if you have a reaction with an acid dissociation, where one HA goes to H + A how can the entropy be negative? I thought that one mole going to two moles would have positive entropy because of the greater disorder.

Answer 1

Think about the possibility of hydration of both + and - ions and ion-dipole type "clusters" forming so those "two" particles really aren't two particles.

Answer 2

hydration just means H2O would attach to the ions, right? would the H2O attach to the -F to form larger molecules? how does the entropy change from that?

Answer 3

responded above.