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Homework Help: Molar concentration

  1. Apr 29, 2010 #1
    Suppose i have a spherical volume of 100nm with a solution 30mM.
    How many solute molecules it corresponds to?

    My answer is about 6400...is that correct?
    im just not sure i did some conversion correctly...

    Thanks
    Alfio
     
  2. jcsd
  3. Apr 29, 2010 #2

    Borek

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    Staff: Mentor

    100nm is what? Radius? Diameter?

    6400 of what?

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  4. Apr 29, 2010 #3
    Sorry for not being clear, 100nm is the radius.
    N = 6400 is the number of solute particles I get
    from the formula c = N/(N_A*V), just wanted to know
    if its right.
    c = 30mM

    Thanks.
    Alfio
     
  5. Apr 29, 2010 #4

    Borek

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    Staff: Mentor

    Formula is OK, but I got different number. Not necesarilly correctly.

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    methods
     
  6. May 3, 2010 #5
    I did the calculation again, i got around 75000 molecules, right?
    Well..it seems i'm playing dices...

    Best,
    Alfio
     
  7. May 3, 2010 #6

    Borek

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    Staff: Mentor

    That's what I got as well.

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