Why is boric acid classified as a monobasic acid despite having three hydroxyl groups?

Why is boric acid classified as a monobasic acid despite having three hydroxyl groups?
Boric acid's monobasic classification stems from its Lewis acidity rather than proton donation. In aqueous solution, it accepts a hydroxide ion from water, releasing one proton per molecule, which limits it to one ionizable hydrogen. This structural nuance matters commercially: buyers specifying boric acid for pH control or buffering applications must account for its weak, monobasic behavior, which differs from typical triprotic acids. The C3h symmetry of the molecule also promotes intermolecular hydrogen bonding in a planar sheet, a property that influences its crystalline form, dissolution rates, and handling characteristics in industrial processes. Understanding this chemistry helps downstream users—from glass manufacturers to pharmaceutical formulators—predict reactivity and optimize usage rates.