HCl, KCl and KOH solvation resolved solute-solvent interactions and solution surface stress

Abstract

An incorporation of the hydrogen bond (O:HO or HB) cooperativity notion, contact angle detection, and the differential phonon spectrometrics (DPS) has enabled us to gain refined information on the HCl, KCl and KOH solvation resolved solute-solvent molecular interactions and the solution surface stresses. Results show that ionic polarization stiffens the solvent HO bond phonon from 3200 to 3480 cm−1 in the hydration shells. The HO− in alkaline solution, however, shares not only the same HO phonon redshift of compressed water from 3200 to < 3100 cm−1 but also the dangling bonds of H2O surface featured at 3610 cm−1. Salt and alkaline solvation enhances the solution surface stress by K+ and Cl− ionic polarization. The excessive H+ proton in acid solution forms a H↔H anti-HB that depresses the solution surface stress, instead. The solute capability of transforming the fraction of the O:HO bonds of the solvent matrix is featured by: fH = 0 and fx ∝ 1-exp(-C/C0) (x = HO−, K+ and Cl−) towards saturation. Exercises not only confirm the presence of the H↔H anti-HB point fragilization, the O:⇔:O super-HB point compression, and ionic polarization dominating the performance of the respective HCl, KOH, and KCl solutions, but also demonstrate the power of the DPS that enables high resolution of solute-solute-solvent interactions and correlation between HB relaxation and solution surface stress.