Disassociation of ionic compound in a solution

[NOM4DCAL]

I am trying to understand what kind of experiments have been preformed which have led us to the conclusion that ionic compounds like NaCl in something like water disassociate. From my understanding of the term disassociate this means to no longer be together or to be separate. So I wonder if this was the case how are saltwater purifiers working how is it that salt water purifiers do not sometimes pull more Na+ then Cl-. Maybe we are being taught using incorrect verbiage. Like not that they are completely dissociating but instead like we already teach ionic bonds are not particularly strong bonds and thus are easily persuaded to form other compounds which have stronger bonds. I am asking because I cannot seem to get a straight answer from any of my professors on the subject. A thought experiment I often ask them when they are adamant that they truly are dissociated is if we took 100mL’s of a solution of aqueous NaCl ( about 10% salt by volume) then take a syringe of 10mL’s of the solution and tested how much Na+ and Cl- was in the 10ml syringe there would still be 10% NaCl in the syringe so how can we say that the compound has dissociated? Is there some magic happening that causes them to be present in the same amount every time or is there still a bond between them?

[tom915]

Hello,

You've hit upon a very insightful point about the nuances of "dissociation" and the behavior of ionic compounds in solution. It's true that the common simplified explanation can be misleading. Let's break down the concepts and address your questions.

What "Dissociation" Really Means

Not Complete Separation:
When we say NaCl "dissociates" in water, it doesn't mean the Na+ and Cl- ions become completely independent entities, never interacting.  HCTRA
Instead, it means the ionic lattice structure of solid NaCl breaks down, and the individual ions become surrounded by water molecules (a process called solvation or hydration).
These hydrated ions are still attracted to each other by electrostatic forces, but these forces are much weaker than the forces in the solid lattice.
Dynamic Equilibrium:
The process is dynamic. Ions are constantly moving, and there's a statistical probability of them encountering each other and temporarily forming ion pairs.
However, the vast majority of the time, they exist as individual hydrated ions.
Verbiage and Understanding:
You're right, the term "dissociation" can be misleading. It's more accurate to say that the ionic compound dissolves and the ions are solvated or hydrated.
The ionic bonds are indeed relatively weak compared to covalent bonds, and they are easily overcome by the strong interactions between water molecules and the ions.
Experimental Evidence for Ion Solvation

Several lines of evidence support the idea that ions are solvated and mobile in solution:

Electrical Conductivity:
Pure water is a poor conductor of electricity.
Aqueous solutions of ionic compounds are excellent conductors. This indicates the presence of mobile charged particles (ions).
The degree of conductivity is proportional to the concentration of ions.

Best Regards