<Dd> HA 2 − (aq) + H O ⇌ H O + (aq) + A3 − (aq) K </Dd> <P> An inorganic example of a triprotic acid is orthophosphoric acid (H PO), usually just called phosphoric acid . All three protons can be successively lost to yield H PO − 4, then HPO 2 − 4, and finally PO 3 − 4, the orthophosphate ion, usually just called phosphate . Even though the positions of the three protons on the original phosphoric acid molecule are equivalent, the successive K values differ since it is energetically less favorable to lose a proton if the conjugate base is more negatively charged . An organic example of a triprotic acid is citric acid, which can successively lose three protons to finally form the citrate ion . </P> <P> Although the subsequent loss of each hydrogen ion is less favorable, all of the conjugate bases are present in solution . The fractional concentration, α (alpha), for each species can be calculated . For example, a generic diprotic acid will generate 3 species in solution: H A, HA, and A . The fractional concentrations can be calculated as below when given either the pH (which can be converted to the (H)) or the concentrations of the acid with all its conjugate bases: </P> <Dl> <Dd> α H 2 A = (H +) 2 (H +) 2 + (H +) K 1 + K 1 K 2 = (H 2 A) (H 2 A) + (HA −) + (A 2 −) α HA − = (H +) K 1 (H +) 2 + (H +) K 1 + K 1 K 2 = (HA −) (H 2 A) + (HA −) + (A 2 −) α A 2 − = K 1 K 2 (H +) 2 + (H +) K 1 + K 1 K 2 = (A 2 −) (H 2 A) + (HA −) + (A 2 −) (\ displaystyle (\ begin (aligned) \ alpha _ (\ ce (H2A)) & = (\ frac (\ ce ((H+) ^ (2))) ((\ ce ((H+) ^ (2))) + ((\ ce (H+))) K_ (1) + K_ (1) K_ (2))) = (\ frac (\ ce ((H2A))) (\ ce (((H2A)) + ((HA ^ (-))) + ((A ^ (2 -)))))) \ \ \ alpha _ (\ ce (HA ^ (-))) & = (\ frac (((\ ce (H+))) K_ (1)) ((\ ce ((H+) ^ (2))) + ((\ ce (H+))) K_ (1) + K_ (1) K_ (2))) = (\ frac (\ ce ((HA ^ (-)))) (\ ce (((H2A)) + ((HA ^ (-))) + ((A ^ (2 -)))))) \ \ \ alpha _ (\ ce (A ^ (2 -))) & = (\ frac (K_ (1) K_ (2)) ((\ ce ((H+) ^ (2))) + ((\ ce (H+))) K_ (1) + K_ (1) K_ (2))) = (\ frac (\ ce ((A ^ (2 -)))) (\ ce (((H2A)) + ((HA ^ (-))) + ((A ^ (2 -)))))) \ end (aligned))) </Dd> </Dl>

What is the meaning of acids and bases