Other acids and bases are only incompletely dissociated into ions
in solution, and exist in part as undissociated molecules.
Dissolved hydrogen fluoride, for example, exists as an equilibrium
mixture of HF molecules and hydrated H+ and F-
The equilibrium constant for this dissociation usually is written
as Ka., for acid dissociation, rather than Keq:
Hydrogen fluoride is an inorganic acid.