Compression icing of room-temperature NaX solutions (X = F, Cl, Br, I). Issue 20 (9th May 2016)

• Record Type: Journal Article
• Authors: Zeng, Qingxin; Yan, Tingting; Wang, Kai; Gong, Yinyan; Zhou, Yong; Huang, Yongli; Sun, Chang Q.; Zou, Bo
• Is Part Of: Physical chemistry chemical physics. Volume 18:Issue 20(2016)
• Page Start: 14046
• Page End: 14054
• Publication Date: 2016-05-09
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c6cp00648e
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : From the image, it is observed that salt hydration increases the critical pressures for the liquid–VI–VII phase transitions in the Hofmeister series order in terms of electronegativity difference Δ η and anion radius R . Abstract : In situ Raman spectroscopy revealed that transiting H2 O/NaX (∼64) solutions into an ice VI phase and then into an ice VII phase at a temperature of 298 K requires excessive pressures with respect to pure water. The increase of the critical pressures varies with the solute type in the Hofmeister series order: X = I > Br > Cl > F ∼ 0. The results suggest that the solute hydration creates electric fields that lengthen and soften the O:H nonbond and meanwhile shorten and stiffen the H–O bond through O–O Coulomb repulsion. Compression, however, does the opposite to solute electrification upon the O:H–O bond relaxation. Therefore, compression of the aqueous solutions recovers the electrification-deformed O:H–O bond first and then proceeds to the phase transitions, which requires excessive energy for the same sequence of phase transitions. Ice exclusion of solute disperses the frequencies of characteristic phonons and the critical pressures with unlikely new bond formation.