PH is dissolved in water, the pH will be greater than 7. A solution of a strong acid, such as hydrochloric acid, at concentration 1 mol dm has a pH of 0. A solution of a strong alkali, such as sodium hydroxide, at concentration 1 mol dm, has a pH of 14. Thus, measured pH values will lie mostly in the range 0 to 14, though negative pH values and values above 14 are entirely possible. Since pH is a logarithmic scale, a difference of one pH unit is equivalent to a tenfold difference in hydrogen ion concentration. <br> The pH
Acid dissociation constant the added complication that the neutral molecule is subject to an internal acid–base equilibrium in which the basic amino group attracts and binds the proton from the acidic carboxyl group, forming a zwitterion. At pH less than about 5 both the carboxylate group and the amino group are protonated. As pH increases the acid dissociates according to At high pH a second dissociation may take place. Thus the zwitterion, , is amphoteric because it may either be protonated or deprotonated. The equilibrium constant "K" for a base is usually defined as the "association" constant for protonation of the base, B,