Ionic concentration / number of ions

  1. somasimple

    somasimple 716
    Gold Member

    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. Borek

    Staff: Mentor

    What is mole definition?
     
  4. somasimple

    somasimple 716
    Gold Member

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

    Consider I'm stupid.
     
  5. Borek

    Staff: Mentor

    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. somasimple

    somasimple 716
    Gold Member

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

    (15/1000)*6.02x10E23
     
  7. Borek

    Staff: Mentor

    Wasn't that hard :wink:
     
  8. somasimple

    somasimple 716
    Gold Member

    Sure but I'm so lazy...
     
  9. somasimple

    somasimple 716
    Gold Member

  10. Borek

    Staff: Mentor

    M usually stands for mol/liter.
     
  11. somasimple

    somasimple 716
    Gold Member

    Many salt are solvated in water.
    How many water molecules are in a liter?
     
  12. somasimple

    somasimple 716
    Gold Member

    No matter, I found the response:

     
    Last edited: May 20, 2009
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