Out of blind submissions of the SAMPL7 log P challenge, there were 10 in the physical (MM) category, 10 in the physical (QM) category, and 12 in the empirical category An additional null and reference method were included in the empirical method Titration method Probabilit y pH Figure . Using the microstate probability to convert microscopic pK a predictions to macroscopic pK a 's with the titration method pK a 's. Blue and orange lines represent two states. Blue states have one more proton than the orange states, and thus a formal charge higher by +1.