[zygus]

In this equation:
H2O(l) + 57 kJ ↔ H+(aq) + OH-(aq)

Since it's endothermic, I thought it would proceed to the left to increase H2O when the temperature decreases. Could someone explain where I'm getting confused?

Also, since H2O is indicated to be a liquid, we wouldn't include it in the expression constant, correct? It would just be:
K = [H⁺][OH^-]

[Corribus]

Maybe this post I wrote some time ago will help you understand (ignore the first part addressed to Curiouscat):

http://www.chemicalforums.com/index.php?topic=68299.msg246224#msg246224

[zygus]

That's a fantastic answer, it makes a lot more sense now! Thank you so much!