Formula NameValue of K a * Values of K a for Some Common Monoprotic Acids HSO 4 - hydrogen sulfate ion1.2 x 10 -2 HClO 2 chlorous acid1.2 x 10 -2 HC 2 H 2 ClO 2 monochloracetic acid1.35 x 10 -3 HF hydrofluoric acid7.2 x 10 -4 HNO 2 nitrous acid4.0 x 10 -4 HC 2 H 3 O 2 acetic acid1.8 x 10 -5 HOCl hypochlorous acid3.5 x 10 -8 HCN hydrocyanic acid6.2 x 10 -10 NH 4 + ammonium ion5.6 x 10 -10 HOC 6 H 5 phenol1.6 x 10 -10 * The units of K a are mol/L but are customarily omitted.
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