving a thin film

of oleic acid on the surface of the water.of oleic acid on the surface of the water.• Then you can measure the average diameter of the Then you can measure the average diameter of the

somewhat circular thin layer of oleic acid.somewhat circular thin layer of oleic acid.

Nanoscale CalculationsNanoscale Calculations

• Worksheets have been provided for the Worksheets have been provided for the activity.activity.

• One side of the worksheet includes One side of the worksheet includes hints for calculations.hints for calculations.

• Calculators have also been provided Calculators have also been provided but need to be shared by the groupsbut need to be shared by the groups.

Form lab groupsForm lab groups

• There are 7 tables in the room.There are 7 tables in the room.

• Two groups of 3 people will work at Two groups of 3 people will work at each table.each table.

You Have Created a Langmuir FilmYou Have Created a Langmuir Film

water

hydrophobic end

hydrophilic end

Lets Compare the Results of the Two Lets Compare the Results of the Two Activities.Activities.

• How are the two activities similar?How are the two activities similar?

• How are the two activities different?How are the two activities different?