Regardless of its origin, we attribute the higher ∆G * solv (AH) uncertainty in this work to a higher proportion of "challenging" solutes, especially carboxylic acids. Because the solutes in ∆G * solv (AH) are all acids, and many have solvation energies lower than -10 kcal mol -1 (see Figure ), we assign our high uncertainty value of 1.57 kcal mol -1 as the standard uncertainty of ∆G * solv (AH).