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

Dissociation constants of NaCl/KCl

  1. Mar 20, 2012 #1
    What are the dissociation constants of NaCl and KCl respectively? I want to determine how much of the salt dissociates in a 1 M solution. Thanks!
  2. jcsd
  3. Mar 20, 2012 #2
    We know that both salts KCl and NaCl are highly ionic, and can confirm that they are almost completely ionized in water allowing them to make very concentrated solutions. Without knowing the dissociation constants, we can still surmise this from the table of solubilities found in Wiki ...\Solubility_Table. Both NaCL and KCl are soluble to the extent of 34-35 wt/wt% at 20C which is well above 1 M... One would expect that 1M solutions would be 100% ionized of either NaCl or KCl. It is interesting to note that as the temperature is dropped to 0C the KCl saturated solution is lower concentration than the NaCl saturated solution at 0C...(though both are still well above 1 M). KCl would be expected to crystallize first if solutions are concentrated enough and cooled!
  4. Mar 21, 2012 #3


    User Avatar

    Staff: Mentor

    It is not that easy, they do create ionic pairs in concentrated solutions, which is equivalent to the salt being "not dissociated". It is especially apparent when comparing osmotic pressure measured and calculated from the salt concentration.

    But I doubt you will find a dissociation constant. For the effect to be visible you need relatively high concentrations, which means high ionic strength, which means activities differ substantially from 1 - and it is easier and safer to prepare a table of dissociation ratios, than to determine dissociation constant.
  5. Apr 8, 2012 #4
    Hello clarinets,

    I would recommend to checkout the website (dissociationconstant.com), hopefully it would be helpful to you.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook