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Here is the word problem:
In water conservation, chemists spread a thin film of an inert material over
the surface of water to cut down the rate of evaporation of water in reservoirs.
This technique was pioneered by Benjamin Franklin three centuries ago. Franklin
found that 0.10 mL of oil could spread over 40 m2 of water surface. Assuming
that the oil forms a monolayer, that is, a layer that is only one molecule thick,
estimate the length of each oil molecule in nanometers (nm).
I know that;
Volume (oil)= L^{3} = 0.1mL = 0.0000001m^{3}
Surface Area (S.A.)= L^{2}= 40m^{2}
Length (L)= 6.32455532
I'm stuck. I don't know where to begin now that I've collected my information. How can I find the length of each individual molecule in nm?
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According to the problem the thickness of the oil surface will be equal to the diameter of the oil molecule since the layer is mono layer. Also I have assumed that the molecule has a spherical shape and by length the question means its size or in other words its diameter.
Using thickness = volume / surface area you can calculate the size. 
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Last edited by sengupta (2010-08-03 10:45:48)
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