There are potential limitations to these models. For one, we assumed that the pK a data are microscopic, despite the fact that most (if not all) data come from macroscopic measurements. This does not become an issue for monoprotic acids, or acids with acidity centers of distinctly different acid strengths, but can be problematic for polyacids and species with multiple thermodynamically relevant protomers. Furthermore, we made no corrections regarding the acidity centers of the iBonD data, and so any errors in transcription may appear herein. Such issues may also limit the accuracy of our evaluations against experimental data, though any such errors would make the model appear worse than it is. The models also are only trained on single tautomeric forms, and may provide poor results when provided with alternate tautomeric forms of a species.