Affordable Access

deepdyve-link deepdyve-link
Publisher Website

H2CO3 forms via HCO3- in water.

Authors
Type
Published Article
Journal
The Journal of Physical Chemistry B
1520-5207
Publisher
American Chemical Society
Publication Date
Volume
114
Issue
50
Pages
16854–16859
Identifiers
DOI: 10.1021/jp1099909
PMID: 21114307
Source
Medline
License
Unknown

Abstract

According to the generally accepted picture of CO(2) dissolution in water, the formation of H(2)CO(3) proceeds in a single step that involves the attack of a water oxygen on the CO(2) carbon in concert with a proton transfer to a CO(2) oxygen. In the present work, a series of ab initio molecular dynamics simulations have been carried out along with the metadynamics technique which reveals a stepwise mechanism: the reaction of a water molecule with CO(2) yields HCO(3)(-) as an intermediate and a hydronium ion, whereas the protonation of the CO(2) moiety occurs in a separate step representing a well-defined activation barrier toward the H(2)CO(3) molecule. This alternative scenario was already taken into consideration decades ago, but subsequent experiments and calculations have given preference to the concerted mechanism. Employing extended periodic models of the CO(2)-water system that mimic the bulk aqueous environment, the present simulations yield the complete free energy profile of the stepwise mechanism and provide a detailed microscopic mechanism of the elementary steps. HCO(3)(-) formation is found to be the rate-determining step of the entire CO(2) hydration process.

Statistics

Seen <100 times