Dissociation constants of NaCl/KCl

[clarinets]

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!

 

[MrSid]

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!

 

[Borek]

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.

 

[MichaelN1]

Hello clarinets,

I would recommend to checkout the website (dissociationconstant.com), hopefully it would be helpful to you.

 

[LudusRex]

The dissociation constants of NaCl and KCl refer to the equilibrium constant (K) for the dissociation reaction of the salt in water. For NaCl, the dissociation constant is approximately 1.8 x 10^-11, while for KCl it is approximately 1.3 x 10^-10. This means that in a 1 M solution of NaCl, approximately 0.000000000018 moles of NaCl will dissociate into Na+ and Cl- ions, while in a 1 M solution of KCl, approximately 0.00000000013 moles of KCl will dissociate into K+ and Cl- ions. Keep in mind that these values are for ideal conditions and may vary slightly in different experimental setups. To determine the exact amount of salt that dissociates in a 1 M solution, you can use the dissociation constant in the equilibrium expression and solve for the concentration of ions. I hope this helps!