The Final Frontier of pH and the Undiscovered Country Beyond

The comparison of volumes of cells and subcellular structures with the pH values reported for them leads to a conflict with the definition of the pH scale. The pH scale is based on the ionic product of water, Kw = [H +]6[OH2].We used Kw [in a reversed way] to calculate the number of undissociated H2O molecules required by this equilibrium constant to yield at least one of its daughter ions, H+ or OH2 at a given pH. In this way we obtained a formula that relates pH to the minimal volume VpH required to provide a physical meaning to Kw, VpH~10 DpH{pKw=2D