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Ionic concentration / number of ions

  1. Jul 31, 2008 #1

    somasimple

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    Hi all,

    We use often concentrations in chemical/biological experiments.
    It is expressed usually in mili/µ mole/cm3 or mm3

    Is there a way to know the number of ions contained in a volume?
    Is there a way to know the number of ions (or density) on a surface knowing the concentration?

    Sorry for these basic questions.
     
  2. jcsd
  3. Jul 31, 2008 #2

    Borek

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    What is mole definition?
     
  4. Jul 31, 2008 #3

    somasimple

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    Mole: a chemical mass unit, defined to be 6.022 x 10E23 molecules, atoms, or some other unit.

    Consider I'm stupid.
     
  5. Jul 31, 2008 #4

    Borek

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    Not a mass unit, quantity unit. But you are right - 6.02x1023 of elements. Just an overgrown dozen it is.

    Do you know how to calculate number of moles of substance given volume of sample and concentration?
     
  6. Jul 31, 2008 #5

    somasimple

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    I suppose.
    If the concentration is 15 mMole then the number of molecules contained per unit of volume is:

    (15/1000)*6.02x10E23
     
  7. Jul 31, 2008 #6

    Borek

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    Wasn't that hard :wink:
     
  8. Jul 31, 2008 #7

    somasimple

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    Sure but I'm so lazy...
     
  9. Jul 31, 2008 #8

    somasimple

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  10. Jul 31, 2008 #9

    Borek

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    M usually stands for mol/liter.
     
  11. May 20, 2009 #10

    somasimple

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    Many salt are solvated in water.
    How many water molecules are in a liter?
     
  12. May 20, 2009 #11

    somasimple

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    No matter, I found the response:

     
    Last edited: May 20, 2009
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