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What is the approximate diameter of an oil molecule?

  1. Jun 4, 2010 #1
    You can obtain a rough estimate of the size of a molecule with the following simple experiment: Let a droplet of oil spread out on a fairly large but smooth water surface. The resulting ”oil slick” that forms on the surface of the water will be approximately one molecule
    thick.
    Given an oil droplet with a mass of 8.85 × 10^−7 kg and a density of 923 kg/m3 that spreads out to form a circle with a radius of 43.2 cm on the water surface, what is the approximate diameter of an oil molecule?
    Answer in units of m.
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Jun 4, 2010 #2

    rl.bhat

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    Hi xxcherry06xx, welcome to PF.

    Volume = mass / density.

    π*r^2*d = mass/density, where d is the diameter of the molecule.

    Substitute the values and find d.
     
  4. Jun 4, 2010 #3
    I tried that but I still can't get the right answer. I keep getting 0.000000002 but it's saying it's not right on my homework.
     
  5. Jun 4, 2010 #4

    rl.bhat

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    I am getting 1.635x10-9m.
     
  6. Jun 4, 2010 #5
    Okay I will try it thank you!! I have one more question for you... it is a picture because i don't know how to type it html style but the link is..

    http://yfrog.com/jv42157278p

    I assumed it was the sum of xi = 4.9 i + 6.06 where i =1 then take that answer and ^4.
    I don't know what else that equation can mean? Can you please help.?
     
  7. Jun 4, 2010 #6

    rl.bhat

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    x1 = 4.9*1 + 6.06

    x2 = 4.9*2 + 6.06

    Continue till i = 4, simplify and add all.
     
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