Carbon dioxide hydration and dehydration kinetics in seawater1

Rate constants for the hydration and dehydration reactions of carbon dioxide with water and with hydroxyl ion were measured in seawater by a pH‐stat method at salinities (× 10 3 ) from 3.4 to 37.06 at 25°C and from 5° to 35°C at a salinity of 33.77. Transition state theory was used to extrapolate the rate constants to infinite dilution, with the following results at 25°C: k co 2 = 0.037 ± 0.002·s −1 , k oh ‐ K w = (7.1 ± 0.7) × 10 −11 mol·dm −3 ·s −1 , k d = (7.6 ± 1.1) × 10 4 dm 3 ·mol −1 ·s −1 , and k hco 3 − = (1.8 ± 0.3) x 10 −4 ·s −1 . The corresponding values in seawater of 33.77 salinity and 25°C calculated from equations fit to the experimental data are 0.036, 13.5×10 −11 , 3.5 × 10 4 , and 1.40 × 10 −4 .