Chloric acid, HClO3, is an oxoacid of chlorine, and the formal precursor of chlorate salts. It is a strong acid (pKa ≈ −2.7 (***note: pKa not in agreement with properties in chem box at right)) and an oxidizing agent. Properties Chloric acid is thermodynamically unstable with respect to disproportionation. Chloric acid is stable in cold aqueous solution up to a concentration of approximately 30%, and solution of up to 40% can be prepared by careful evaporation under reduced pressure. Above these concentrations, chloric acid solutions decompose to give a variety of products, for example: 8 HClO3 → 4 HClO4 + 2 H2O + 2 Cl2 + 3 O2 3 HClO3 → HClO4 + H2O + 2 ClO2 Hazards Chloric acid is a powerful oxidizing agent. Most organics and flammables will deflagrate on contact. Production It can be prepared by the reaction of sulfuric acid with barium chlorate, the insoluble barium sulfate being removed by precipitation: Ba(ClO3)2 + H2SO4 → 2 HClO3 + BaSO4 Another method is the heating of hypochlorous acid, producing chloric acid and hydrogen chloride: 3 HClO → HClO3 + 2 HCl See also Chlorate Hypochlorous acid Chlorous acid Perchloric acid Oxidizing acid Dichlorine pentoxide References Chlorates Halogen oxoacids Mineral acids Oxidizing agents Oxidizing acids Hydrogen compounds