Weak Acid Dissociation Constants, pKa at 25°C go back to Frequently Used Tables in CEE 350 Substance Equilibrium equation pKa Applications Acetic acid CH3COOH H++CH3COO- 4.75 Anaerobic digestion Carbonic acid H2CO3 H++HCO3- 6.35 Coagulation, Corrosion Bicarbonate HCO3- H++CO32- 10.33 Softening, pH control Hydrosulfuric acid H2S H++HS- 7.2 Aeration, Odor control Hydrogen sulfide HS- H++S2- 11.89 Corrosion Hypochlorous acid HOCl H++OCl- 7.54 Disinfection Phosphoric acid H3PO4 H++H2PO4- 2.12 Phosphate removal Dihydrogen phosphate H2PO4 H++HPO42- 7.20 Readily available nutrient to plants Hydrogen phosphate HPO42- H++PO43- 12.32   go back to Frequently Used Tables in CEE 350