“活度”質疑

郭漢杰

doi:10.13374/j.issn2095-9389.2017.04.004

“活度”質疑

doi: 10.13374/j.issn2095-9389.2017.04.004

郭漢杰^1,2, ,

1) 北京科技大學冶金與生態工程學院, 北京 100083
2) 高端金屬材料特種熔煉與制備北京市重點實驗室, 北京 100083

基金項目:

國家自然科學基金資助項目(51274031)

詳細信息

中圖分類號: TF02
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- 被引次數: 0
出版歷程
- 收稿日期: 2016-04-26

Activity query

GUO Han-jie^{1,2
, ,}

1) School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China
2) Beijing Key Laboratory of Special Melting and Preparation of High-end Metal Materials, Beijing 100083, China

摘要

摘要: 為研究二元系溶液中組元摩爾分數和氣相中蒸氣壓的規律,考察了48個化合物在熔點固液相變的熔化熵變,發現相變時沒有發生顯著的化合物分解.在假設二元系溶液中存在化合物分子的情況下,組元在全濃度范圍符合拉烏爾定律,不存在Lewis定義的“活度”;通過與Mg-Si、In-Sb和Fe-Mn三個二元系實測活度結果對比,證實了計算的平衡摩爾分數即為活度值,二元金屬熔體不存在所謂“活度”的觀點.推導了在二元系金屬熔體存在一個金屬間化合物條件下平衡的摩爾分數的通用公式,以及相應的A₂B或AB型金屬間化合物的一般公式.將二元系溶液劃分為大于純組元熔點的溫度、小于純組元熔點溫度但高于液相線和低于液相線的三個區間,提出了適應不同區間的廣義拉烏爾定律的關系式.
- 活度 /
- 熱力學 /
- 平衡體系 /
- 溶液
Abstract: To investigate the laws relating to the mole fraction of a component in a binary solution and its vapor pressure, the entropies of dissolution from the solid phase to the liquid phase of 48 typical compounds were assessed and the compounds were confirmed to not decompose during the phase transition processes. Under the condition where a compound also exists in a binary liquid melt, both of the components in the whole concentration range obey Raoult's law. Specifically, there is no such thing as an"activity"as defined by Lewis. The so-called "activity" is actually the balance mole fraction in the case where all components in the system are considered by comparing with the measured activity data for Mg-Si, Sb-In, and Fe-Mn binary systems. It is verified that the calculated equilibrated mole fraction represents the activity, thereby the binary metallic melts involve no activity. In addition, a general formula is deduced for the equilibrium mole fraction in the binary system in the case where the melt contains one intermetallic compound. In particular, the cases corresponding to A₂B-type or AB-type intermetallic compounds were discussed. Finally, a broad sense Raoult's law was proposed that it is applicable in all three regions in binary solution divided by different temperatures:(I) the region corresponding to temperatures above the melting point of the component,(Ⅱ) the region corresponding to temperatures lower than the melting point of the pure component but greater than the liquidus temperature, and (Ⅲ) the region corresponding to temperatures lower than the liquidus temperature.
- activity /
- thermodynamics /
- equilibrated systems /
- solution

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參考文獻(5)

[1]	Lewis G N. The free energy of chemical substances. J Am Chem Soc,1913,35(1):1
[2]	Kubaschewski O, Alcock C B. Metallurgical Thermochemistry. 5th Ed. Oxford:Pergamon Press,1979
[5]	Eldridge J M,Miller E. Thermodynamic properties of liquid magnesium-lead alloys. Trans Met Soc AIME,1967,239(4):570
[13]	Palenzona A,Cirafici S. Dynamic differential calorimetry of intermetallic compounds:(Ⅱ) heats of formation, heats and entropies of fusion of rare earths-lead (REPb3) compounds. Thermochim Acta,1973,6(5):455
[14]	Palenzona A,Cirafici S. Dynamic differential calorimetry of intermetallic compounds:(Ⅲ) heats of formation,heats and entropies of fusion of (REIn3) and (RETl3) compounds. Thermochim Acta,1974,9(4):419