What is the approximate diameter of an oil molecule?

  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
    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. rl.bhat

    rl.bhat 4,435
    Homework Helper

    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. 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. rl.bhat

    rl.bhat 4,435
    Homework Helper

    I am getting 1.635x10-9m.
  6. 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..


    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. rl.bhat

    rl.bhat 4,435
    Homework Helper

    x1 = 4.9*1 + 6.06

    x2 = 4.9*2 + 6.06

    Continue till i = 4, simplify and add all.
Know someone interested in this topic? Share this thead via email, Google+, Twitter, or Facebook

Have something to add?