Acidity and Phase Behavior of Frozen Hydrochloric Acid during Thawing
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216224%3A14310%2F24%3A00137407" target="_blank" >RIV/00216224:14310/24:00137407 - isvavai.cz</a>
Result on the web
<a href="https://pubs.acs.org/doi/10.1021/acs.jpcc.4c04540" target="_blank" >https://pubs.acs.org/doi/10.1021/acs.jpcc.4c04540</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1021/acs.jpcc.4c04540" target="_blank" >10.1021/acs.jpcc.4c04540</a>
Alternative languages
Result language
angličtina
Original language name
Acidity and Phase Behavior of Frozen Hydrochloric Acid during Thawing
Original language description
Freezing and its application is growing in popularity, yet the understanding of the nonequilibrium transformations and acidity changes that occur in frozen solutions upon thawing have remained relatively unexplored. By contrast to other acids such as nitric acid and sulfuric acid, not even the phase diagram is known fully for hydrochloric acid. Even more importantly, the nonequilibrium transformations upon heating glassy freeze-concentrated solution (FCS) are also not well understood and freeze concentration lacks quantification. This work rectifies the knowledge gap by providing the freeze-concentration factors on the example of hydrochloric acid. For this purpose, we have used differential scanning calorimetry to reveal phase changes upon heating. UV-vis spectroscopy of acid-base indicators is employed to elucidate acidity changes. All the samples reach negative values of the Hammett acidity function from -2.5 to -0.25 after freezing, showing that aqueous HCl can freeze concentrate 7-250,000 times depending on its initial concentration. We observe the glass-to-liquid transition of the freeze-concentrated glassy solution above -140 degrees C and cold crystallization of the ultraviscous FCS to HCl hydrates above -110 degrees C. Cold crystallization leads to basification, whereas acidification accompanies the subsequent melting of the eutectic ice/HCl-hexahydrate. Finally, melting of the ice immersed in solution shows basification caused by the dilution with meltwater. High (1 M) and low (<10 mM) concentrations freeze homogeneously, whereas intermediate concentrations reveal the presence of freeze-concentrated regions of higher and lower concentrations having distinct glass transition and melting temperatures.
Czech name
—
Czech description
—
Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
—
OECD FORD branch
10403 - Physical chemistry
Result continuities
Project
—
Continuities
S - Specificky vyzkum na vysokych skolach<br>I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace
Others
Publication year
2024
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Journal of Physical Chemistry C
ISSN
1932-7447
e-ISSN
—
Volume of the periodical
128
Issue of the periodical within the volume
41
Country of publishing house
US - UNITED STATES
Number of pages
12
Pages from-to
17674-17685
UT code for WoS article
001328659400001
EID of the result in the Scopus database
2-s2.0-85206127712