Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Osmolarity question

  1. Sep 6, 2004 #1
    hello guys!

    i am stucked at this one. i hope you can help me out. i have to make this solution;

    41g/l NaCl
    Hepes-buffer 10mM
    Osm. 960 mOsm
    pH8.2


    i know how to prepare all the components, EXCEPT for 960mOsm. i wonder ;
    1. how do i know that i have 960mOsm?
    2. how to adjust the Osm, if the value is not correct.

    and lastly, what is so important with mOsm?

    thank you all for your time and sharing!
     
  2. jcsd
  3. Sep 6, 2004 #2

    chem_tr

    User Avatar
    Science Advisor
    Gold Member

    Hello

    I think this is also one of Biology's concerns, but let me contribute to the topic as a chemist.

    I have no knowledge about osmolarity, but osmotic pressure is a known issue, easily calculated by a variation of the known gas equation, Pi*V=n*R*T, where Pi is osmotic pressure, V is volume, n is number of moles, R is a constant and T is the temperature.

    However, we may speculate that osmolarity is the concentration of the compound undergoing osmosis, but calculation is the same though; Cosm=nosm/Vosm

    I am sure you know this; osmotic pressure is caused by a membrane. So you are probably using a membrane and causing something to diffuse the other side from the membrane. Maybe this approach helps you a bit.

    Regards,
    chem_tr
     
  4. Sep 7, 2004 #3

    Gokul43201

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Actually, osmolarity is calculated as the the product of the molarity and the number of ions in solution per formula unit of the molecule.

    Sometimes, the normality is used instead of molarity - I'm not sure which is the standard convention.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Osmolarity question
  1. Chemistry questions (Replies: 7)

  2. Question on SHE (Replies: 1)

  3. Hybridisation question (Replies: 9)

Loading...