Draw the Lewis structure of boric acid, B(OH)₃.

(a) Is resonance important for its description?

(b) The proton transfer equilibrium for boric acid is given in a footnote to Table 6C.1. In that reaction does boric acid act as a Lewis acid, a Lewis base, or neither?
Justify your answer by using Lewis structures of boric acid and its conjugate base.

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TABLE 6C.1 Acidity Constants at 25 °C* Acid trichloroacetic acid, CCI,COOH benzene sulfonic acid, C,H-SO;H iodic acid, HIO, sulfurous acid, H₂SO3 chlorous acid, HClO₂ phosphoric acid, H,PO chloroacetic acid, CH₂ClCOOH lactic acid, CH,CH(OH)COOH nitrous acid, HNO₂ hydrofluoric acid, HF K₂ 3.0 X 10-¹ 2.0 × 10-¹ 1.7 X 10-¹ 1.5 X 10-² 1.0 x 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 pK₂ 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, H,COOH acetic acid, CH₂COOH carbonic acid, H₂CO3 hypochlorous acid, HClO hypobromous acid, HBrO boric acid, B(OH)3* hydrocyanic acid, HCN phenol, C,H,OH hypoiodous acid, HIO Ka 1.8 x 10-4 6.5 x 10-5 1.8 x 10-5 4.3 X 10-7 3.0 × 10-8 2.0 x 10-5 -9 7.2 x 10-10 4.9 X 10-¹ -10 1.3 × 10-10 2.3 × 10-11 pK₂ 3.75 4.19 4.75 6.37 7.53 8.69 9.14 9.31 9.89 10.64