共查询到19条相似文献,搜索用时 78 毫秒
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应用弯曲界面存在的气液平衡条件和界面热力学方法,分析讨论了物理化学教材中开尔文公式的推导方法和过程,指出了存在的一些容易产生误解的问题。明确指出:等温下小液滴饱和蒸气压相对于平面液体饱和蒸气压的增大是由弯曲液面下液体的附加压力引起的,而不是界面自由能变化所致。并提出了一些教学建议。 相似文献
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等温循环方法是物理化学教材中推导开尔文公式的一个经典方法。本文从热力学基本原理出发,明确指出其中小液滴可逆相变为气体的吉布斯自由能变化值应由吉布斯自由能判据求解,并对温度恒定、两相压强分别恒定时的判据进行了重新推导。同时,本文还提出了一种对推导开尔文公式的等温循环法的新理解方式,该方式在建立的"箱管模型"辅助下,意义明确,便于理解,更适宜教学使用。 相似文献
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考虑到气泡要在液体中稳定地存在,必须充入其他气体,据此导得液体在气泡中的饱和蒸气压与在平面液体中相同,仅随温度而变,而与气泡的曲率半径无关。因此,Kelvin公式不适用于微小气泡。 相似文献
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应用dF=δW'推导了拉普拉斯方程、开尔文方程、毛细管液柱高度计算公式、杨方程、贝林方程和大气分布定律等热力学公式,给出了这类推导的一般思路。 相似文献
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引入可控进气量和具有独立操作的增、减压缓冲瓶的调压装置,使气压调节缓慢可控,能连续调节缓冲瓶内气体压力以适应不同温度点的液体饱和蒸气压;可通过控制U形液柱缓慢移动来读取气液平衡状态下饱和气压值,较好地克服了以往实验中存在的调压操作困难、易发生空气倒灌及未知蒸气饱和的问题,取得了良好的实验效果,提高了实验数据的准确性。 相似文献
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P. A. Stabnikov I. A. Baidina S. V. Sysoev N. S. Vanina N. B. Morozova I. K. Igumenov 《Journal of Structural Chemistry》2003,44(6):1054-1061
A comprehensive study of copper(II) bis-ketoiminate including tensimetric analysis of sublimation and structure solution has been carried out. The temperature dependence of saturated vapor pressure over Cu(ki)2 crystals derived by the flow method is expressed by the equation lnP(atm)} = 25.31-13750/T, H
subl = -114.2 ± 1.3 kJ· mole-1, Ssubl =210.2 ± 3.0> J· mole-1 · K-1. Crystal data for CuO2N2C10H16: a=15.143(3), b=16.681(8), c=13.795(32) , space group Ccca, Z=12, d
calc = 1.47 g/cm3, R=0.029. The structure is molecular and consists of crystallographically independent Cu(ki)2 complexes of two types, one with a cis structure and the other with a cis–trans disordering. The copper atom has a plane square environment of two oxygen and two nitrogen atoms. In the cis isomer, Cu–O 1.938 and Cu–N 1.895 ; in the disordered complex, all four Cu–O(N) distances are 1.901 . 相似文献
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1-丁基-3-甲基咪唑四氟硼酸盐的热稳定性、平衡蒸汽压和标准蒸发焓 总被引:1,自引:0,他引:1
利用非等温、等温热重分析(TG)法,研究了高纯氮气气氛下1-丁基-3-甲基咪唑四氟硼酸盐([bmim][BF4])离子液体的热稳定性、平衡蒸汽压和标准蒸发焓.非等温热重(TG)曲线表明[bmim][BF4]的初始分解温度(Tonset)和最大分解速率对应的温度(Tm)分别为697和734K.然而长期等温TGA研究表明,[bmim][BF4]的最高可使用温度约为513K.另外,利用基于TG的蒸发技术研究了[bmim][BF4]的平衡蒸汽压(pe)与温度的关系并计算了标准蒸发焓.在503-543K温度范围内,离子液体[bmim][BF4]的pe和温度的关系是:lgpe=(16±1)+(-6.85±0.25)×103/T.[bmim][BF4]的标准蒸发焓为(131±5)kJ·mol-1. 相似文献
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通过简单的实验方法, 证实稀溶液蒸气压降低的现象。并从微观角度, 对此现象加以解释。理论解释与实验现象结合, 能使学生对溶液的相关性质有更加深入的理解。 相似文献
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Enthalpies of Dehydrations of Oxalate,Sulfate and Chloride Hydrates by Transpiration Method and DSC 总被引:2,自引:0,他引:2
Transpiration method was used to measure the equilibrium water vapor pressures of the dehydration of the respective hydrates,
such as oxalates, sulfates,chlorides and acetate, and the enthalpies of dehydrations (ΔH
Tr
0) of these hydrates were obtained. The heats of dehydrations (ΔH
DSC
0) were also determined by TG-DSC method. From the comparison with ΔH
Tr
0 of ΔH
DSC
0, the relation of ΔH
DSC
0/ΔH
Tr
0=R (=dehydration molar number determined by TG-DSC peak/stoichiometric dehydration molar number) was yielded. From these results,
the following relations were found: ΔH
DSC
0(corrected)=ΔH
DSC
0/R=ΔH
Tr
0
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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The calculation of the vapour pressure of organic molecules at 298.15 K is presented using a commonly applicable computer algorithm based on the group-additivity method. The basic principle of this method rests on the complete breakdown of the molecules into their constituting atoms, further characterized by their immediate neighbour atoms. The group contributions are calculated by means of a fast Gauss–Seidel fitting algorithm using the experimental data of 2036 molecules from literature. A ten-fold cross-validation procedure has been carried out to test the applicability of this method, which confirmed excellent quality for the prediction of the vapour pressure, expressed in log(pa), with a cross-validated correlation coefficient Q2 of 0.9938 and a standard deviation σ of 0.26. Based on these data, the molecules’ standard Gibbs free energy ΔG°vap has been calculated. Furthermore, using their enthalpies of vaporization, predicted by an analogous group-additivity approach published earlier, the standard entropy of vaporization ΔS°vap has been determined and compared with experimental data of 1129 molecules, exhibiting excellent conformance with a correlation coefficient R2 of 0.9598, a standard error σ of 8.14 J/mol/K and a medium absolute deviation of 4.68%. 相似文献