  The dissociation micro-states (DMS) of an $N$-protic acid are described using
set theory notation. This facilitates the mathematical description of the
dissociation micro-equilibrium (DME). In particular, the DME constants are
easily obtained in terms of the dissociation equilibrium constants and the
molar fractions of the DMSs. Representing of the DMEs in terms of graph theory
allows to identify permutations between DMSs that preserve the vertex-edge
connectivity of the graph. These permutations, along with their composition,
allow us to identify the direct product of the cyclic group $C_2$, and the
symmetric group $S_N$, $C_2\times S_N$, as the graph automorphism group of the
micro-dissociation of $N$-protic acids.
