CO2 System Hydration and Dehydration Kinetics and the Equilibrium CO2/H2CO3 Ratio in Aqueous NaCl Solution

Alan L. Soli, Robert H. Byrne

Research output: Contribution to journalArticlepeer-review

Abstract

Observations of pH on a millisecond time scale were used to obtain the CO 2 hydration rate, the H 2 CO 3 dehydration rate, the ionization constant of H 2 CO 3 , and the equilibrium ratio of CO 2 and H 2 CO 3 concentrations over a range of temperature (15–32.5 °C). In 0.65 molal NaCl, close to the ionic strength of seawater, the H 2 CO 3 dehydration rate constant ( k D ) is well represented by the equationlnkD(s−1)=30.15−(8018)T−1,">lnkD(s−1)=30.15−(8018)T−1, and the ionization constant, K a , for H 2 CO 3 followed the relationshiplogKa=−0.994−(610.5)T−1,">logKa=−0.994−(610.5)T−1, where T is the temperature (Kelvin scale). The equilibrium ratio ( K D ) of CO 2 and H 2 CO 3 concentrations at 25 °C was equal to 848. K D ranged from approximately 840 at 15 °C to 878 at 32.5 °C. Values of K D and k D were used to calculate the CO 2 hydration rate constant, k H . Over the temperature range of this work, k H was well represented by the equationlnkH(s−1)=22.66−(7799)T−1.">lnkH(s−1)=22.66−(7799)T−1.

Original languageAmerican English
JournalMarine Chemistry
Volume78
DOIs
StatePublished - Jan 1 2002

Keywords

  • Carbonic acid
  • Hydration
  • Dehydration
  • Carbon dioxide system
  • Kinetics

Disciplines

  • Life Sciences

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