Why percentage ionisation increases with decreasing acid concentration?

[cameron_15]

I've gone through the mathematical proof, but that won't cut it!

What's happening in terms of chemistry to cause this?
 

[pooshwaltzer]

From eons ago...

The maximum amount of an acid that can ionize is a constant. For weak acids, it's quite small. Thus when there is only a small concentration, the percent ionized will be quite large. As you increase the concentration, your increasing the total amount dissolved but the amount that ionizes will not increase beyond the maximum. Because of this, the percent of the total acid that ionizes gets smaller as the concentration increases.

[cameron_15]

...why?

sorry to be a pain

[pooshwaltzer]

From Le Châtelier’s principle, there are more “particles” or reaction components on the right side of the equation than on the left. Dilution causes the reaction to shift in the direction of the larger number of particles because this counters the effect of the decreasing concentration of particles.

[cameron_15]

So, in my own words...

Addition of water decreases the concentration of the products (hydronium and chloride ions in my case) as well as the reactants (just HCl, water omitted(?)). as it effects more particles on the Right hand side, the reaction (by le Chatelier's principle) shifts to the right to oppose this change.

thus, a greater portion of HCl is ionized, yet the overall [H+] is lower due to the increased volume.

Thank you for being so patient.