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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: zeit on September 09, 2014, 09:15:32 PM

Title: Why do some chemicals dissociate in water more than others, and..
Post by: zeit on September 09, 2014, 09:15:32 PM
Why do some chemicals dissociate in water more than others, and is the topic outside the scope of a basic chem class (101)?

I found something on wiki about an "Acid dissociation constant". Is it that complicated- can someone describe in simple terms why certain chemicals break apart more in water, signifying either acidity are being base, than others? Thanks!
Title: Re: Why do some chemicals dissociate in water more than others, and..
Post by: Borek on September 10, 2014, 02:40:27 AM
If I understand your question correctly, you will need to wait till you learn about chemical equilibrium. Basically, reactions almost never go to completion, rather, they reach an equilibrium, in which both reactants and products are present. Sometimes reaction is shifted so far to the products side we can assume it went to completion, but it is never exactly true.

Dissociation is just a reaction, sometimes it goes to completion, sometimes it doesn't. Why? It depends on many factors, but the driving force is usually the stability of the non-dissociated substance and dissociated ions - when the undissociated substance is more stable, it will prefer to stay undissociated, when the dissociations products are more stable, substance will tend to dissociate.