ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Infrared spectra of Mg(ClO4)2 ⋅ 6H2O at 10 K indicate a complex structure containing at least 16 distinct types of water protons. At 107.9 K this structure transforms sharply to a much simpler disordered form (ΔStrans=7.754 J K−1 mol−1), and at 273.2 K it transforms more gradually to a form in which all water protons are equivalent (ΔStrans=8.25 J K−1 mol−1). There is also a phase transition at 325.36 K (ΔStrans=21.9 J K−1 mol−1). Infrared spectra of Zn(ClO4)2 ⋅ 6H2O at 10 K indicate a disordered structure, with a continuum of proton environments, probably related to the structure of the Mg compound above 107.9 K. The phase transitions in the Zn compound at 70.1, 209.8, 290.5, and 349.0 K (ΔStrans=3.70, 0.08, 9.50, and 21.6 J K−1 mol−1, respectively) occur without a major change in the infrared spectrum. The measured entropy changes in the Mg, Zn, and Cd compounds appear to be related to the number of distinguishable types of water protons that already exist at 10 K.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.450234
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