Abstract
Sulfuric acid is commonly known to be a strong acid and, by all counts, should readily donate its proton to formate, which has much higher proton affinity. This conventional wisdom is challenged in this work, where temperature-dependent negative ion photoelectron spectroscopy and theoretical studies demonstrate the existence of the (HCOO-)(H2SO4) pair at an energy slightly below the conventional (HCOOH)(HSO4-) structure. Analysis of quantum-mechanical calculations indicates that a large proton affinity difference (∼36 kcal/mol), favoring proton transfer to formate, is offset by the gain in intermolecular interaction energy between HCOO- and H2SO4 through the electron delocalization and formation of two strong hydrogen bonds. However, this stabilization comes with a severe entropic penalty, requiring the two species in the precise alignment. As a result, the population of (HCOO-)(H2SO4) drops significantly at higher temperatures, rendering (HCOOH)(HSO4-) to be the dominant species. This phenomenon is consistent with the photoelectron data, which shows depletion in the spectra assigned to (HCOO-)(H2SO4), and has also been verified by ab initio molecular dynamics (AIMD) simulations.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
