The pH at which 50% of the drug molecules are ionized and 50% un-ionized (50% dissociated) It is calculated as the negative logarithm to the base 10 of the dissociation constant (Ka) of an acid Using the Ka can be inconvenient particularly for weak acids Weak...
In solution, acids tend to dissociate to form an H+ ion and a negative ion of the conjugate base (HA → H+ + A-) Reaction is freely reversible At equilibrium, a constant ratio is reached between dissociated (A-) and undissociated (HA) particles The dissociation...
Strong Acid An acid that completely dissociates in solution HA + H2O → H3O+ + A- Large Ka valueLow pKa An example is Hydrochloric acid (HCl): In solution, it almost entirely dissociates and exists as H+ ions and Cl- ions Weak Acid An acid that only partially...
The pH changes with temperature due to the facts that: Acid dissociation forward reactions are endothermic and increased temperature favours the dissociation of an acid into a hydrogen ion and its conjugate base pH is purely a measure of the concentration of hydrogen...
Neutrality of a solution is determined by having an equal number of moles of H+ and OH- ions It is often considered that a pH of 7 is neutral – however this is incorrect for several reasons: pH represents the concentration of H+ ions: pH of 7.0 equates to H+...
