Write the chemical formula for the conjugate base of formic acid, HCOOH and calculate its pK_b from the pK_a of formic acid (see Table 6C.1).

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TABLE 6C.1 Acidity Constants at 25 °C* K₂ 3.0 X 10-1 2.0 X 10-1 1.7 X 10-1 1.5 X 1.0 X 10-2 Acid trichloroacetic acid, CCI,COOH benzene sulfonic acid, C6H5SO3H iodic acid, HIO3 sulfurous acid, H₂SO3 chlorous acid, HClO₂ phosphoric acid, H3PO4 chloroacetic acid, CH₂CICOOH lactic acid, CH3CH(OH)COOH nitrous acid, HNO₂ hydrofluoric acid, HF 10 2 7.6 X 10-3 1.4 X 10-3 8.4 X 10 4 4.3 X 10-4 3.5 x 10-4 pKa 0.52 0.70 0.77 1.81 2.00 2.12 2.85 3.08 3.37 3.45 Acid formic acid, HCOOH benzoic acid, C,H₂COOH acetic acid, CH,COOH carbonic acid, H₂CO3 hypochlorous acid, HCIO hypobromous acid, HBrO boric acid, B(OH)3¹ hydrocyanic acid, HCN phenol, C,H,OH hypoiodous acid, HIO K₂ 1.8 X 10 4 6.5 x 10-5 1.8 X 10-5 4.3 X 107 3.0 X 108 2.0 × 10-⁹ 7.2 X 10-10 4.9 X 10-10 1.3 X 10-10 2.3 X 10-11 pKa 3.75 4.19 4.75 6.37 7.53 8.69 9.14 9.31 9.89 10.64