کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5412526 | 1393432 | 2011 | 9 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
The homogeneous nucleation in supercooled water. An examination using statistics and irreversible thermodynamics
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
According to the rate constant of crystallization, the lifetime of a droplet of supercooled liquid is Ï = 15 s at 237 K. The rate constant J strongly depends on the temperature T. The experimental results can be reproduced by the phenomenological Arrhenius equation. The plot lnJ vs. 1/T shows an ascending straight line. The slope gives the activation energy Ea = â 2.65 · 10â 18 J at 237 K. In contrast to chemical kinetics, the activation energy is negative, Ea < 0. It must be given off to the surroundings, otherwise neither nucleation nor crystallization of a droplet of supercooled water is possible. Hence the critical germ is nothing else than the transition state of crystallization of a water droplet, and the activation energy equals the enthalpy of nucleation Ea = ÎHN < 0. In combination with the enthalpy of crystallization ÎHl = â 7.4 · 10â 21 J of one H2O molecule at 237 K the number N = 3.6 · 102 of molecules can be determined, which are engaged in the formation of the critical germ and the transition state, respectively.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Liquids - Volume 164, Issue 3, 1 December 2011, Pages 178-186
Journal: Journal of Molecular Liquids - Volume 164, Issue 3, 1 December 2011, Pages 178-186
نویسندگان
Helmut Baumgärtel, Herbert W. Zimmermann,